ORIGINAL PAPER

Systematics and Phylogeny of Paleocene-Eocene Nyctitheriidae(Mammalia, Eulipotyphla?) with Description of a new Speciesfrom the Late Paleocene of the Clarks Fork Basin, Wyoming, USA

Carly L. Manz & Jonathan I. Bloch

# Springer Science+Business Media New York 2014

Abstract Nyctitheriidae is a diverse group of small, insectiv-orous mammals from the Paleogene of Asia, North America,and Europe that have alternately been linked to Eulipotyphla(shrews, moles, hedgehogs, solenodons), Euarchonta (pri-mates, tree shrews, dermopterans), or Chiroptera (bats).Even intrafamilial relationships are poorly understood,resulting in ambiguity regarding morphological character po-larity critical for evaluating supraordinal relationships andpaleobiogeographic patterns. To help address this issue, weperformed a cladistic analysis of 51 North American,European, and Asian nyctitheriid species, including a newnyctitheriid, Plagioctenodon thewisseni sp. nov. from the latePaleocene of Wyoming, using 66 characters derived fromdental morphology. Although the oldest nyctitheriids arefound in North America, the resulting most-parsimoniouscladograms support an Asian origin of the family with dis-persal into North America by the early Paleocene. AmongNorth American and European groups, the subfamiliesNyctitheriinae and Amphidozotheriinae, and the generaLeptacodon and Saturninia are not monophyletic and requirefuture study and revision. The multi-species generaNyctitherium, Plagioctenodon (including P. thewisseni),Plagioctenoides, Cryptotopos, and Euronyctia are found tobe monophyletic, whereasWyonycteris is paraphyletic, havingPontifactor bestiola nested within it. The earliest knownEuropean nyctitheri ids (Leptacodon nascimentoi ,Placentidens lotus, Plagioctenodon dormaalensis,

Wyonycteris richardi) appear in the early Eocene and are eachfound in an otherwise strictly North American cladeconsisting of either solely Paleocene or a combination ofPaleocene and Eocene taxa, suggesting at least four earliestEocene dispersals between North America and Europe.

Keywords Nyctitheriidae . Leptacodon . Plagioctenodon .

Paleogene . Systematics . Biogeography

Introduction

Nyctitheriidae is an extinct family of small-bodied mammalswith sectorial teeth known from the Paleocene-Eocene ofNorth America and Asia, and the Eocene-Oligocene ofEurope. Nyctitheriids were likely insectivorous and may havehad similar ecological adaptations to those of extant shrews(Lopatin 2006; Rose et al. 2012). The fossil record ofnyctitheriids consists largely of isolated teeth and jaw frag-ments, providing limited morphological information forreconstructing phylogenetic relationships betweennyctitheriids and other mammalian clades. Consequently,nyctitheriids have been hypothesized to be closely related toa diverse array of clades, including Chiroptera, Eulipotyphla,and Euarchonta, by several authors without a clear consensusbeing reached. This diverse range of suggested relationships,along with their early Paleocene appearance in the fossilrecord and primitive dental morphology, suggests thatnyctitheriids may be important taxa for understanding earlyboreoeutherian (Euarchontoglires + Laurasiatheria) evolution.

Suprafamilial Relationships

Marsh (1872) classified the first nyctitheriid, Nyctitheriumvelox, as a chiropteran based on its dental morphology. Inthe following decades, some taxa first classified as

C. L. Manz (*)Department of Geological Sciences, University of Florida,Gainesville, FL 32611, USAe-mail: clmanz@ufl.edu

C. L. Manz : J. I. BlochFlorida Museum of Natural History, University of Florida,Gainesville, FL 32611, USA

J Mammal EvolDOI 10.1007/s10914-014-9284-3

chiropterans (i.e., Paradoxonycteris soricodon [Revilliod1922] and Wyonycteris chalix [Gingerich 1987]) were laterrecognized as nyctitheriids, further illustrating the morpholog-ical similarities between early bats and nyctitheriids. Thesesimilarities in dental morphology include: 1) a buccal cingulidon the lower molars in N. velox (Robinson 1968); 2) W-shaped ectoloph on the upper molars of Pontifactor bestiola(West 1974), W. chalix (Gingerich 1987), Wyonycterisrichardi (Smith 1995), Euronyctia (Sigé 1997), andParadoxonycteris (Hooker and Weidman 2000); 3) skewedlower molars with higher lingual cusps than labial present inmost species of Plagioctenodon (Bown and Schankler 1982;this publication), Nyctitherium krishtalkai (Christiansen andStucky 2013), Ceutholestes dolosus (Rose and Gingerich1987), P. bestiola (West 1974), Wyonycteris taxa (Gingerich1987; Smith 1995; Secord 2008; Beard and Dawson 2009),Plagioctenoides taxa (Rose et al. 2012), and Placentidenslotus (Russell et al. 1973); and 4) a simple P4 with a reductionin size and number of cusps of the talonid basin. This last traitoccurs throughout Nyctitheriidae, from the primitive Asiantaxa near the base of the family (i.e., Missiaen and Smith2005; Lopatin 2006) to more derived North American andEuropean taxa, such as Plagioctenoides (Rose et al. 2012) andAmphidozotherium (Sigé 1976). However, many of thesecharacteristics are found throughout the placental mammalradiation, suggesting that they might be easily acquiredthrough parallel or convergent evolution. Furthermore, char-acteristics likely to be synapomorphies for early bats, such as abuccal cingulid and reduced para- and metaconules on theupper molars, do not occur in most nyctitheriids (Hand et al.1994). Those nyctitheriids that do possess these chiropteransynapomorphies, such as N. velox and some late EoceneEuropean nyctitheriids, have other derived traits, such as largepostcingula and hypocones on the upper molars that are quitedifferent from early bats, indicating that they are unlikelydirectly related to that radiation.

Less controversial has been a suggested link betweenNyctitheriidae and Eulipotyphla, a group that includesmodern shrews, moles, hedgehogs, and solenodons, ei-ther with Soricomorpha (Simpson 1928; Butler 1988;McKenna and Bel l 1997) or Er inaceomorpha(McKenna 1968; Robinson 1968; Sigé 1976). Thesehypotheses are less focused on derived synapomorphies,and instead are based on observations that nyctitheriidsexhibit a dental morphology intermediate to primitiveeutherians and extant eulipotyphlans and thus makelikely candidates for the ancestral stock of Eulipotyphla(Dawson and Krishtalka 1984; Butler 1988). For example,Butler (1988: 132) notes the “advances” in nyctitheriids,including multicuspid incisors, reduction in canine size, andwidening of the upper molar postcingulum that could be thefirst steps in the highly derived dilambdodonty andzalambdodonty of some eulipotyphlans.

In contrast to these dentition-based hypotheses, athird supraordinal relationship for Nyctitheriidae wasproposed based upon the first described nyctitheriidpostcrania. Hooker (2001) observed that isolatedcalcanea and astragali attributed to the Europeannyctitheriid Cryptotopos sp. exhibit two characteristicsproposed to be euarchontan synapomorphies (e.g.,Szalay and Drawhorn 1980; Silcox et al. 2005): a distalsustentacular facet on the calcaneum and confluent ectaland navicular facets on the plantar surface of the as-tragalus. Consequently, results from a phylogenetic anal-ysis that included tarsal characters suggested thatNyctitheriidae might be stem euarchontans, the orderthat includes primates, treeshrews, and dermopterans(Hooker 2001). More recently, a calcaneum has beenattributed to a second European nyctitheriid, Plagioctenodondormaalensis (as “Leptacodon dormaalensis”), which strong-ly resembles the calcaneum of Cryptotopos sp. (Coillot et al.2013).

Intrafamilial Relationships

A major impediment to understanding the relationshipsof nyctitheriids to higher eutherian clades is ambiguityof character polarity due primarily to poorly-understoodintrafamilial relationships. Currently, the clade includesroughly 70 species classified in 20 genera, with severaltaxa under dispute over their validity or even inclusionwithin the family. In the last century, there have beenmany sub-c lades proposed wi th in the fami lyNyctitheriidae (e.g., Simpson 1928; Krishtalka 1976;Sigé 1976; Bown and Schankler 1982; McKenna andBell 1997; Lopatin 2006) but there is little consensusamong authors (for review see Robinson 1968; Sigé1976; Gunnell et al. 2008).

The most recent classification of Nyctitheriidae includesrecognition of five subfamilies (Lopatin 2006): Asionyctiinae,Praolestinae, Eosoricodontinae, Nyctitheriinae, andAmphidozotheriinae. The former three subfamilies solely in-clude Asian taxa and the latter two consist of a mixture ofEuropean and North American taxa with the exception of asingle Asian nyctitheriid included in the Nyctitheriinae.Nyctitheriinae is thought to be the most primitive nyctitheriidsubfamily and includes species in the North American generaNyctitherium, Leptacodon, and Pontifactor, the Europeangenera Saturninia, Scraeva, and Euronyctia (although thisgenus is considered an amphidozotheriine by Hooker andWeidmann [2000]), and the Asian genus Yuanqulestes(McKenna and Bell 1997; Lopatin 2006). These taxa exhibita broad range of dental morphologies and are mostly differ-entiated from the other subfamilies based on the presence of asubmolariform lower fourth premolar (P4) (Lopatin 2006).

J Mammal Evol

The Nyctitheriinae includes two speciose and prob-lematic genera: Leptacodon and Saturninia from NorthAmerica and Europe, respectively. These genera havebeen treated as wastebasket taxa for plesiomorphicnyctitheriid species from their respective continents.Although some recent efforts have been made to reviseLeptacodon and Saturninia (e.g., Sigé 1997; Hooker andWeidmann 2000; Beard and Dawson 2009), they areboth likely to be paraphyletic or even polyphyletic ascurrently defined (see Results and Discussion).

Reconstructing the primitive condition of nyctitheriidsis complicated in part because the oldest members ofthe family are poorly represented in the fossil record.The earliest definitive nyctitheriids, Leptacodon tenerand Leptacodon munusculum, appear in the TorrejonianNALMA. The oldest known proposed nyctitheriid,Leptacodon proserpinae, was recovered from just afterthe Cretaceous-Paleogene boundary in the PuercanNorth American Land Mammal Age (NALMA) ofMontana (Van Valen 1978) with only the P4 described.The classification of this taxon is somewhat question-able, though, due to the paucity of fossils attributed toit (Gunnell et al. 2008). Meanwhile, the proposedCretaceous nyctitheriid Paranyctoides has since beenargued to be more closely related to the Cretaceouseutherian family Zhelestidae (Archibald et al. 2001;Averianov and Archibald 2013).

Species classified as Leptacodon are widely consid-ered to be the most primitive nyctitheriids and aretherefore crucial to understanding the phylogenetic rela-tionship of the family to higher clades. However, sincethe description of the type species, Leptacodon tener,more than ten species have been classified in this genus,many of which have been challenged by later authorsand the monophyly of the group has been called intoquestion (Bown and Schankler 1982; Gunnell et al.2008). Species classified as Leptacodon are predomi-nantly found in North America, outside of which onlyLeptacodon nascimentoi from Portugal is still consid-ered valid. Whereas Smith (1996) suggested that“Gypsonictops dormaalensis” from Belgium was betterclassified in Leptacodon (“Leptacodon dormaalensis”),wh i c h h e c on s i d e r e d a s en i o r s y nonym o fPlagioctenodon, we follow Beard and Dawson (2009)who recognized the validity of Plagioctenodon as distinctfrom Leptacodon, with Plagioctenodon dormaalensis classi-fied in that genus.

Most of the diagnostic characters for Leptacodon areconsidered to be primitive for Nyctitheriidae and thereis little agreement on what, if any, synapomorphies existfor the genus. Matthew and Granger (1921) describedLeptacodon tener from the Tiffanian NALMA and orig-inally placed it within Leptictidae. Recognizing the

primitive morphology of L. tener, they called it “theleast specialized in molars and premolars of any mem-ber of Leptictinae” (Matthew and Granger 1921: 3). Theproposed diagnostic characters for Leptacodon includedmolars with lower trigonids than those of the leptictidProdiacodon, distinct paraconids, and a reduction inmolar size from first to third, characters that can befound in most other nyctitheriid taxa. The meaning ofanother character, the “protoconid overtopping innercusp,” is unclear, but if it refers to a taller protoconidthan metaconid, the only other species of Leptacodonwith this state is Leptacodon packi, whereas a tallerprotoconid than metaconid is frequently found in othernyctitheriids not classified as Leptacodon (See character38, state “1,” in Appendix 3).

Simpson (1935) later revised the generic diagnosis, addingcharacteristics of the P4 and the third lower molar (M3). Henoted that the P4 has a small, highly-positioned metaconidpartially joined with the protoconid and a low, yet distinctparaconid, whereas the M3 talonid exhibits three subequalcusps with a “projecting” hypoconulid and a subequal orslightly higher protoconid than metaconid (Simpson1935). McKenna (1968) described an upper dentitionassociated with the type of Leptacodon tener and arguedfor its classification in Nyctitheriidae rather thanLeptictidae. Rose et al. (2012) cited a low, crest-likeparaconid, centrally positioned hypoconulid, and ab-sence of a mesostyle as diagnostic features ofLeptacodon; however, they also pointed out that thesecharacters could be plesiomorphic. Another problemchallenging the monophyly of Leptacodon is the mor-phological similarities of Leptacodon and Plagioctenodon,causing authors to either synonymize the two (Smith 1996)or to suggest new taxonomic attributions for some of thespecies (Bown and Schankler 1982; Beard and Dawson2009).

Here, we describe a new nyctitheriid species,Plagioctenodon thewisseni, from the late Paleocene of NorthAmerica, provide the first description of parts of the anteriordentition of Plagioctenodon rosei, and perform the most ex-haustive phylogenetic analysis to date for Nyctitheriidaeusing an original character-taxon matrix spanning 51species of nyctitheriids. Although our study provides abetter understanding of intrafamilial relationships andcharacter polarities within Nyctitheriidae and compellingevidence that many of the current generic attributionsfor nyctitheriid species are in need of revision, we arelimiting the systematic focus of this paper to the com-position of a monophyletic Plagioctenodon. Naming anddiagnosing new genera is outside of the scope of thispaper. Although it is likely that some genera, particu-larly Leptacodon and Saturninia, are paraphyletic oreven polyphyletic, we will not be placing the generic

J Mammal Evol

names in quotation marks until there is a greater con-sensus on the composition of these genera withinNyctitheriidae so as to avoid confusion with the existingliterature.

Materials and Methods

Fossil Recovery

Fossils of Plagioctenodon thewisseni and Plagioctenodonrosei were recovered from a freshwater limestone nodulein the Clarkforkian (Cf) NALMA, Cf-3 faunal zone, ofthe Willwood Formation, Wyoming, USA (Fig. 1).Paleocene and Eocene freshwater limestones from theWillwood Formation preserve fossils of small vertebratesnot often represented in collections made predominantlyby surface prospecting, including rare or new species ofbirds (Houde 1986, 1987; Gingerich 1987) and mammals(Gingerich 1987; Rose and Gingerich 1987; Bloch et al.1998, 2007; Bloch and Boyer 2001). Freshwater lime-stones in the Willwood Formation are often found aslenses at discrete levels associated with drab paleosols,possibly forming in depressions on the distal floodplainwhere the water table was high or after periodic flooding(Bloch and Bowen 2001; Bowen and Bloch 2002). Thelimestone nodule containing the holotype for the newspecies P. thewisseni, UM 86725, was collected at SC-117, one of the University of Michigan Museum ofPaleontology Sand Coulee vertebrate localities. Additionalfossils recovered from limestones found at other latestClarkforkian Sand Coulee localities are also referred to

this species, including those with dentally associated craniaand postcrania. Additionally, palates and dentaries ofP. rosei have been recovered with most or all anteriorteeth preserved. All skeletal and dental elements ofP. thewisseni and P. rosei were extracted from limestoneby etching with 7 % formic acid buffered with calciumphosphate tribasic and careful documentation of associatedbones through photography, similar to the methodology ofBloch and Boyer (2001).

Imaging and Measurements

High-resolution images were generated from three-dimensional digital reconstructions using μCT data obtainedfrom either the Yale University Core Center forMusculoskeletal Disorders microCT facility using a ScancoMedical μCT 35 machine or the Shared MaterialsInstrumentation Facility (SMIF) at Duke University using aNikon XT H 225. Specimens were adhered to wax-covereddiscs or mounted in foam to prevent movement during scan-ning and were scanned at resolutions less than 2μm.Three-dimensional digital reconstructions and two-dimensional still images were created using Aviso 7 or8 (http://www.vsg3d.com/avizo). Unfortunately, accuratemeasurements could not be directly obtained from scandata from the Duke SMIF lab due to an unrecognizeddetector misalignment. Instead, all measurements wereperformed using a Gaertner Scientific Corporation mi-crometer, which was checked for accuracy using a pairof digital calipers.

Measurements for all teeth (Tables 1 and 2) are maximumlengths and widths. The lower premolar lengths were mea-sured parallel to the dentary and widths were perpendicular.

Fig. 1 Map of the Bighorn and Clarks Fork basins in north central Wyoming. All fossils of Plagioctenodon thewisseni were recovered from the SandCoulee localities in the Clarks Fork Basin located north of the Bighorn Basin

J Mammal Evol

Measurements of the lower molars were obtained bydrawing a line through the metaconid and protoconidand taking the maximum length and width that wereperpendicular and parallel to that line, respectively, be-cause of the oblique position of some nyctitheriid mo-lars with respect to the dentary. The simple P1-P2 wereoriented so that the length was taken along the longaxis of the teeth and the width was perpendicular to thatmeasurement. Measurements of P3-M3 were obtained bydrawing a line through the paracone and metacone and takingthe maximum length and width that were parallel and perpen-dicular to that line, respectively, following the “Type 1”meth-odology of Secord (2008).

Choice of Taxa Used in the Phylogenetic Analysis

The nyctitheriids in this matrix include the five currentlyproposed Plagioctenodon species, eight Leptacodon species(only excluding Leptacodon proserpinae), the fourteen re-maining North American taxa, nineteen Europeannyctitheriids, and five Asian species. The taxa were codedfrom specimens, casts, and the literature (Appendix 1).European nyctitheriid taxa that were not included are eitherfrom the later (latest Eocene to Oligocene) portion of thefamily’s lineage (Cryptotopos communis, Darbonetusaubrelongensis, Darbonetus tuberi, Euronyctia belgica,Euronyctia franconica, Euronyctia recta, Euronyctiasaturninensis, Euronyctia tobieni, Oligonyctia hoffmani,Sigényctia oligocoena) or are systematically questionable asto their inclusion in Nyctitheriidae (Clinopternodus gracilis,

Remiculus). Most of the Asian-endemic nyctitheriids havebeen proposed to form a monophyletic clade resulting froma single migration event of nyctitheriids from North Americaduring the early Tiffanian NALMA (Missiaen and Smith2005). Consequently, the inclusion of Asian nyctitheriidswas limited to well-known representatives of the three strictlyAsian subfamilies (Asionyctinae, Eosoricodontinae, andPraolestinae) proposed by Lopatin (2006) to test their mono-phyly relative to included North American and European taxa.A single Asian species, Yuanqulestes qiui, was classified inthe otherwise North American and European subfamilyNyctitheriinae, but this hypothesis could not be assessed andthe species could not be included in the matrix using theimages from the primary literature because they were linedrawings of four isolated teeth solely in occlusal view (Tong1997).

Inclusion of Leptacodon proserpinae hindered the resolu-tion of our phylogenetic results in early iterations of ouranalysis due to the limited morphological information avail-able for this taxon and the destabilizing effect on our strictconsensus tree. Leptacodon proserpinae is a rare taxon andonly a single P4 has been described and figured in the literature(Van Valen 1978). Because of this, only eight characters couldbe coded for the taxon. If L. proserpinae is a nyctitheriid, itwould be the oldest one known and would likely occupy abasal position in the family. But until more fossils ofL. proserpinae are known, it is impossible to provide a moredetailed phylogenetic hypothesis for the species in relation tothe rest of Nyctitheriidae.

Maelestes gobiensis, a Cretaceous eutherian, was used asan outgroup to approximate an early eutherian morphology inlight of the primitive dental morphology of nyctitheriids. Theteeth of Macrocranion junnei and Adunator minutus havemany morphological similarities with those of nyctitheriidsand were also included in this analysis as outgroups that moreclosely approximate the sister group to nyctitheriids thanM. gobiensis. However, M. junnei and A. minutus were nottreated as forced outgroup taxa in the analysis. Some differ-ences in character states are likely derived and their inclusionin the analysis was used to test whether the taxa with ques-tionable placement in Nyctitheriidae would fall outside thefamily. The Paleocene genus Adunator (includingDiacocherus; see Novacek et al. 1985; Secord 2008), withthe species A. minutus, A. martinezi, A. fredericki, A. lehmani,A. amplus, and A. abditus, and the Eocene genusMacrocranion, with the species M. junnei, M. germonpreae,M. nitens, M. robinsoni, M. tenerum, M. tupaiodon, andM. vandebroeki, are known from North America and Europeand are commonly placed in the eulipotyphlan suborderErinaceomorpha (Novacek et al. 1985; McKenna and Bell1997; Gunnell et al. 2008). Recent studies have questionedthis placement and instead suggested an affinity with theafrotherian macroscelideans for both genera, as well as several

Table 1 Measurements of the upper teeth of Plagioctenodon rosei

UM 39843 UM 39875 UM 76895 UM 77032 Mean

P1 l 0.84 0.84

P1 w 0.45 0.45

P2 l 0.98 0.98

P2 w 0.49 0.49

P3 l 1.17 1.17

P3 w 0.78 0.78

P4 l 1.57 1.71 1.71 1.66

P4 w 1.81 1.92 1.99 1.89 1.90

M1 l 1.67 1.74 1.73 1.59 1.68

M1 w 1.93 2.39 2.17 2.08 2.14

M2 l 1.56 1.55 1.46 1.52

M2 w 2.34 2.07 2.03 2.14

M3 l 1.27* 1.27

M3 w 1.71* 1.71

l length, w width. *Measurements may not be representative of a typicalP. roseiM3 because UM76895 contains a supernumeraryM4 (Gingerich1987), which may have affected the development and dimensions of theM3

J Mammal Evol

other taxa traditionally considered to be erinaceomorphs(Penkrot et al. 2008; Hooker and Russell 2012; Roseet al. 2013). Regardless of the proper ordinal phyloge-netic position of Macrocranion and Adunator, their geo-graphic and temporal proximity and morphological sim-ilarities to nyctitheriids suggest that they are good gen-era to test the placement of taxa within Nyctitheriidae.Adunator minutus and M. junnei were chosen to repre-sent these two genera because both taxa are well repre-sented in the fossil record and are not considered de-rived within their respective clades.

Body Mass Calculations

Estimated weight in grams was calculated for all species ofnyctitheriids included in the cladistic matrix for which eitherthe M1 or M

1 was known. Two separate equations based onthe size of M1 or M

1 (Bloch et al. 1998) were used to estimatebody mass with 95% confidence intervals. The maximumlength and maximum width of complete teeth were compiledfrom the literature for each species (Appendix 1) and thenaveraged for each tooth position. Tooth sizes of theM1 andM

1

were then calculated by multiplying the averaged maximum

Table 2 Measurements of the upper and lower teeth of Plagioctenodon thewisseni

UM 86725Left

UM86725Right

UM39873

UM83931

UM82576

UF 294696Left

UF 294696Right

UF289746Left

UF 289746Right

UF289747

Mean

P1 l 0.75 0.69 0.75 0.73

P1 w 0.31 0.30 0.40 0.33

P2 l 0.88 0.90 0.89

P2 w 0.35 0.36 0.35

P3 l 0.80 0.85 1.05 0.75 0.87 0.86

P3 w 0.38 0.38 0.45 0.38 0.33 0.38

P4 l 1.20 1.17 1.15 1.16 1.04 1.10 1.07 1.12

P4 w tri 0.59 0.52 0.52 0.50 0.44 0.49 0.55 0.51

P4 w tal 0.47 0.47 0.49 0.42 0.40 0.40 0.47 0.44

M1 l 1.23 1.32 1.29 1.30 1.22 1.22 1.26

M1 w tri 0.73 0.73 0.74 0.73 0.76 0.72 0.73

M1 w tal 0.75 0.66 0.73 0.83 0.78 0.70 0.74

M2 l 1.16 1.20 1.32 1.24 1.16 1.10 1.17 1.19

M2 w tri 0.74 0.80 0.75 0.82 0.74 0.78 0.73 0.76

M2 w tal 0.73 0.73 0.67 0.74 0.73 0.71 0.75 0.72

M3 l 1.16 1.15 1.00 1.06 1.10 1.09

M3 w tri 0.68 0.70 0.69 0.63 0.59 0.66 0.66

M3 w tal 0.57 0.57 0.52 0.56 0.57 0.56

P1 l 0.62 0.62

P1 w 0.29 0.29

P2 l 0.67 0.85 0.76 0.76

P2 w 0.32 0.38 0.37 0.35

P3 l 0.94 0.93 0.99 0.96 0.95

P3 w 0.59 0.60 0.74 0.74 0.67

P4 l 1.24 1.22 1.21 1.16 1.25 1.18 1.21

P4 w 1.43 1.48 1.39 1.41 1.36 1.36 1.40

M1 l 1.22 1.28 1.18 1.22 1.24 1.23

M1 w 1.52 1.65 1.53 1.61 1.55 1.57

M2 l 1.13 1.15 1.14 1.16 1.13 1.14

M2 w 1.57 1.56 1.58 1.56 1.54 1.56

M3 l 0.86 0.83 0.78 0.89 0.89 0.85

M3 w 1.41 1.36 1.25 1.33 1.34

l length,wwidth,w triwidth of the trigonid,w talwidth of the talonid, h height. The P1- P3 does not have a talonid, so the total width can be found in thew tri row

J Mammal Evol

length by the averaged maximum width of each tooth.Incomplete teeth with an estimated length or width wereincluded because in some species they represent the only M1

or M1 published in the literature.Some species are represented mostly by isolated teeth in

the fossil record and theM1 andM1 could not be differentiated

from the M2 or M2, respectively (e.g., Sigé 1976,1997). Only teeth that could be definitively attributedto M1 or M1 were used in the body mass equations. Forthis reason, we were unable to calculate an estimatedweight for Saturninia intermedia or Saturninia grandis.Plagioctenoides tombowni and Saturninia pirenaicacould not be included because neither has a completeM1 or M1 published in the literature.

The dimensions of the upper teeth of Plagioctenodon roseihave not been published, so measurements of the upper teethof P. rosei are provided here (Table 1) taken from specimensUM 39843 and UM 39875 and casts UM 76895 and UM77032. We were unable to include measurements from manyof the specimens recovered from the limestones because mostof them are occluded or otherwise unable to be mea-sured using a micrometer. The measurements fromTable 1 were used to calculate the estimated weight ofP. rosei based on the M1.

The dimensions for the M1 of Leptacodon nascimentoiwere taken from SV3-300 (Estravis 1996: Fig. 10), which isidentified as the “M2 (?)” in the literature (Estravis 1996). Thistooth, along with SV2-12 (identified as an M1, but we believeto be an M2) are isolated teeth. Based on the upper molarmorphology of other nyctitheriid taxa, SV3-300 appears to bean M1 because of the distinctive anteriorly projectingparastylar lobe that is positioned almost directly anterior tothe paracone. This is a feature commonly found in the M1 ofother nyctitheriids (e.g., Leptacodon packi [Secord2008] , Wyonyc t er i s cha l i x [Ginge r i ch 1987] ,Nyctitherium velox [Robinson 1968], Pontifactorbestiola [West 1974]) but not in the M2. SV2-12 insteadhas a more labially directed parastylar lobe, which isthe state of the M2 in most other nyctitheriids. SV2-12also has a more rectangular trigon basin with a greaterwidth to length ratio than SV3-300, which is anotherfeature that distinguishes the M2 from the M1 innyctitheriids (e.g., Leptacodon tener [McKenna 1968],P. rosei [Gingerich 1987], P. bestiola [West 1974]).

Phylogenetic Analysis

The phylogenetic analysis is based on a character-taxon matrixthat includes 66 dental characters coded for 51 nyctitheriids, twofossil erinaceomorphs, and the outgroup Maelestes gobiensis(Appendix 1). It should be noted that several characters in ourmatrix are similar to those recently published by Christiansenand Stucky (2013). However, wording and character states vary

between the two matrices, primarily due to differences in scopeof study and issues surrounding outgroup choice. The analysispresented here is focused on determining character polarity inearly nyctitheriids and how species classified in the generaLeptacodon and Plagioctenodon are related to other NorthAmerican taxa, contemporary European taxa, and the endemicAsian subfamilies. The character-taxon matrix of Christiansenand Stucky (2013) was more limited in scope, testing relation-ships of Nyctitherium and Acrodentis species from the late earlyEocene (Wasatchian-7) Wind River Formation in relation toother select North American nyctitheriids.

A phylogenetic analysis was performed in TNT v. 1.1(Goloboff et al. 2008) using maximum parsimony. The‘New Technology Search’ was first utilized with the‘Sectorial Search,’ ‘Ratchet,’ and ‘Tree Fusing’ options se-lected and allowing the consensus to stabilize five times.These trees were then used as the starting point in a‘Traditional Search’ that searched for additional trees usingtree bisection and reconnection (TBR) branch-swapping. Allcharacters were treated as unordered and equally weighted.Bremer values were calculated from 50,000 suboptimal treesup to ten steps longer than the most parsimonious tree usingthe Bremer script that is included in the TNT download.Retention and consistency indices were calculated using thestats available on the TNTwiki (http://tnt.insectmuseum.org).

Institutional Abbreviations

UF, Vertebrate Paleontology collection, Florida Museum ofNatural History, University of Florida, Gainesville, FL; UM,University of Michigan, Museum of Paleontology, AnnArbor, MI; YPM, Yale Peabody Museum, New Haven, CT;YPM-PU, Princeton University collections, Yale PeabodyMuseum, New Haven, CT.

Systematic Paleontology

Class Mammalia Linnaeus, 1758Order Eulipotyphla Waddell, Okada, and Hasegawa, 1999Family Nyctitheriidae Simpson, 1928Genus Plagioctenodon Bown, 1979

Type species—Plagioctenodon krausae Bown, 1979Included species—Plagioctenodon krausae Bown, 1979;

Plagioctenodon savagei Bown and Schankler, 1982;Plag ioc t enodon dormaa lens i s (Qu ine t , 1964) ;Plagioctenodon rosei (Gingerich, 1987); Plagioctenodonthewisseni sp. nov.

Distribution—Clarkforkian and early Wasatchian (latePaleocene-early Eocene) of the Clarks Fork and Bighornbasins in Wyoming; early Wasatchian (early Eocene) of theGulf Coastal Plain of Mississippi; upper Landenian (earlyEocene) of Dormaal, Belgium.

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Differential Diagnosis—Unique among nyctitheriids inhaving the combination of 1) a relatively high paraconid onthe P4, 2) a P3 that is smaller than the P2 and P4, and 3) ananteriorly canted protoconid on the P3 (see Beard and Dawson2009). Further differs from Asian nyctitheriids (except thepossible nyctitheriine Yuanqulestes qiui [Tong 1997]) in hav-ing a talonid basin and more than one talonid cusp onthe P 4 . A l l Plag io c t enodon spe c i e s ( excep tPlagioctenodon dormaalensis) differ from all speciesclassified as Leptacodon in having a significantly tallerentoconid than hypoconid on the lower molars, ratherthan the two cusps being subequal. Plagioctenodon fur-ther differs from Leptacodon donkroni and Leptacodonmunusculum in having cuspate rather than crestiformparaconids on P4-M1 and a distinct metacone on theP4. Further differs from Leptacodon packi in having adistinct metacone on the P4 and distinct hypocones onthe M1–2 (but see Secord 2008). Further differs fromLeptacodon nascimentoi in having subequal metaconidsand protoconids on the lower molars, rather than theformer being taller and larger than the latter as inL. nascimentoi, and in lacking a pericone on the M1–2

precingula. Further differs from Leptacodon tener inhaving a distinct metacone and protocone on the P3.Further differs from Leptacodon catulus in having amuch greater length to width ratio of the P4.

Plagioctenodon differs from Leptacodon choristus in hav-ing a smaller P3 relative to the other premolars, although it issimilar to L. choristus in having an anteriorly cantedprotoconid on the P3 and a relatively high paraconid on theP4. Plagioctenodon further differs from L. choristus in havinga much greater length to width ratio of the P4, a more devel-oped talonid basin that is longer relative to the rest of the P4, asmaller M3 relative to the M1–2, and a shallowerdentary. Plagioctenodon differs from Leptacodonacherontus in having a smaller P3 relative to the otherpremolars and a higher paraconid on the P4, although itis similar in having an anteriorly inclined protoconid onthe P3 . Plag ioc t enodon fu r the r d i f f e r s f romL. acherontus in having less inflated cusps and morelingually positioned paraconids on the lower molars.

Plagioctenodon further differs from Ceutholestes dolosusin lacking a metaconid on the P3 and having a less molariformP4. It further differs from Placentidens lotus in lacking ametaconid on the P3, having a distinct hypoconulid on thelower molars, and lacking an extension of the cristid obliquato the tip of the metaconid on the lower molars. Further differsfrom Acrodentis rosenorum and Nyctitherium in having ametacone on the P3, wider P4 talonids, less anteriorly com-pressed trigonids on the lower molars, less lingually-positioned hypoconulids on the lower molars, and in lackingpostcingulids on the lower molars. Differs fromLimaconyssus habrus in having a greater P4 talonid

width relative to the trigonid width, having lower-crowned molars, lacking postcingulids on M1–2 andlacking an extension of the cristid obliqua to the tipof the metaconid on the lower molars.

Plagioctenodon differs from all Plagioctenoides,Wyonycteris, and late Eocene European nyctitheriid taxa withthe relevant premolar morphology in possessing a P4paraconid positioned high on the anterior trigonid, althoughit is similar to those taxa in having a reduced P3relative to the other premolars and, with the exceptionsof Plagioctenoides microlestes, Saturninia grandis, andEuronyctia grisollensis, an anteriorly inclined P3

protoconid. Plagioctenodon further differs fromPlagioctenoides and Wyonycteris in having moremolariform P4s, lacking an extension of the cristidobliqua to the tip of the metaconid in the lower molars,and lacking the nyctalodont condition (sensu Menu andSigé 1971) in the lower molar talonids. Further differsfrom Wyonycteris (except for Wyonycteris primitivus)and Pontifactor in lacking mesostyles and dilambdodonty onM1–2. Further differs from Wyonycteris in lacking periconeson M1–2 and differs from Pontifactor in lacking a styloconeand expanded postcingula on M1–2.

Plagioctenodon differs from all late Eocene Europeannyctitheriids (including Amphidozotherium, Cryptotopos,Euronyctia, Paradoxonycteris, and all Saturninia taxa exceptSaturninia ceciliensis) in lacking greatly expandedpostcingula on the P4-M2. Further differs from Cryptotoposin having less anteroposteriorly compressed trigonids on thelower molars, lacking a notch halfway along the length of thecristid obliqua on the lower molars, and lacking lower molarpostcingulids. Further differs from Paradoxonycteris andEuronyctia in lacking upper molar dilambdodonty, lackingan extension of the cristid obliqua to the tip of the metaconidin the lower molars, and lacking a postcingulid on the lowermolars. Further differs from Amphidozotherium cayluxi inlacking a notch in the cristid obliqua of the lower molars,lacking a mesoconid on the cristid obliqua of the lower mo-lars, having a less reduced M3 relative to the M2 size, andhaving more strongly winged para- and metaconules on theM1–2. Further differs from Scraeva hatherwoodensis in lack-ing a mesoconid on the cristid obliqua of the lower molars andhaving less anteroposteriorly compressed trigonids on thelower molars.

Further differs from the middle Eocene EuropeanSaturninia ceciliensis in having the cristid obliqua of thelower molars meet the protocristid lingual to the protocristidnotch, rather than more labially.

Discussion—Bown (1979) ini t ia l ly class i f iedPlagioctenodon in Adapisoriculidae and the original diagno-sis for the genus included: (1) molars that decrease in sizeposteriorly; (2) a P4 with a relatively high paraconid arising onthe anterior surface of the trigonid and a well-developed

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talonid heel; (3) trigonids of the M2 and M3 more constrictedrelative to the trigonid of the M1; (4) the P2 and P3 areprocumbent and not separated by a diastema; (5) the P2 isdouble-rooted and considerably taller than P3; (6) a moremedially situated hypoconulid on the M1; (7) the P

4 is shorteranteroposteriorly relative to the M1; and (8) the protocones onthe upper molars are relatively steep posteriorly. Bown andSchankler (1982) determined that Plagioctenodon was betterclassified in Nyctitheriidae and that the original hypodigm forthe type species, Plagioctenodon krausae, actually includedseveral other taxa. Bown and Schankler (1982) emended thediagnosis to: (1) P2 is larger than P3 with both teeth beingprocumbent and not separated by a diastema; (2) P4 issemimolariform and relatively elongated anteroposteriorly,with a large, anteriorly-projecting paraconid situated high onthe anterior surface of the trigonid and a well-developedtalonid with two or three cusps; (3) M1 and M2 are notsignificantly different in size, whereas M3 is slightly smaller;(4) entoconids on M1 and M2 are relatively taller than thehypoconids and located on the posterolingual margin of themolars; and (5) molars have a shallow hypoflexid and exhibitno vespiform constriction between the trigonids and talonids.Beard and Dawson (2009) later argued that the diagnosisshould focus only on the third and fourth lower premolars,as they felt these teeth contained the most significant morpho-logical differences between Plagioctenodon and Leptacodon.They identified Plagioctenodon by having: (1) a P3 with ananteriorly canted protoconid that is shorter relative to the otherpremolars and (2) a moremolariform trigonid on the P4 than inLeptacodon, on which the paraconid is positioned higher andis less anteriorly shifted (Beard and Dawson 2009).

There has been much uncertainty with the genusPlagioctenodon concerning its relation to Leptacodon. Smith(1996) synonymized the two genera, whereas Beard andDawson (2009) retained the separate genera but transferredLeptacodon rosei and Leptacodon dormaalensis intoPlagioctenodon based upon their updated diagnosis. Thiscreated the first occurrence of a Plagioctenodon species out-side of North America, with the presence of Plagioctenodondormaalensis in the early Eocene of Belgium. Beard andDawson (2009) further suggested that Leptacodon is a prim-itive genus restricted to the Paleocene and only includesLeptacodon tener, Leptacodon packi, and Leptacodonmunusculum. Rose et al. (2012) noted that variation can befound in the diagnostic traits of Beard and Dawson (2009)within a single species and also pointed out that the lowerpremolars are often missing in specimens, making identifica-tion of those fossils impossible. The derived traits listed inpreviously published diagnoses of Plagioctenodon imply thegenus is monophyletic. The majority of traits used to diagnoseLeptacodon, such as sectorial cusps, relatively low trigonidswith a centrally-positioned hypoconulid, distinct paraconids,and absence of a mesostyle (Matthew and Granger 1921;

McKenna 1968; Bown and Schankler 1982; Rose et al.2012), are probably primitive. Consequently, Leptacodonmay be paraphyletic with Plagioctenodon nested within it,or a polyphyletic grouping distributed throughout the familyNyctitheriidae.

Plagioctenodon rosei (Gingerich, 1987)(Fig. 2)

Cf. Leptacodon packi Rose, 1981; Leptacodon roseiGingerich, 1987

Holotype—UM71650, left dentary with P2- M3, describedin Rose (1981: Fig. 11).

Distribution—Clarkforkian and possibly earlyWasatchian.

Diagnosis—See Rose (1981) and Gingerich (1987).Emended description—Several specimens of P. rosei

have been recovered from the freshwater limestone with com-plete dentitions, which allows for description of their anteriorteeth (e.g., UF 303728; UF 303729; UF 303730). The dentalformula is 3-1–4-3/3-1–4-3.

Fig. 2 Micro-CT scan images of anterior dentitions of Plagioctenodonrosei in labial view. a, Right dentary (I1-P4) and palate (I1-P4) of UF303728. b, Left dentary (I1-M1)and palate (I2-P4) of UF 303729(reversed), lingual view of R M1–3 visible

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The upper incisors of P. rosei are small and bi-lobed, withone main anterior cusp and a small posterior cusp (Fig. 2).They show a slight decrease in size posteriorly (Fig. 2a). Theanterior-most cusp of the I1 curves posteriorly near the tip andcomes to a rounded point. The smaller posterior cuspule of I1

points ventrally and is crestiform. The I2–3 are similar inmorphology to that of C1 and P1 in having larger rectangularanterior cusps and considerably smaller posteriorcuspules in labial view. In I2–3, however, the anteriorcusp is less curved and has a more dorsoventral orien-tation. The upper canine is significantly larger than thesurrounding teeth and has a single broad root, a largeconical cusp that curves slightly posteriorly, and a muchsmaller and shorter posterior cusp relative to the anteriorcusp. The P1–2 are both double-rooted, labiolinguallycompressed, and consist of a triangular anterior cuspand a much smaller posterior cusp in labial view. TheP2 is slightly taller than the P1. The P3 has three rootsand is dominated by a large, central paracone. It has asmall parastyle anterior to the paracone and a relativelylarger metastyle posteriorly that is connected to theparacone by the postparacrista. There is also a smallprotocone that is directly lingual to the paracone. Themetacone shows up variably as a small swelling on thepostparacrista about midway between the paracone andmetastyle (UM 39843, UF 303728) and is completelyabsent in some specimens (UF 303729).

The lower incisors are small, procumbent, roughly equal insize, medial-laterally compressed, and multi-lobed (Fig. 2b).The I1 is the tallest of the lower incisors but is shorter in lengththan the I2. It has three lobes and is flat on its medial surface,which tapers dorsoanteriorly to form the anterior-most lobe ofthe tooth. This lobe continues to curve posterolaterally,becoming broad and rounded. A second lobe is postero-lateral to the first at about the same height, but isshorter in length. The tooth ends posteriorly in the thirdcuspule, which is much smaller and shorter than theother two. The I2 is lower-crowned than the I1 and isthe longest anteroposteriorly of the lower incisors. Aspreviously described by Rose et al. (2012), it has fivelobes, the first of which is the longest anteroposteriorly;the following three lobes are rectangular in shape andabout the same size, whereas the fifth and final lobe issmall and is sometimes absent, possibly due to wear.The third incisor has three lobes, although the separa-tion between the first two is difficult to distinguish inspecimens exhibiting wear. The gap between the secondand third lobes is much larger, making the smaller,posterior lobe easier to distinguish from the first two.The lower canine is larger than the incisors and is abouttwice the size of the P1. The C1 and P1 are similar inmorphology in being dominated by a large, rectangularcusp that is oriented about 45° to the long axis of the

jaw and possessing a very small posterior cuspule at thebase of the tooth. The P2-M3 were previously describedby Rose (1981) as cf. Leptacodon packi.

Comparisons—Incisor and canine morphology is knownfor few nyctitheriid taxa. North American taxa with associatedincisors or canines include the late Paleocene P. rosei (Roseet al. 2012; this publication), Plagioctenodon thewisseni (thispublication), Ceutholestes dolosus (Rose and Gingerich1987), and possibly the earliest Eocene Leptacodon donkroni,although the isolated I2 attributed to it is from a locality thatalso contains the small-bodied Plagioctenoides microlestesand Plagioctenoides tombowni (Rose et al. 2012). SeveralEuropean taxa have also been documented with incisors orcanines, including the middle to late Eocene Saturniniacarbonum (Sigé and Storch 2001), Saturninia grandis (Sigé1976), Cryptotopos beatus (as Saturninia beata) (Sigé 1976),and Euronyctia grisollensis (as Saturninia grisollensis) (Sigé1976), the late Eocene through early Oligocene Saturniniagracilis (Sigé 1976) and Amphidozotherium cayluxi (Sigé1976), and the early Oligocene Cryptotopos communis(Ziegler 2007).

There are very few nyctitheriid species with documentedupper incisors. Sigé (1976: Fig. 60) attributed a possible I2–3

toC. beatus (as Saturninia beata). The teeth described by Sigé(1976) are similar in morphology to the I2–3 ofP. rosei (Fig. 2),supporting their attribution to a nyctitheriid taxon.Plagioctenodon thewisseni is the only other nyctitheriid forwhich upper incisors have been recovered, with a referred I1-I3. Among these three taxa, all upper incisors have a mainlabiolingually-flattened cusp with a much smaller posteriorcusp and in terms of overall size, the I2 is slightly smaller thanthe I1 but considerably larger than the I3. The main differencebetween P. rosei, C. beatus, and P. thewisseni is the shape ofthe large, anterior cusps of the incisors. The anterior cusps ofC. beatus have a more triangular shape in labial view, whereasthose of P. rosei are more squared off posteriorly and look likean oblique rectangle, and in P. thewisseni they are like ananteriorly canted triangle, with a convex anterior face and aconcave posterior face.

In P. rosei, there is some variability seen in the presence ofthe upper canine posterior cuspule—it is absent in at least onespecimen, UF 303729, but present in UF 303728 and UF303730. The upper canines of P. rosei specimens UF303728 (Fig. 2a) and UF 303730 are similar to the uppercanine referred to P. thewisseni (Fig. 3) in having a largeanterior cusp with a small, posterior cuspule. Five teeth ante-rior to the P4 are illustrated for the holotype of Leptacodontener, but due to crushing and displacement, the positions ofthose teeth are not certain. The two anterior teeth, “A” and “B”(McKenna 1968: Fig. 2), are both large and single-rooted andcould potentially be the canine. “A” does not have a posteriorcuspule and is morphologically similar to the upper canine ofthe P. rosei specimen UF 303729 (Fig. 2b), whereas “B” does

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have a posterior cuspule and resembles the upper canines ofboth other P. rosei specimens and P. thewisseni.

The morphology of the anterior upper premolars is verysimilar between P. rosei (Fig. 2) and P. thewisseni(Figs. 3 and 4), with the P1 and P2 both double-rootedand having a large, triangular, labio-lingually flattenedanterior cusp and a small posterior cuspule. There isalso a significant increase in size between the P1 and P2

in both taxa. In the upper anterior teeth described byMcKenna (1968), “C” and “D” are most similar inmorphology to the P1 and P2, respectively, of knownnyctitheriid taxa, as was predicted (McKenna 1968).

The P3 morphology does not appear to be highlyconstrained in nyctitheriid species. In P. rosei (Fig. 2), thepresence of a metacone is variable; it is present as a smallswelling on the postparacrista in UF 303728 (Fig. 2a) and UF303730, whereas it is absent in UF 303729 (Fig. 2b). In thetwo specimens with a P3 known for P. thewisseni (Figs. 3 and4), the metacone is consistently present, but the morphologyof the protocone varies. The P3 protocone of the holotype(UM 86725: Fig. 4) is considerably smaller and less linguallyextended than the protocone in UF 294696 (Fig. 3). MultipleP3s are documented for C. beatus (Sigé 1976: Fig. 61) that alllack metacones but vary greatly in shape. The P3 ofCryptotopos hartenbergi (Sigé 1976: Fig. 47) is dissimilar inmorphology to those of C. beatus and strongly resem-bles the P3s seen in most Plagioctenodon specimens,with a clearly defined metacone and a small protoconethat is not lingually extended.

At least one P3 is documented for Acrodentis rosenorum(Christiansen and Stucky 2013: Fig. 2a-b), Nyctitheriumkrishtalkai (Christiansen and Stucky 2013: Fig. 2c-d), andS. gracilis (Sigé 1976: Figs. 3 and 11). Like C. beatus, thesethree taxa do not possess a metacone on the P3. Tooth “E” of

L. tener (McKenna 1968: Fig. 2) is almost certainly the P3; it isdominated by the paracone and lacks a metacone, but it isunusual in that it does not appear to have a distinct protocone.The lack of a protocone on the P3 separates L. tener frommostother nyctitheriids and may represent the ancestral state, be-cause this is the oldest nyctitheriid known with a P3. However,it is important to note that the P3 of the L. tener holotype wasdestroyed in preparation and it is impossible to verify thismorphology other than through examination of a photograph(McKenna 1968: Fig. 1). The only other nyctitheriids that lacka protocone on the P3 likely lost that cusp secondarily. The P3

of the European Cryptotopos communis from the Oligoceneconsists mostly of a large paracone with little to no parastyleor metastyle and a small lingual bulge (Ziegler 2007: Fig. 3.3).The late Eocene European Paradoxonycteris soricodon is

Fig. 4 Micro-CT scan images of left (P2-M3) and right (P2-M3) maxillaeof Plagioctenodon thewisseni (UM 86725). a, Left and right palatearticulated in occlusal view. b, Left palate in occlusal view. c, Leftpalate in lingual view. d, Right palate in occlusal view. e, Right palatein lingual view

Fig. 3 Micro-CT scan images of left maxilla of Plagioctenodonthewisseni with C1-M3 (UF 294696). a, Labial view. b, Occlusal view

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reported as having a single-rooted, unicuspid P3 (Revilliod1922), although that tooth has since been lost (Hooker andWeidmann 2000).

The morphology of the P. rosei I1 (Fig. 2b) differs from thatof the other two nyctitheriid species with known I1s,A. cayluxiand Ceutholestes dolosus. The I1 of A. cayluxi is longer andtaller than its I2 and I3 and it appears to have a singlelarge anterior lobe with a small accessory labial cuspule(Sigé 1976: Fig. 95A-C), whereas in C. dolosus, the I1is shorter in both length and height than the I2 and ithas four lobes (Rose and Gingerich 1987: Figs. 1, 2 and3).

The morphology observed in the I2 is the same as thatreported for P. rosei by Rose et al. (2012), in which theydocument five lobes with the posterior-most one being smalland acute.We have found in our sample size that the fifth cuspis sometimes absent, although this is likely due to wear ordamage. Whereas other nyctitheriids exhibit a very similarmorphology, all other taxa outside the Plagioctenodon genuswith known I2s, including Ceutholestes (Rose and Gingerich1987: Figs. 1, 2 and 3), S. carbonum (Sigé 2001: Fig. 1),Euronyc t ia gr i so l l en s i s (S igé 1976 : F ig . 27 ) ,Amphidozotherium (Sigé 1976: Fig. 95), and tentativelyL. donkroni (Rose et al. 2012: Fig. 21I-J), only possess fourlobes on that tooth, lacking the acute, posterior-most cuspule.A possible exception is C. communis, which was attributed I2swith both four and five lobes, although it was also suggestedthat the lower incisor with five lobes could represent either thenot-yet-identified I1 morphology or is an I2 exhibiting an“autapomorphy” (Ziegler 2007). The incisor with five cusps(Ziegler 2007: Fig. 2.5) does not look very similar to themorphology of I1s from other nyctitheriid taxa and bears astriking resemblance to the I2 of P. rosei. It is much morelikely that the I2 of C. communis is polymorphic or the four-and five-lobed incisors represent I2s of two differentnyctitheriid taxa. Rose et al. (2012) commented that the linedrawing of A. cayluxi in Sigé (1976: Fig. 95) appears toexhibit a short, fifth cuspule at the posterior base of the tooth,but the text states that the taxon only has four cuspules. Theonly two nyctitheriids with definitive five-lobed I2s areP. rosei and P. thewisseni, representing a potential synapomor-phy for the genus.

The I3 of S. gracilis (Sigé 1976: Fig. 4) and S. grandis (Sigé1976: Fig. 69) is nearly identical to that of P. rosei (Fig. 2) inhaving three lobes, but C. beatus (Sigé 1976: Fig. 56),C. communis (Ziegler 2007: Fig. 2.7), A. cayluxi (Sigé1976: Fig. 95), and S. carbonum (Sigé 2001: Fig. 1) areall more similar to that of P. thewisseni (Fig. 5) inhaving just two lobes. The I3 of P. thewisseni is verysimilar to that of the more worn P. rosei specimens,suggesting that its unworn state might have three lobesin similar configuration to those seen inP. rosei. Therefore, thetwo lobes found in some of the taxa may be a true

morphological state or it could be due to wear on the anteriortwo lobes that make them appear to be merged.

The large, procumbent anterior cusp and small posteriorcuspule of the lower canine of P. rosei (Fig. 2b) is shared withS. gracilis (Sigé 1976: Fig. 5), S. grandis (Sigé 1976: Fig. 70),S. carbonum (Sigé 2001: Fig. 1), C. beatus (Sigé 1976:Fig. 55), C. hartenbergi (Sigé 1976: Fig. 55), C. communis(Ziegler, 2007: Fig. 2.8), and A. cayluxi (Sigé 1976: Fig. 95).Ceutholestes dolosus also has a similar morphology, althoughthe area in which the basal cuspule is located is more of aflattened shelf (Rose and Gingerich 1987: Fig. 1). The caninesof these nyctitheriids are unlike those of Maelestes gobiensisand Adunator minutus, which both lack the posterior shelf.The lower canines of Nyctitherium velox and Nyctitheriumkrishtalkai have been described as “primitive (didelphoid)”(Robinson 1968: 130) and “round in cross-section, primitive,and single-rooted” (Christiansen and Stucky 2013: 7), respec-tively. Both of these teeth appear to be damaged and thereforewe cannot assess whether they were more similar in morphol-ogy to the other nyctitheriids or the outgroup taxa used in ourcladistic analysis.

Discussion—Leptacodon rosei was transferred toPlagioctenodon by Beard and Dawson (2009) based on char-acters of the third and fourth lower premolars including arelatively smaller, anteriorly canted P3 and a relatively highparaconid on the P4 (see genus discussion of Plagioctenodon inthis paper). The species is primarily known from theClarkforkian (Gunnell et al. 2008) but it may be present in theTiffanian (Secord 2008) and the Wasatchian (Rose et al. 2012).

The largest sample of P. rosei, including the holotype, wasrecovered from the Cf-2 locality SC-188. Although most ofthe fossils from SC sites were collected via surfaceprospecting, this site was screen-washed, which led to therecovery of some of the most complete jaws known for thisspecies (Rose 1981; Gingerich 1987), including at least onedentary with I1-P4 (UM 77030). Lower incisors are alsoreported in the specimens USNM 539484 and UM 82389 byRose et al. (2012). Although some anterior teeth of P. roseihave been found by screen-washing and surface prospecting,those recovered from limestones are unique in being part ofexceptionally complete specimens, often with the upper andlower jaws in association and the full dental formula preserved(e.g., Fig. 2).

Plagioctenodon thewisseni sp. nov.(Figs. 2 and 3, Table 2)

“Cf. Plagioctenodon krausae”: Rose, 1981:41, Figs. 12and 13; Gingerich, 1987:304

“Plagioctenodon bowni”: nomen nudum, Bloch, 2001:65,Fig. 5

Etymology—Named for Professor J. G. M. Thewissen ofNortheast OhioMedical University who in 1986 as a graduate

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student working as a member of the University of Michiganfield party, discovered the freshwater limestone nodule fromwhich the holotype was extracted. Other notable fossils fromthat same nodule include a remarkable skull and skeleton ofPlesiadapis cookei (Gunnell and Gingerich 1987; Gingerichand Gunnell 1992, 2005). The holotype (UM 86725) ofP. thewisseni was first mentioned as an “exceptionallycomplete nyctitheriid” by Gingerich (1987) and referredto “Cf. Plagioctenodon krausae”. It was later discussedin the dissertation of J. I. Bloch (2001) in which it was referredto a new species “Plagioctenodon bowni” as a nomen nudum.Since that time, the specific name “bowni” has been used inanother closely related nyctitheriid species name(Plagioctenoides tombowni; Rose et al. 2012) and thus notused again here to avoid confusion.

Holotype—UM 86725: Left dentary with crowns of I2-P1and P3-M3; right dentary with crowns of C1-M3; right and leftmaxillae with crowns of P2-M3 (Figs. 2 and 3).

Type Locality—University of Michigan (UM) LocalitySC-117, Willwood Formation, Clarks Fork Basin, Wyoming

(See [Rose 1981] for more detailed locality information) fromthe late Clarkforkian part of the Paleocene epoch (Copecioninterval zone [Cf-3], approximately 56 Ma; Secord 2008).

Referred Specimens—SC 117: UM 39873, right (R)dentary with C1, P3-M2. SC 62: UM 83931, R dentary withbroken P2, P3-M3; UM 82576, R edentulous dentary withroots for M1 and P3, associated with loose R C1, broken RP1, R M2-M3 (trigonid), R I1, and R maxilla with I2-I3. SC 29:UM 76906, left (L) I2; UM 76920, R M2 labial fragment. SC327: UF 289746, R I2, R P4, L C1, partial skeleton; UF289747, R maxilla with P3-M3, L maxilla with P4-M3, Ldentary with P1-M3, partial skeleton; UF 294696, L maxillawith C1-M3, R P4, R dentary with M1-M3.

Diagnosis—Differs from all other Plagioctenodon speciesin being smaller, having larger and more anteriorly projectingparaconids on P3–4, a more anteroposteriorly elongated P4,and a more reduced precingulum on the upper molars. Itfurther differs from P. dormaalensis in having more acutecusps, larger, more anterolingually shifted molar paraconids,taller entoconids than hypoconids, and two mental foramina

Fig. 5 Micro-CT scan images ofleft (I2-P1, P3-M3) and right (C1-M3) dentary of Plagioctenodonthewisseni (UM 86725). a, Leftdentary in labial view. b, Leftdentary in lingual view. c, Leftdentary in occlusal view. d, Rightdentary in labial view. e, Rightdentary in lingual view. f, Rightdentary in occlusal view

J Mammal Evol

rather than one. It further differs from P. rosei in having moreelongate lower premolars with a greater exaggeration in theanterior cant of the protoconids. It further differs fromP. krausae and P. savagei in having narrower molar talonidsrelative to the trigonids, and more anteriorly positionedentoconids in relation to the hypoconulid.

Age and Distribution— All localities are located in theWillwood Formation, late Clarkforkian North AmericanLand Mammal Age Copecion interval zone (Cf-3),which spans 56.22-55.8 Ma (Secord 2008). UM locali-ties SC-117 (at the stratigraphic level of 1370 m abovethe Cretaceous-Paleogene boundary in the BighornBasin), SC-62 (1380 m); SC-29 (1385 m); SC-327(1420 m) of the Clarks Fork Basin, Wyoming, UnitedStates of America.

Measurements—see Table 2.Description—The holotype is relatively complete and

shows that P. thewisseni has small, sectorial teeth set in ashallow, elongate dentary. The lower dental formula is 3-1-4-3 and the lower molar series shows a slight decrease in sizefrom M1 to M3. The dentary contains two mental foramina;the anterior foramen is located beneath the P2 and the posteriorforamen is below the posterior root of the P3.

The left dentary preserves the crowns of I2–3 and an alve-olus for I1. The lower incisors appear to be similar in size andare procumbent and multi-lobed or scalloped. The tip of I2 isbroken but there is a small, bulbous cuspule at theposterolingual extent of the tooth crown with two lobes situ-ated anterobucally above it that curve anteriorly. A completeI2 referred to P. thewisseni (UM 76906) was first described byGingerich (1987) as “Cf. Plagioctenodon krausae” in whichhe stated that it has five cusps and is similar in appearance tothat of the European nyctitheriids Saturninia andAmphidozotherium. The tooth has since been broken, but afterexamination, we agree with this assessment. The thirdincisor is more worn than the second, but it appears tohave been slightly smaller than I2 and had at least twolobes.

The lower canine is procumbent and only slightlyenlarged relative to the incisors and P1. It is dominatedby one large cusp that is laterally compressed and morespatulate than conical, but also has a small posteriorbasal cuspule.

The P1 is similar in shape to that of the canine; it isprocumbent with a large, squared-off spatulate anterior cuspand a much smaller posterior basal cusp. The P2 and P3 aresimilar in shape but the former is larger than the latter. Theyare both double-rooted and dominated by a large, anteriorlycanted protoconid. There is a small, anteriorly projectingparaconid located on the anterior surface of the protoconid,situated relatively high on the P2–3, about halfway between thebase of each tooth and the tip of the protoconid. A crest runsposteriorly from the tip of the protoconid to the base of the

crown, where it ends in a single posterior cusp. There is notalonid basin on either the P2 or P3.

The P4 is elongate, with a length almost twice that of thewidth. It is semi-molariform with a large, anteriorly projectingparaconid that arises high on the anterior face of the trigonid,similar to the condition in other species of Plagioctenodon.The paraconid is joined to the protoconid by a v-shapedparacristid below which, on the buccal surface of the crown,there is a slight anterior bulge that occupies a similar area ofthe precingulid as on the lower molars. The metaconid isrelatively large, being only slightly smaller and shorter thanthe protoconid. The talonid is nearly equal in width to that ofthe trigonid, although slightly shorter anteroposteriorly. It hasthree distinct cusps. The hypoconid and entoconid aresubequal in size but the latter is slightly taller. Thehypoconulid is smaller than the other talonid cusps and issituated midway between them and slightly posterior. Thecristid obliqua is strong, extending from the hypoconid andclimbing about halfway up the posterior wall of the trigonidwhere it ends immediately below the notch in the protocristid.

The trigonid is slightly narrower than the talonid on theM1,subequal in width on the M2, and wider than on the M3. Theparaconids of the lower molars project anteriorly and aresituated lingual to the midline on the trigonid. A robustprecingulid is present on the anterolabial surface of themolars,terminating posteriorly below the protoconid. The metaconidand protoconid are subequal in height. The base of theprotoconid has a larger circumference than that of themetaconid of M1, whereas the protoconid and metaconid aresubequal in circumference for the M2 and M3. The talonids ofthe lower molars have three distinct cusps; the entoconid issimilar in length and width to the hypoconid, whereas thehypoconulid is somewhat smaller than both. The entoconid istaller than the hypoconid and is positioned anterolingually tothe hypoconulid. The hypoconulid is positioned slightly lin-gual to the midline. The cristid obliqua extends from thehypoconid and climbs a short way up the posterior surfaceof the protoconid, just labial to the notch in the protocristid.

Associated crowns of I1–3 were recovered from a limestonein association with lower teeth that are referred toP. thewisseni(UM 82576). The upper incisors decrease in size posteriorlyand are similar to each other in morphology, with a largeanterior cusp that is labiolingually compressed and asymmet-rically shaped with the anterior edge bulging anteriorly, and asmall posterior cuspule. The C1 of P. thewisseni is single-rooted and the crown is about twice the height of the P1, hasa large primary cusp with a slight posterior curve at the crest,and a small posterior basal cuspule. Other than its smaller size,the P1 is nearly identical to the P2; both have a large, erectparacone and a much smaller posterior basal cuspule. The P3

has a conical paracone with a strong postparacrista fromwhich a small metacone swells. A crista continues posteriorlyfrom the metacone and extends to a metastyle that is only

J Mammal Evol

slightly smaller than the metacone. There is a distinct parastylethat is not connected to the paracone. The protocone is smalland similar in size to the metacone; it is situated closely to theposterolingual side of the paracone.

The P4 paracone and metacone are appressed to one anoth-er and similar in size, but the paracone is taller. There is adistinct, conical parastyle that is separated from the paraconeand a similar-sizedmetastyle that is connected to the metaconeby a postmetacrista. The stylar shelf is shallow with no dis-cernible ectoflexus and oriented anterolingually-posterobuccally. The protocone is shifted anteriorly to theparacone. A small trigon basin is present but there are noconules. There is a small precingulum and postcingulum,whereas the hypocone is vestigial to absent.

The M1 and M2 are similar in form with the M1 beingslightly larger. The paracone and metacone are subequal insize and height, joined by a rectilinear centrocrista. The stylarshelf is shallow with the parastyle and metastyle as the onlystylar cusps. The ectoflexus of the M2 is deeper than that ofM1. There is a small conical parastyle that is anterolabial to theparacone and connected to it by a small preparacrista. Theparastyle projects anteriorly on theM1 andmore anterolabiallyon the M2. The metastyle is similar in size to the parastyle andis posterolabial to the metacone, connected to it by a strongpostmetacrista. The paraconule and metaconule are presentand strongly winged by their respective pre- and post- conulecristae. The paraconule is located anterior to the paracone andprotocone and situated closer to the latter. The preparaconulecrista forms an anterior ridge on the crown that extendslabially, almost reaching the parastyle, whereas thepostparaconule crista terminates at the base of theparacone. The metaconule is located about halfway be-tween the me t acone and p ro tocone and thepremetaconule crista ends at the anterior edge of themetacone, whereas the postmetaconule crista extendsposterolabially, stopping just short of the metastyle.The protocone is situated lingual to the paracone andprojects anteroventrally. A small precingulum andpostcingulum are present, the former extends from theprotocone to the paraconule and the latter from justlingual to the protocone to the metaconule. Thepostcingulum has a small, conical hypocone that issituated posterolingual to the protocone. The M3 has ataller paracone than metacone, a prominently projectingparastylar shelf, no metastyle, distinct but small para-and metaconules, a small precingulum, and nopostcingulum.

Some of the referred specimens (UF 294696, UF289746, UF 289747) include cranial and/or postcranialelements outside of the scope of this study and are notdescribed here.

Comparison—For the most part, nyctitheriids for which itcan be documented have a 3-1-4-3/3-1-4-3 dental formula. It

is possible that the holotype of L. tener had five upper premo-lars (McKenna 1968; Krishtalka 1976), but the specimen isbadly crushed and not fully developed (McKenna 1968). Thecondition of two mental foramina in the dentary appears to bethe primitive condition for Nyctitheriidae; the reduction to asingle foramen is derived in some clades. For those speciesthat have at least one dentary complete enough to be assessed,the Asian nyctitheriids, all species classified as Leptacodon,Wyonycteris , Plagioctenoides , Ceutholestes , andLimaconyssus, and most species of Nyctitherium andPlagioctenodon, including P. thewisseni, have two mentalforamina. One of the foramina has been lost in Nyctitheriumvelox, Acrodentis rosenorum, Plagioctenodon dormaalensis,and all of the late Eocene European nyctitheriids, includingAmphidozotherium, Saturninia, Cryptotopos, Scraeva, andEuronyctia. Although most of the specimens of P. rosei havea similar condition to that of P. thewisseni, with mentalforamina below P2 and the posterior root of P3, at leasttwo of them (UM 76498 and UF 303729) only have asingle, larger mental foramen centered under the anteriorroot of the P3. The nyctitheriid taxa with only oneforamen all have it similarly positioned below the P3in contrast to the variable position of the mental foram-ina in nyctitheriid taxa with two.

For comparisons of I1-P3 and I1-P1, see the correspondingsection for P. rosei. The morphologies of the P2 and P3 (Fig. 5)are typical for nyctitheriids in having a single large protoconidwith a smaller anterior and posterior cusp. Nyctitheriids thatvary from this basic configuration are Ceutholestes dolosus(Rose and Gingerich 1987: Fig. 1) and Placentidens lotus(Russell et al. 1973: Fig. 12D), which both have an additionalcusp, a small metaconid appressed to the protoconid on the P3.Some nyctitheriids, including Wyonycteris richardi (Smith1995: Fig. 2), both Plagioctenoides species (Rose et al.2012), Amphidozotherium cayluxi (Sigé 1976: Fig. 95), andEosoricodon terrigena (Lopatin 2005: Fig. 2), exhibit a moresimplified morphology in which the P2, and sometimes the P3,may lack the anterior cusp or is single-rooted rather thandouble-rooted. The asymmetrical, anterior bulging of theprotoconid on both premolars is a variable trait in the family,however. This condition is seen in several clades, including allPlagioctenodon species (Fig. 5; Beard and Dawson 2009),Leptacodon acherontus (Secord 2008: Fig. 33), Leptacodonchoristus (Secord 2008: Fig. 36), W. richardi (Smith 1995:Fig. 2), most Saturninia and Cryptotopos species (e.g., Sigé1976), and in Oedolius perexiguus (Lopatin 2006: plate 4,Fig. 1), whereas many other nyctitheriids and the outgrouptaxa have a more symmetrical, erect protocone. The smallersize of the P3 compared to that of the surrounding premolarsappears to be a derived trait that occurs only in thePlagioctenodon, Wyonycteris, Plagioctenoides, and late-oc-curring European nyctitheriid clades and may haveevolved just once in the family’s history (see Node L

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in Fig. 6 and Appendix 2). In all other nyctitheriids, thelower premolars generally increase in size posteriorly.

The P4 of Plagioctenodon exhibits one of the onlydefinitive synapomorphies for the clade, a relativelyhigh P4 paraconid, but this trait does occur in the othernon-Plagioctenodon nyctitheriid taxa Leptacodonchoristus (Secord 2008: Fig. 36), Ceutholestes dolosus(Rose and Gingerich 1987: Fig. 1), Limaconyssushabrus (Gingerich 1987: Fig. 20), Asionyctia guoi(Missiaen and Smith 2005: Fig. 1), and in someLeptacodon munusculum specimens (e.g., Gingerichet al. 1983: Fig. 2c; Krause and Gingerich 1983:Fig. 11). In other nyctitheriids the P4 paraconid is loweron the anterior surface of the trigonid. The P4 ofP. thewisseni is semimolariform, with a relatively largemetaconid and a clearly defined talonid basin that isnearly the same width as the trigonid, just like the P4sof the other Plagioctenodon species. Some variationexists in the number of the talonid cusps, however.Although all known specimens for P. thewisseni,P. dormaalensis (Smith 1996), and P. savagei (Bownand Schankler 1982) have three talonid cusps, the sam-ples for P. rosei and P. krausae include P4s withtalonids that have both two and three cusps (see Bown

1979; Rose 1981). The last two species also have thelargest sample sizes in Plagioctenodon, so it is possible theremay also be some two-cusped P4 talonids found for the otherPlagioctenodon species upon an increase in sample size. TheP4 of P. thewisseni is unique among other Plagioctenodonspecies and most other nyctitheriids in having a noticeablylower width to length ratio: 0.47 and 0.46 for the holotype andaveraged across all referred specimens, respectively (calcula-tions made from Table 2). This makes it one of the fewnyctitheriid species with a length to width ratio below 0.5;the only other nyctitheriids are Leptacodon proserpinae (VanValen 1978), Leptacodon tener (McKenna 1968: Fig. 4),Wyonycteris primitivus (Beard and Dawson 2009), Edzeniuslus (Lopatin 2006: table 18), and Oedolius perexiguus(Lopatin 2006: table 15). A low P4 width to length ratio islikely a primitive trait for Nyctitheriidae, because this is thestate of the outgroup (Maelestes gobiensis [Wible et al. 2009:table 1]), the oldest proposed nyctitheriid (L. proserpinae),one of the oldest definitive nyctitheriids (L. tener), anyctitheriid exhibiting unusually primitive characters for itsclade (W. primitivus, see Beard and Dawson 2009), and twoAsian nyctitheriids (E. lus and O. perexiguus). The presenceof this trait in P. thewisseni is not necessarily retention of aprimitive feature, however, because the extreme anterior

Fig. 6 Strict consensus of twomost parsimonious trees for thephylogenetic analysis ofNyctitheriidae. Tree length = 330steps; CI = 0.282; RI = 0.601.Bremer supports are indicated bythe number above the lines andthe letter below the lines representkey nodes listed in Appendix 2

J Mammal Evol

projection of the paraconid on the P4 accounts for part of theunusual length of the tooth.

The lower molars are generally similar between thePlagioctenodon species. P. thewisseni has larger and moreanteriorly projecting paraconids than the other species(Fig. 5), but otherwise its molars look nearly identical to thoseof P. rosei (Rose 1981: Fig. 11). The lower molars ofP. thewisseni, P. rosei, P. krausae, and P. savagei differ fromP. dormaalensis in having taller entoconids than hypoconids,whereas they are equal in height in P. dormaalensis (Smith1996). The lower molars of P. krausae and P. savagei differfrom those of other Plagioctenodon species in having theentoconid located along the posteriormost edge of thecrown (Bown and Schankler 1982); it is more anteriorlylocated in the other taxa. Although the lower molars ofnyctitheriids can generally be classified as havingsubequal (within 5%) trigonid and talonid widths, thereare subtle differences in the proportions of the trigonidand talonid within the tooth row. The M1 and M2 ofP. thewisseni are very similar in morphology, but thetrigonid is slightly narrower than the talonid in the M1,whereas it is subequal in the M2. This trend is sharedwith P. rosei (Rose 1981: table 4) and someP. dormaalensis (Smith 1996: Figs. 2 and 3) specimens,as well as Nyctitherium velox (Krishtalka 1976: table 3),Ceutholestes dolosus (Rose and Gingerich 1987: table1), Placentidens lotus (Russell et al. 1973: Fig. 12),Wyonycteris chalix (Gingerich 1987), and Wyonycterisrichardi (Smith 1995: tableau p. 928).

The P4 of P. thewisseni is nearly identical to those ofP. rosei and P. dormaalensis. All three have a smallpostcingulum, but P. dormaalensis has a clearly-defined,small hypocone, whereas P. thewisseni and P. rosei donot.

The upper molars of P. thewisseni differ from those ofP. rosei, P. krausae and P. dormaalensis in having a smallerprecingulum, but the size of the precingulum is quite variableacross the family (Appendices 3–4: Character 55).Otherwise, the species classified as Plagioctenodon allhave very similar upper molars that can be differentiatedfrom other nyctitheriid clades mostly by their lack ofderived features, including 1) the mesostyle otherwisefound in a l l Wyonyc ter i s spec ie s o the r thanW. primitivus, 2) the dilambdodonty otherwise seen inPontifactor bestiola, Wyonycteris chalix, Wyonycterisrichardi, Paradoxonycteris, and the Euronyctia species,3) the pericone otherwise found in Wyonycteris,Cryptotopos, Placentidens lotus, and several Saturniniaspecies, 4) a reduction in para- and metaconule size andwinging otherwise seen in Nyctitherium and many lateEocene European nyctitheriids, and 5) a greatly expand-ed postcingulum otherwise found in Nyctitherium,Pontifactor, and the late Eocene European nyctitheriids.

Discussion— Plagioctenodon thewisseni is similar to otherPlagioctenodon species in having an anteriorly inclinedprotoconid on P2, a reduced P3 with an anteriorly cantedprotoconid and a P4 paraconid that is positioned rela-tively high on the trigonid. Plagioctenodon thewisseni isone of the smallest nyctitheriids known, which mayexplain its limited sample size in the otherwise fossilif-erous localities of the Clarks Fork Basin. The body sizeof P. thewisseni is estimated to be 5.01 g and 7.49 g(Table 3) based on the M1 and M1 crown areas, respec-tively, using the regression functions of Bloch et al.(1998). The true body mass is likely to be closer tothe estimate provided by the M1 because that tooth isargued to be a better mass estimate than the M1

(Gingerich 1982). Plagioctenodon thewisseni is thesmallest Plagioctenodon species, with a body mass~30% less than that of the next smallest species,P. dormaalensis, which is estimated here to be 7.17 gusing M1 dimensions. The only North Americannyctitheriids with smaller estimated body masses thanP. thewisseni based on the M1 are Leptacodon donkroni,Plagioctenoides microlestes, and Saturninia mamertensis.Based on theM1, Saturninia gracilis andWyonycteris microtisare smaller, although S. gracilis is estimated to be larger usingthe M1 equation and W. microtis may not be a nyctitheriidbased on the results of our cladistic analysis. Plagioctenoidestombowni is likely to be smaller than P. thewisseni, as well;although there is not a complete M1 or M1 known forP. tombowni, other teeth are nearly the same size as those ofP. microlestes (Rose et al. 2012).

Fossils similar to those of P. thewisseni have been inmuseum collections for over thirty years. Rose (1981)described an isolated P4 (UM 69942), M1 (UM 71689),and M2 (UM 71686) from late Clarkforkian localities inthe Clarks Fork Basin and suggested that they repre-sented “a slightly smaller Clarkforkian predecessor ofearly Wasatchian P. krausae.” These teeth were referredto as cf. Plagioctenodon krausae (Rose 1981:42) andthey could be included in the P. thewisseni hypodigmbased on their similar temporal range, size, and mor-phology (see Rose 1981: Fig. 12–13). Additionally,Gingerich (1987) referred half of an upper molar andan I2 to “Cf. Plagioctenodon krausae,” stating that it“ r e s emb l e s Lep t acodon a s much a s i t doe sPlagioctenodon, and definitive placement of all of thesespecimens must await study of the new material”(Gingerich 1987:304). Finally, Secord (2008) referredseveral isolated teeth from the Y2K Quarry (Ti-5b) toPlagioctenodon sp. and noted that they closely resemblethe “Cf. Plagioctenodon krausae” of Rose (1981) andGingerich (1987). We agree that the lower molars havestrong similarities to P. thewisseni, particularly UM109346, but the lack of the diagnostic P4, the overly

J Mammal Evol

Table 3 Size of nyctitheriid species in area of the M1 and M1 and inestimated weight. Tooth size of the M1 and M1 were calculated bymultiplying the averaged lengths and widths of each those teeth

published in the literature for a given nyctitheriid taxon. Estimatedweight and 95% confidence intervals for nyctitheriid species are givenin grams and calculated based on equations from Bloch et al. (1998)

M1 M1

n Tooth size (mm2) Estimated weight (g)with 95% CI

n Tooth size (mm2) Estimated weight (g)with 95% CI

Plagioctenodon krausae 9 1.75 13.95 ± 1.36 0

Plagioctenodon savagei 1 2.70* 28.30 ± 2.36 0

Plagioctenodon rosei 3 1.49 10.72 ± 1.67 4 3.60 21.74 ± 1.58

Plagioctenodon dormaalensis 18 1.16 7.17 ± 1.30 10 2.12 8.77 ± 1.38

Red Hot P. dormaalensis 1 1.06 6.20 ± 2.40 0

Plagioctenodon thewisseni 5 0.93 5.01 ± 1.54 3 1.93 7.49 ± 1.72

Leptacodon tener 3 1.31 8.71 ± 1.68 0

Leptacodon munusculum 3 1.18 7.38 ± 1.68 0

Leptacodon catulus 1 1.17 7.25 ± 2.39 0

Leptacodon packi 5 1.56 11.62 ± 1.50 1 2.57 12.20 ± 2.48

Leptacodon nascimentoi 3 0.99 5.53 ± 1.70 1 2.02 8.10 ± 2.49

Leptacodon acherontus 2 2.82 30.38 ± 1.84 0

Leptacodon donkroni 1 0.70* 3.14 ± 2.43 1 1.49 4.78 ± 2.51

Leptacodon choristus 1 3.58 44.83 ± 2.36 0

Nycitherium velox 3 1.94 16.57 ± 1.66 6 3.52 20.96 ± 1.45

Nyctitherium serotinum 10 1.60 12.08 ± 1.35 12 2.28 9.96 ± 1.34

Nyctitherium krishtalkai 5 1.19 7.48 ± 1.52 2 2.38 10.70 ± 1.91

Nyctitherium christopheri 0 1 4.08 27.01 ± 2.46

Acrodentis rosenorum 1 1.13 6.81 ± 2.40 1 2.30 10.08 ± 2.48

Ceutholestes dolosus 2 3.28 38.88 ± 1.83 0

Limaconyssus habrus 1 1.30 8.61 ± 2.39 0

Pontifactor bestiola 0 10 2.88 14.87 ± 1.35

Wyonycteris chalix 2 1.06 6.20 ± 1.88 2 2.18 9.19 ± 1.92

Wyonycteris richardi 21 1.00 5.65 ± 1.30 4 1.71 6.07 ± 1.63

Wyonycteris primitivus 1 1.52 11.14 ± 2.38 0

Wyonycteris galensis 2 2.06 18.19 ± 1.84 0

Wyonycteris microtis 0 1 1.36 4.09 ± 2.52

Plagioctenoides microlestes 1 0.83 4.11 ± 2.42 0

Amphidozotherium cayluxi 6 2.86 31.10 ± 1.42 2 2.55 12.04 ± 1.91

Saturninia gracilis 14 1.23* 7.85 ± 1.32 6 1.90 7.32 ± 1.50

Saturninia mamertensis 2 0.85* 4.34 ± 1.90 1 1.35 4.05 ± 2.52

Saturninia rigasii 1 2.05 18.03 ± 2.37 0

Saturninia ceciliensis 1 1.75* 13.94 ± 2.37 0

Saturninia pelissiei 0 1 3.43 20.04 ± 2.46

Cryptotopos carbonum 1 1.94* 16.48 ± 2.37 0

Crypototopos beatus 15 2.45* 24.17 ± 1.26 3 3.90 24.96 ± 1.69

Cryptotopos woodi 3 2.38 23.10 ± 1.65 0

Cryptotopos hartenbergi 5 1.82 14.86 ± 1.49 0

Scraeva hatherwoodensis 1 1.65 12.70 ± 2.38 0

Placentidens lotus 1 1.30 8.61 ± 2.39 1 2.80* 14.16 ± 2.47

Euronyctia montana 0 1 2.88 14.88 ± 2.47

Euronyctia grisollensis 1 1.31 8.75 ± 2.39 0

Paradoxonycteris soricodon 0 1 2.53 11.87 ± 2.48

Asionyctia guoi 16 1.18* 7.39 ± 1.31 9 2.46 11.32 ± 1.39

Bumbanius rarus 6 2.27 21.28 ± 1.43 1 5.27 41.84 ± 2.45

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elongate P3, and the large temporal range extension thatwould occur if the Y2K Quarry specimens were includ-ed in the new species causes us to refrain from addingthe Y2K Plagioctenodon to the referred specimens. Thefossils included in “Cf. Plagioctenodon krausae” andPlagioctenodon sp. consist mostly of isolated teeth andit has only been with the preparation of fresh waterlimestone that there has been sufficient fossils to diag-nose this new species of Plagioctenodon.

Bea rd and Dawson (2009) repor t ed a sma l lPlagioctenodon species from the Red Hot Local Fauna ofthe early Eocene of Mississippi and referred it toP. dormaalensis based on the morphology of an isolated M1

andM2. We estimate the mass of the Red Hot Plagioctenodonspecies to be 6.20 g based on the M1, a mass interme-diate of those for P. thewisseni and P. dormaalensis(Table 3). Although a similarly sized Plagioctenodonis now known in North America, the Plagioctenodonfrom Mississippi still appears to share closer affinitieswith P. dormaalensis. The M1 paraconid is less lingual-ly shifted and less anteriorly projecting than the condi-tion seen in P. thewisseni and all of the cusps are lessacute. The M2 of P. dormaalensis and the Red HotPlagioctenodon exhibits less expanded parastylar andmetastylar lobes and a larger hypocone situated on amore expanded postcingulum in comparison toP. thewisseni. Larger sample sizes and associated denti-tions, particularly from the Red Hot Local Fauna, arenecessary to determine if the significant morphologicaldifferences between P. thewisseni and the Red HotPlagioctenodon represent intraspecific variation. If thetaxon from the Red Hot Local Fauna is P. dormaalensis, itwould represent the only nyctitheriid species on two separatecontinents. Such a broad paleobiogeographic distribution isnot inconsistent with the hypothesis discussed below of mul-tiple dispersals of nyctitheriid clades between North Americaand Europe.

Recognition of P. thewisseni increases the late Paleocenediversity of nyctitheriids in the Clarks Fork Basin to sixspecies: P. thewisseni, P. rosei, Wyonycteris chalix,Ceutholestes dolosus, Limaconyssus habrus (Gunnell et al.2008), and an unnamed taxon alternately called cf. Pontifactor

bestiola (Rose 1981) or cf.Wyonycteris sp. (Gingerich 1987).Rose et al. (2012) noted several other sympatric occurrencesof nyctitheriids during the Paleogene, drawing a comparisonwith the overlapping geographic ranges of modern shrewspecies. Although it might be reasonable to expect someoverlap in use of resources in such a speciose, sympatricassemblage of small-bodied, insectivorous mammals, the den-tal morphologies of these six taxa are remarkably similar withno obvious evidence for niche-partitioning and, therefore,cranial and postcranial evidence may be necessary to addressthis paleoecological question.

Results

The new technology search in TNT yielded four most parsi-monious trees (MPTs) of 330 steps and the traditional searchwas unable to find any additional trees. The strict consensus(Fig. 6) contains four nodes with polytomy. The consistencyindex is 0.282 and the retention index is 0.601. The Bremersupports for all of the clades are very low (Fig. 6), which is notsurprising because of the low number of characters relative tonumber of taxa.

Results from this analysis suggest that Tiffanian“Wyonycteris” microtis shares a closer relationship withtaxa included in the outgroup, and thus does not supportits identification as a nyctitheriid. Instead, twoerinaceomorph taxa, Macrocranion junnei andAdunator minutus, are more closely related to the restof a monophyletic Nyctitheriidae. The most primitivenyctitheriids are the five included Asian taxa, consecu-tively nested in a paraphyletic clade outside the NorthAmerican and European nyctitheriids.

Among European and North American Nyctitheriidae,the results show some support of generic monophyly,including a monophyletic Plagioctenodon, consisting ofP. dormaalensis, P. rosei, P. thewisseni, P. krausae, andP. savagei. This supports the proposal by Beard andDawson (2009) to include P. dormaalensis and P. roseiin Plagioctenodon, rather than Leptacodon. Other monophy-letic genera found were Nyctitherium, Plagioctenoides,Euronyctia, and Cryptotopos, if Saturninia carbonum is

Table 3 (continued)

M1 M1

Eosoricodon terrigena 0 1 2.30 10.07 ± 2.48

Oedolius perexiguus 10 1.11 6.64 ± 1.38 0

Edzenius lus 2 1.31 8.68 ± 1.87 0

n number of specimens used in the calculations

*denotes values that were calculated using a specimen either with an estimated length or width

J Mammal Evol

subsumed into the latter and classified as Cryptotoposcarbonum. The Wyonycteris clade is represented asparaphyletic with respect to Pontifactor bestiola. Thetwo most diverse genera, Leptacodon (eight species)and Saturninia (nine species), are both likely polyphy-letic as currently classified, with most of their species

widely separated from the type species L. tener andS. gracilis.

Although there does seem to be a geographic signalin the data (Fig. 7), separating the Asian nyctitheriids atthe base of the tree, the European nyctitheriids in a deeplynested clade, and the North American nyctitheriids between

Fig. 7 Strict consensus of the phylogenetic analysis of Nyctitheriidaewith stratigraphic and biogeographic information. The dark gray and lightgray boxes denote Asian and European taxa, respectively, and non-shaded taxa are North American. Stratigraphic ranges are either in blackor are striped. The European ranges could only be constrained to MPlevel, except in the case of the two taxa from Dormaal, which are thoughtto be earliest Eocene and coincide with the PETM (e.g., Smith and Smith

1996). The diagonally striped stratigraphic ranges represent a locality orformation with a highly uncertain age. The vertically striped stratigraphicranges represent uncertain identifications of taxa outside of their knownranges. The medium gray vertical lines represent, from left to right, theCretaceous-Paleogene boundary, the Paleocene-Eocene ThermalMaximum, and the Grande Coupure or Eocene-Oligocene Boundary(Woodburne 2004)

J Mammal Evol

the two groups, there appears to be some intermixing betweenthe European and North American taxa. Several early andmiddle European taxa are found in predominantlyNorth American clades, including Saturninia ceciliensis,Lep tacodon nasc imen to i , Placen t idens lo tus ,Plagioctenodon dormaalensis, and Wyonycteris richardi.A single North American nyctitheriid, Limaconyssushabrus, is found in the clade including all late EoceneEuropean taxa. These results suggest that there wasconsiderable interchange between the nyctitheriid taxaof Europe and North America.

Discussion

Outgroup

Our results suggest that “Wyonycteris” microtis is best classi-fied outside of Nyctitheriidae. “Wyonycteris” microtis is themost basal taxon of the ingroup. Sister to “W.” microtis is agroup consisting of two taxa traditionally classified aserinaceomorphs and Nyctitheriidae (Node A in Fig. 6), whichis distinguished by the presence of a hypocone and the loss ofa stylocone on the upper molars (See Appendix 2 for a list of

Fig. 7 (continued)

J Mammal Evol

all unambiguous synapomorphies at key nodes). The basalposition of “W.” microtis might be driven in part by theabsence of hypocones and pericones on the upper molars.Although these features are apparently absent on the typespecimen, it is at least possible that a hypocone and periconecould have been present on less damaged or worn specimens(Secord 2008; Beard and Dawson 2009). Regardless, therelatively long upper molar shape, presence of small pre-and postcingula, and the presence of a stylocone on M1 of“W.” microtis support its basal position in the cladogram.Given the current state of knowledge for this taxon, knownonly from a single specimen preserving M1–3, claims regard-ing the interfamilial relationships of this taxon should beviewed as tenuous at best.

Also in the outgroup relative to Nyctitheriidae, Adunatorminutus and Macrocranion junnei were recovered as sistertaxa (Node B) representing Erinaceomorpha (e.g.,Novacek et al. 1985; although see Hooker and Russell2012). The two taxa share several characteristics of thatclade including relatively wider talonids than trigonidson the lower molars and relatively reduced parastylarlobes on the upper molars.

Asian Nyctitheriidae

Results suggest that the five taxa from Asia included in theanalysis are consecutively nested at the base of theNyctitheriidae, with the three basal-most taxa, Edzenius lus,Oedolius perexiguus, and Asionyctia guoi, consistent with aparaphyletic subfamily Asionyctiinae (between Nodes C andD). Asionyctiinae was first proposed by Missiaen and Smith(2005) to include the genera Asionyctia, Bumbanius,Oedolius, Voltaia, and Bayanulanius, but was later modifiedby Lopatin (2006) to not include Bumbanius. Although thissubfamily is said to be distinguished in part by apremolariform P4 with a small to absent metaconid and highlytransverse upper molars (Missiaen and Smith 2005; Lopatin2006), these are also characters seen in primitive eutherians,including the outgroup taxon Maelestes gobiensis.Synapomorphies uniting Bumbanius rarus with the rest ofNyctitheriidae to the exclusion of the basal Asionyctiinae(Node D) include the presence of a metaconid on the P4 anda reduction in the upper molar length to width ratio.Bumbanius has been classified in the subfamily Praolestinaewith Praolestes (not included in this study) and Eosoricodonterrigena is classified in the monospecific subfamilyEosoricodontinae (Lopatin 2006). Our results suggest thatthose subfamilies might be nested consecutively within“Asionyctiinae” and outside the clade consisting of the restof the North American and European nyctitheriids, butthis result could be further tested with inclusion of otherAsian taxa in the analysis, which is beyond the scope ofthe current study.

Asian nyctitheriids have previously been classified as asingle, monophyletic subfamily likely derived from a “prim-itive Leptacodon-like” morphology (Missiaen and Smith2005: 520). One of the most significant changes from thepresumed primitive condition to the Asionyctiinae was thereduction of the P4 from semimolariform to premolariform,with the losses of the talonid basin, two talonid cusps, and themetaconid. A premolariform P4 is also present in many earlyeutherians, but it was argued that in the Asionyctiinae, it wassecondarily derived (Missiaen and Smith 2005). With therecognition of greater diversity in the Asian nyctitheriids andthe addition of two more Asian subfamilies, Lopatin (2006)challenged the monophyly of Asian nyctitheriids, but stillconsidered the subfamily including Leptacodon, theNyctitheriinae, to be closest to the primitive condition in thefamily. This position is supported by stratigraphic evidence.The oldest purported nyctitheriid, known from a single P4(Van Valen 1978), is from the Puercan NALMA from NorthAmerica. By the Torrejonian NALMA, the first definitivenyctitheriids L. tener and L. munusculum appear, and by theearly Tiffanian NALMA, a modest diversity is present withL. packi, L. acherontus, and L. choristus making their firstappearances (Gunnell et al. 2008). In contrast, Asiannyctitheriids do not appear until the Gashatan ALMA,the beginning of which is concurrent with the TiffanianNALMA (Ti5a; Missiaen 2011). Thus, nyctitheriids ap-pear in North America 3–7 million years before they doin Asia. The conflicting stratigraphic and cladistic evi-dence suggests two possibilities: 1) the cladistic resultsare reflecting a hidden diversity of early PaleoceneAsian nyctitheriids not yet recovered from the fossilrecord, or 2) Asian nyctitheriids originated from aLeptacodon-like morphology, later migrating fromNorth America to Asia, and their primitive-looking char-acters are actually secondarily derived. Paleontologicalinvestigations of the early Paleocene in Asia, together with acladistic analysis with a more exhaustive taxonomic treatmentof Asian nyctitheriids have the potential to provide substantialinsight into this issue.

North American and European Nyctitheriidae

Several characteristics differentiate North American andEuropean nyctitheriids from those recovered from Asia(Node E). These include semi-molarization of P4, pos-sibly derived from the more premolariform state foundin Asionyctiinae, specifically in having a basined talonidand more than one talonid cusp. The lower molartalonids are also notably different: the talonid basin iswider so that it is subequal to the trigonid width, thehypoconulid is shifted to occupy a position on themidline, and the entoconid is subequal in height to the

J Mammal Evol

hypoconid in contrast to its smaller and lower positionin most Asian taxa.

Monophyly of the North American and Europeansubfamilies, Nyctitheriinae and Amphidozotheriinae, is notsupported by this study. According to McKenna and Bell(1997) and modified by Hooker and Weidmann (2000), theAmphidozotheriinae includes Amphidozotherium ,Paradoxonycteris, Euronyctia, Plagioctenoides, and theOligoceneDarbonetus (not included in this cladistic analysis).The former three taxa are nested deeply within a late EoceneEuropean clade (Node S) with proposed nyctitheriinesSaturninia rigasii and Scraeva hatherwoodensis and the un-classified Limaconyssus habrus. The group represented byNode S is sister to Node O, which includes two NorthAmerican clades. The first represents the sole NorthAmerican genus classified as an amphidozotheriine,Plagioctenoides (Node P), and the second is a clade thatincludes Wyonycteris and Pontifactor (Node Q).

These results of this analysis strongly suggest thatLeptacodon and Saturninia, as they are currently understood,are not monophyletic. Although these genera have been mod-ified over the years, it is apparent that several species stillclassified with them, likely due to a lack of distinguishingderived features, should be reconsidered. Furthermore, thetype species of Leptacodon, L. tener, is far removed fromthe other “Leptacodon” species, with some uncertainty as tothe specific relationships of that taxon. In the strict consensusit is part of a polytomy (Node G) with two large clades (NodesH and K) and in the four MPTs, it falls out as either the sistertaxon to a clade including both Nodes H and K or as sisteronly to Node K, the clade comprised of L. acherontus and alltaxa nested more deeply. Beard and Dawson (2009) suggestedthat Leptacodon is a relatively primitive Paleocene clade thatincludes L. tener, L. packi, and L. munusculum. Several mor-phological steps separate these taxa, but a particularly signif-icant character separates L. tener from L. packi ,L. munusculum, and other basal nyctitheriids: the presenceof a metacone on P4. In taxa with the relevant tooth availablefor study, this cusp is absent in all basal nyctitheriids andpresent in all nyctitheriids at Node G and more highly nested.Therefore, we propose that at least five of the Leptacodonspecies merit reattribution to a new or different genus:L. donkroni, L. munusculum, L. nascimentoi, L. choristus,and L. packi. Most likely L. proserpinae, upon discovery ofadditional fossils, might also merit reattribution.Unfortunately this study faces the same problems that authorsin the past had in that there are few, if any, goodderived characters grouping these taxa. For that reason,we do not rename any of these taxa or create newclades. Some authors have suggested synonymizingsome of the Leptacodon species with other nyctitheriidgenera. Krishtalka (1976) suggested that L. packi maybe synonymized with Nyctitherium, but Bown and

Schankler (1982) instead hypothesized that it showsrelatively primitive, generalized morphology for earlysoricomorphs. Our phylogenetic analysis supports thelatter theory. Krishtalka (1976) further suggested thatL. munusculum may best be classif ied withinPontifactor, but our results do not support this hypoth-esis, either.

Results from the cladistic analysis also strongly suggestthat species currently classified in Saturninia are polyphyleticwith respect to each other. Among these, S. ceciliensis is themost problematic, falling out with the more primitiveLeptacodon species and far removed from the otherSaturninia species. Although it was mentioned thatS. ceciliensis has some significant differences from otherSaturninia species, such as lower molars with a labial termi-nation of the cristid obliqua and a shorter entoconid thanhypoconid (Storch and Haubold 1989), the extremely basalposition it occupies in the cladogram seems incongruous withits temporal distribution. Saturninia ceciliensis is thestratigraphically oldest Saturninia species, but its middleEocene age is still much younger than the PaleoceneL. munusculum and earliest Eocene L. donkroni that itshares a clade with. It is only known from one speci-men consisting of lower teeth, however, and thereforemany of the distinguishing characters for the laterEocene European nyctitheriids, particularly the expandedpostcingular shelves of the P4 and upper molars, cannotbe assessed. The other Saturninia taxa are paraphyleticwith the type species S. gracilis in a clade of mostlylate Eocene European taxa, but other than possiblyS. mamertensis, they should probably be reassigned toa different genus. Similar to the situation withLeptacodon, many taxa were placed in Saturninia basedon a very broad diagnosis of the group (Sigé 1976).Some taxa were subsequently removed from the genusand placed in morphologically distinct genera (Sigé1997; Hooker and Weidmann 2000), but that has result-ed in Saturninia being defined by an amalgamation ofcharacters present in the remaining species, rather thanby unique, derived traits.

The strict consensus shows a clade including Leptacodoncatulus, Placentidens lotus, Ceutholestes dolosus, Acrodentisrosenorum, and all of the Nyctitherium species (Node H),united by having a relatively wide P4, a longer M1 than M2,lower molars with a cristid obliqua terminating linguallyon the protocristid, and a postcingulid on the lowermolars. Within that clade, European P. lotus falls outas sister taxon to North American C. dolosus (Node I),a result foreshadowed by Rose and Gingerich (1987)who noted the similarities between the two taxa. Atthe time, Placentidens was thought to be a plagiomenidand Ceutholestes was described as an insectivore withuncertain affinities, but it was noted that the two shared

J Mammal Evol

lingually canted, exodaenodont molars with acute cusps(Rose and Gingerich 1987). It has also been observedthat the morphology of P. lotus is very similar to that ofWyonycteris (Gingerich 1987; Hand et al. 1994; Beardand Dawson 2009). Smith (1995) suggested thatWyonycteris is closely related to Pontifactor andRemiculus, but argued against a close relationship withPlacentidens. Beard and Dawson (2009) proposed thesubfami ly Placen t inae , a c lade cons i s t ing ofPlacentidens, Remiculus, Wyonycteris, and Pontifactor.The inclusion of Placentidens in that clade was basedon the more basal morphology of Wyonycteris primitivusacting as an intermediate between Placentidens and themore derived Wyonycteris species. Our analysis does notsupport a close relationship of Placentidens withWyonycteris or Pontifactor, although a close relationshipbetween Wyonycteris and Pontifactor is supported (NodeQ). Remiculus was not included in this clade because itis likely an adapisoriculid (Gheerbrant and Russell1989; de Bast et al. 2012).

The synapomorphies uniting Ceutholestes dolosus andPlacentidens lotus (Node I) are the presence of a metaconidon the P3 and lower molars with a greater talonid widthcompared to that of the trigonid, a larger metaconid thanprotoconid, and significantly taller entoconids thanhypoconids. The synapomorphies concerning the lowermolars are present in various nyctitheriid taxa throughout thecladogram, but the P3 metaconid is unique toCeutholestes andPlacentidens. There is a possibility that the isolated toothidentified as the P3 of P. lotus is actually the P4; Russellet al. (1973) hypothesized that Placentidens was a primitiveplagiomenid and their allocation of the tooth to the P3 positionwas based on comparisons to plagiomenid premolars thatexhibit a much more highly molariform P4. If Placentidensis a nyctitheriid, the P3 identification is much less certainbecause some nyctitheriids have a premolariform P4.Although we don’t feel we can confidently ascribe the toothin question to either the P3 or P4 position, we did test whetherthe phylogenetic placement of P. lotus changes dependent onthe tooth position. When the tooth was coded as a P4 ratherthan a P3, the topology of the strict consensus tree didnot change, but the MPTs did increase in length bythree steps. One of the most distinguishing features ofCeutholestes is that it has a fully molariform P4, where-as other insectivorans and nyctitheriids do not (Roseand Gingerich 1987). If the “P3” of Placentidens istruly a P3, the more molariform characters it share withCeutholestes, such as the acquisition of a metaconid,suggests that the unknown Placentidens P4 may alsobe fully molariform and provide further synapomorphiesfor the two taxa.

Sister to Placentidens lotus + Ceutholestes dolosus is amonophyletic clade comprised of Acrodentis rosenorum and

all Nyctitherium species. Acrodentis is in a sister relationshipwith Nyctitherium and Nyctitherium krishtalkai is found to bethe most primitiveNyctitherium species. This echoes the resultfound in a recent analysis that tested the relationship ofNyctitherium to other North American nyctitheriids(Christiansen and Stucky 2013). We were unable to determinethe phylogenetic relationship between Nyctitheriumchristopheri, Nyctitherium serotinum, and Nyctitheriumve lox because a d i r e c t compa r i son be tweenN. christopheri and N. serotinum was not possible forthis analysis; there are no lower teeth known forN. christopheri and the upper teeth of N. serotinum have notbeen described or figured in the literature.

Plagioctenodon (sensu Beard and Dawson 2009, plusP. thewisseni) is found to be a monophyletic clade. Beardand Dawson’s (2009) proposed synapomorphies for the ge-nus, however, (an anteriorly canted, relatively small P3 and amore molariform P4 trigonid with a relatively high paraconid)appear to have accumulated gradually in the evolutionaryhistory of Nyctitheriidae. Although the relatively high P4paraconid appears as a synapomorphy for the genus, thedistinguishing P3 characters evolved earlier in the tree. Theanterior cant of the P3 protoconid first appears at Node K andis seen in Leptacodon acherontus and many of the moredeeply nested taxa in that clade. The reduction in size of theP3 relative to the surrounding molars is a synapomorphyfor Node L and is present in all of the taxa that makeup that clade with the relevant morphology known,including species in Plagioctenodon, Plagioctenoides,Wyonycteris, and the late Eocene European nyctitheriids.A l t hough th i s P 3 mo rpho logy i s p r e s en t i nPlagioctenodon, it should be recognized that those char-acters are gained at an earlier stage in nyctitheriidevolution and that definitive diagnoses for the genusshould be based on the combination of the P3 charac-terist ics with the P4 paraconid height. WithinPlagioctenodon, the North American taxa are separatedfrom the basalmost European species, P. dormaalensis,by having taller entoconids than hypoconids on thelower molars. The most nested species, P. krausae andP. savagei, are also the youngest species and are differ-entiated from the older species by having the entoconidpositioned on the posterolingual margin of the tooth,rather than being anterolingual to the hypoconulid, acharacter formerly included in the generic diagnosis(Bown and Schankler 1982). The position of the soleEuropean Plagioctenodon species at the base of theclade suggests that the genus may have originated inEurope and then later migrated to North America. Thefact that P. dormaalensis is from the earliest Eocene andtherefore younger than the more nested late Paleocenetaxa, P. rosei and P. thewisseni, suggests that olderPlagioctenodon might have been present outside of

J Mammal Evol

North America. Alternatively, but not supported by ourresults, P. dormaalensis might have evolved from one ofthe earlier species in North America and, after migrat-ing, diverged sufficiently in morphology from the restof the genus (“re-evolving” primitive morphology) toappear more basal in this cladogram. A NorthAmerican origin is further supported by the greaterdiversity of Plagioctenodon in North America, suggest-ing the family arose on that continent and a singlemember later migrated to Europe.

Node N includes all species classified in Plagioctenoides,Wyonycteris, and Pontifactor, as well as the late EoceneEuropean nyctitheriids, in which a single Paleocene NorthAmerican nyctitheriid, Limaconyssus habrus, is deeply em-bedded. Synapomorphies supporting Node N are a crestiformparaconid on the lower molar, a cristid obliqua ascending theprotocristid to end high on the metaconid on the lower molar,and a precingulum containing a pericone on the upper molar.The crestiform paraconid is a character that is present in thebasalmost nyctitheriids, including all of the Asian taxa and thebasalmost clade of European and North American taxa thatincludes Saturninia ceciliensis, Leptacodon munusculum, andLeptacodon donkroni. In most other nyctitheriids theparaconid is cuspate, but at Node N the crestiform statereoccurs and is present in Plagioctenoides, Wyonycterisprimitivus, some species of Saturninia, Paradoxonycteris,and Euronyctia. This character seems to have evolved andreversed at least twice in the family’s history. Thetermination of the cristid obliqua high on the metaconidof the lower molar and the pericone on the upper molarhave also occurred several times in the family’s history.In fact, there are many hypotheses of reversals through-out the cladogram, likely playing a strong role in thedifficulty in determining intrafamilial nyctitheriid rela-tionships over the last century.

A monophyletic group that includes Wyonycteris,Pontifactor, and Plagioctenoides is present (Node O), inwhich Wyonycteris is paraphyletic in a clade withPontifactor. A monophyletic Plagioctenoides is sister to theparaphyleticWyonycteris. Node O has five unambiguous syn-apomorphies, one of which, nyctalodonty, is only present inthis clade. A nyctalodont condition refers to the relationshipbetween the lower molar talonid cusps, in which thehypoconid and hypoconulid are connected by a crest, whilethere is a fissure between the hypoconulid and entoconid(Menu and Sigé 1971). This clade also has two significantcharacteristics that are rare within the rest of Nyctitheriidae: amesostyle and dilambdodonty in the upper molars. These twocharacter states do not show up as unambiguous synapomor-phies at Node O because Plagioctenoides does not have anyupper teeth attributed at the species level and therefore thetiming at which these characters evolved is uncertain.Although upper molars have been described attributed to the

genus (Rose et al. 2012) that have both a mesostyle and thedilambdodont condition, they were not included in the phylo-genetic analysis because of specific uncertainty. That said, ifthey belong to either Plagioctenoides species, they couldsupport the acquisition of the two character states at NodeO. In nyctitheriids, a mesostyle is only present inWyonycterisspecies excluding Wyonycteris primitivus, Pontifactor,Plagioctenoides sp., Nyctitherium velox, and the questionablyattributed “Wyonycteris” microtis and dilambdodonty is onlyfound in Wyonycteris species excluding W. primitivus,Pontifactor, Plagioctenoides sp., Paradoxonycteris, andEuronyctia.

Close relationships of Plagioctenoides, Wyonycteris, andPontifactor were predicted by previous authors (Gingerich1987; Smith 1995; Rose et al. 2012). In the initial descriptionof the first Wyonycteris species, Gingerich (1987) noted sim-ilarities between it and Pontifactor, but concluded that thedifferences between the two taxa were great enough to meritgeneric level distinction. Our results support these conclusionsby finding Pontifactor bestiola within a paraphyleticWyonycteris, but P. bestiola has four autapomorphies in theupper molars differentiating it from Wyonycteris: lack ofpericone, more labially situated conules, subequal heights ofthe paracone and metacone, and an expanded postcingulum.Concerning Wyonycteris and Plagioctenoides, Rose et al.(2012) noted that the similarities were so great between thetwo genera that theymay not be generically distinct. Our studydoes show a separation of the two, but it is only supported by asingle synapomorphy for each genus. The synapomorphy forPlagioctenoides is a single prominent cusp on the P4 talonid(Rose et al. 2012), whereas the Wyonycteris species with aknown P4 have three minute cusps (e.g., Gingerich 1987) andthe synapomorphy forWyonycteris is a more anteroposteriorlycompressed trigonid on the lower molar than is seen inPlagioctenoides. Although it seems questionable to separategenera based on such small morphological differences, wehesitate to combine the two when our analysis does show aclear separation of two monophyletic groups.

WithinWyonycteris (Node Q),W. primitivus is found to beat the base, in accordance with Beard and Dawson (2009).Many of the characteristics used to differentiate Wyonycterisin its original description, such as a twinned metaconid on thelower molar, a mesostyle, and dilambdodonty (Gingerich1987) are actually found at node R, nested withinW. primitivus. Beard and Dawson (2009) based their genericattribution of W. primitivus on other morphological similari-ties, particularly the nyctalodont talonids, and hypothesizedthat the lack of mesostyle and dilambdodonty inW. primitivuswas due to its status as a basal species of the genus, which thisstudy corroborates.

The clade of late Eocene European nyctitheriids (Node S) ismarked by an expansion of the postcingulum on the P4 andupper molars into a large shelf; this is seen throughout the

J Mammal Evol

entire clade in the taxa with known upper teeth. In thenyctitheriids outside of Node S, expanded postcingula on theupper molars only occur in the terminal genera Nyctitheriumand Pontifactor. This suggests that expanded postcingulaevolved three times within Nyctitheriidae and that it is a fairlystable character once acquired, as no lineages show the sec-ondary loss of the character. There are two possible nodesrepresenting a monophyletic Cryptotopos: Node T or NodeU. Since Cryptotopos was first described (Crochet 1974), itsstatus as a genus and the species that are classified within ithave been in flux. Sigé (1976) synonymized CryptotoposwithSaturninia and renamed the type species ofCryptotopos beatusto Saturninia beata. Hooker andWeidmann (2000) resurrectedthe genus and reallocated several species to it: C. beatus,C. woodi, C. hartenbergi, and potentially Saturninia pirenaicaand Saturninia pelissiei. Ziegler (2007) added a newOligocenespecies, Cryptotopos communis, to the genus and also sug-gested that Saturninia carbonummay best be classified withinCryptotopos, as well. This analysis supports the allocation ofS. carbonum to Cryptotopos because that species is deeplynested within the other Cryptotopos species. Node U includesC. beatus, C. woodi, C. hartenbergi, and the newly allocatedCryptotopos carbonum. It is supported by three synapomor-phies: an anteroposteriorly compressed lower molar trigonid, acristid obliqua on the lower molars whose distal portion isconvex occlusally, and an absent to weak centrocrista on theupper molars. Of these characters, the first two traits have beenused in the diagnosis of Cryptotopos (Hooker and Weidmann2000; Ziegler 2007). In a broader sense of the genus, Node Tcould represent Cryptotopos; this expanded clade would in-clude the previously suggested Cryptotopos speciesS. pelissiei, and also Saturninia intermedia. The three synapo-morphies for Node T are a relatively wide P4, a cuspateparaconid on the lower molars, and a notch located halfwaydown the cristid obliqua on the lower molars. Of these, only thelast character has been used to diagnose the genus (Hooker andWeidmann 2000; Ziegler 2007). This indicates that the diag-nostic characters for Cryptotopos are accumulated gradually inthe clade and that the species classified in the genus differdepending on which characters are used for diagnosis.Saturninia pirenaica, the only other species suggested to beclassified in Cryptotopos, is part of a polytomy at Node S.Although its classification as a species of Cryptotopos is notsupported, it should be noted that few characters could becoded for S. pirenaica because it is not well known and onlya few figures exist in the literature (Gibert Clols and AgustíBallester 1979; Sigé 1997).

A monophyletic Euronyctia as sister to Paradoxonycterisis supported at Node X. This is in agreement with the view inHooker and Weidmann (2000) that the two genera are almostindistinguishable. The clade including both genera showsanother acquisition of dilambdodonty in the upper molars,but unlike the Wyonycteris taxa associated with Node R,

Euronyctia and Paradoxonycteris do not have a mesoconidor nyctalodont lower molar talonids. The only differencebetween Euronyctia and Paradoxonycteris in this analysis isthat Euronyctia has a more lingually situated hypoconulid.Smith (2004) argued that the holotype of Paradoxonycterissoricodon is sufficiently damaged for that taxon to be consid-ered a nomen nudum or dubium and that only Euronyctiais a valid genus. The holotype of Paradoxonycteris (asillustrated by Hooker and Weidmann [2000]) seemed com-plete enough to be coded into the analysis and it wastherefore retained as a distinct species, but it may beadvisable to synonymize Paradoxonycteris andEuronyctia. A revision of these genera, however, is be-yond the scope of this study.

A clade including Amphidozotherium cayluxi, Saturniniarigasii, Scraeva hatherwoodensis, and Limaconyssus habrus(Node Y) is supported by having lower molars with narrowertalonids than trigonids, a cuspate paraconid, and a largerparaconid than metaconid. Our results suggest that the relativelynarrow talonids of this clade might represent a character reversal,as this is the state also seen in the Asian nyctitheriids.Within thisclade, Scraeva and Limaconyssus are sister taxa (Node Z) withthe following synapomorphies: a large, cuspate paraconid on theP4 and lower molars with a trigonid at least twice as high as thetalonid. The former character state is also seen in the basalmostnyctitheriids, whereas the latter is the state seen in the outgrouptaxon Maelestes, suggesting two more examples of likely char-acter reversals. The placement of L. habrus in this tree is suspect,however, because it is the only North American taxa withinNode S, it is only known from lower teeth, whichmeans the presence of important synapomorphies forNode S such as the expansion of the postcingular shelfon the P4 and upper molars cannot be assessed, and itslate Paleocene age is more than ten million years olderthan the late Eocene age of the other taxa in the clade.Thus, it is possible, although not supported by ourcladistic results, that Limaconyssus and the late Eocenenyctitheriids may have independently regained someprimitive characteristics that, combined with an assort-ment of derived traits, caused the strange placement ofLimaconyssus as a highly nested taxon in a late EoceneEuropean clade.

Biogeography of Nyctitheriidae

Nyctitheriidae is roughly grouped into three major clades thatcorrespond to three separate continents (Fig. 7). The fiveAsian species in the analysis are consecutively nested at thebase of the tree in a paraphyletic relationship. Although thereare several more Asian nyctitheriids not included in our study(see Lopatin 2006), species from all three Asian subfamilieswere included in an attempt to capture much of the morpho-logical disparity on the continent. Because of this, the position

J Mammal Evol

of the Asian nyctitheriids outside of the European and NorthAmerican clades, is likely to be a true pattern, even if thespecific relationships of the Asian taxa are less certain. Resultsfrom the analysis support an Asian origin for the family withdispersal into North America by at least the Torrejonian andpossibly the Puercan. But as was noted in the discus-sion of the phylogenetic results, the temporal data con-flict with the cladistic results, in that the oldestnyctitheriids are North American. This conflicting evi-dence can be reconciled in the future either by thediscovery of early Paleocene Asian nyctitheriids orthrough a more exhaustive test of character polarity in theAsian taxa demonstrating that the “primitive” traits in thosetaxa are actually character reversals following dispersal andisolation on the Asian continent. Regardless, the monophylyof the European and North American nyctitheriids, to theexclusion of the Asian taxa, would seem to indicate thatthere was no dispersal of nyctitheriids to or from Asia afterthe early Paleocene. Russell and Dashzeveg (1986) noted thesimilarities of early Eocene Asian nyctitheriids and otherinsectivores to late Paleocene forms in North America andsuggested that the Asian taxa were not strongly endemic, butMissiaen and Smith (2005) proposed a single migration eventbetween North America and Asia in the late Paleocene, afterwhich the Asian nyctitheriids evolved in isolation. The resultsof this analysis better support the idea of a single migrationevent, whether it is from Asia to North America in the earlyPaleocene or from North America to Asia in Ti-5a, but moreAsian nyctitheriids should be included in the phylogeneticanalysis before this can be said definitively.

All of the NorthAmerican and European taxa (only excludingthose that were latest Eocene and strictly Oligocene) were in-cluded in this analysis, which gives us a more confidant view ofthe patterns seen between those two continents. The earliestnyctitheriids are found in the Paleocene of North America inthe form of several species classified as Leptacodon (found to bepolyphyletic here). By the late Paleocene the family is relativelydiverse, with the presence of Ceutholestes, Limaconyssus, andrepresentatives of Plagioctenodon and Wyonycteris. There ap-pears to have been a large dispersal event between NorthAmerica and Europe around the Paleocene-Eocene Boundary,when the stratigraphically earliest European nyctitheriids appearin four morphologically distinct clades. These species,Leptacodon nascimentoi, Placentidens lotus, Plagioctenodondormaalensis, andWyonycteris richardi all appear in the earliestEocene, which suggests immigration in multiple clades at thistime. There is also evidence for dispersal betweenNorthAmericaand Europe at the Paleocene-Eocene boundary in other mamma-lian genera, including a proposed North America to Europe routefor Palaeonictis (Chester et al. 2010) and Europe to NorthAmerica routes for both Teilhardina (Rose et al. 2011) andMacrocranion (Smith et al. 2002). This coincides with theHolarctic dispersal events in many other clades near the

Paleocene-Eocene boundary, including hyaenodontid creodonts(Gingerich and Deutsch 1989), as well as the modern orders ofprimates, artiodactyls, and perissodactyls (Gingerich 2006;Smith et al. 2006). Although the dispersal of these groupsincluded an Asian component—and possible origination on thatcontinent (Krause and Maas 1990; Beard and Dawson 1999;Bowen et al. 2002)—we do not see evidence for a secondinstance of migration either to or fromAsia in the Nyctitheriidae.

The North American nyctitheriids as a group areparaphyletic with respect to the Eocene European taxa thatare spread throughout it. With the exception of someNyctitherium species and Pontifactor bestiola, the stratigraph-ic ranges of North American Nyctitheriidae do not extend pastthe early Eocene. A diverse clade of late Eocene nyctitheriidscan be found in Europe, but their specific origins are unclear.The cladistic results suggest that this group evolved from acommon ancestor it shares with its sister clade (comprised ofPlagioctenoides,Wyonycteris, and Pontifactor), diversified inEurope, and experienced a single migration event to NorthAmerica by the deeply nested Limaconyssus habrus. A latePaleocene timing of all of these events is required with theinclusion of L. habrus in the clade, but as was discussed in thephylogenetic results section, several phylogeneticallyinformative characters for late Eocene Europeannyctitheriids could not be coded for this taxon. If L. habrusis not included in the late Eocene European clade, the ghostlineage for that clade would be nearly 20 million years, withdiversification not occurring until the late Eocene. It istherefore possible that the late Eocene nyctitheriids mayhave arisen from one of the earlier Eocene European taxa orfrom a middle Eocene North American taxon after a laterimmigration event from North America, but with greatenough divergence that it is not being captured in thecladistic analysis. Potentially the discovery of moreSaturninia ceciliensis fossils, particularly the upper molars,may transfer this taxon to the late Eocene group and wouldrepresent a transitional middle Eocene European taxon. It alsoseems significant that one of the uniting features of all lateEocene European nyctitheriids, the expanded postcingulumon the upper molars, is also present in the middle EoceneP. bestiola, a member of the sister clade to the late EoceneEuropean clade. Smith (1996) suggests that some nyctitheriidfossils from the early Eocene of Europe are likely to bePontifactor or Wyonycteris; he notes two P4s, attributed tocf. Leptacodon (RI 218 from Rians, Sparnacian, Provence,France) by Godinot (1981) and to Saturninia sp. orLeptacodon sp. (FDN 1401 from Fordones, middle Ilerdien,Bas-Languedoc, France) by Marandat (1991), as being verysimilar in morphology to Pontifactor and a lower molar (RI382 from Rians) attributed to cf. Leptacodon by Godinot(1981) with a nyctalodont condition that would ally it withWyonycteris. Although these teeth have not been formallydiagnosed, it is possible that they are part of the ancestral

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stock of the late Eocene European clade because of their earlyEocene presence in Europe and their similar morphology tothe sister clade of late Eocene nyctitheriids. It is apparent thatseveral clades of nyctitheriids dispersed between NorthAmerica and Europe in the earliest Eocene and that theremay have been at least one further immigration event intoEurope later in the Eocene from a Pontifactor-likenyctitheriid.

Conclusions

The Nyctitheriidae is a diverse and disparate fossil family thatspanned the early Paleocene through early Oligocene and inthe early Eocene, could be found on three different continents.The stratigraphically earliest nyctitheriids are found in NorthAmerica, and the family later appeared in Asia in the latePaleocene and in Europe in the earliest Eocene. By the lateEocene, the family was solely found in Europe and thenbecame extinct in the early Oligocene. Nyctitheriidae containsover twenty genera, but two of the most diverse, Saturniniaand Leptacodon, are almost certainly polyphyletic and need tobe revised. The monophyly of other multi-species genera aresupported by our cladistic analysis, including Nyctitherium,Plagioctenodon, Plagioctenoides, Cryptotopos, andEuronyctia, whereas Wyonycteris is found to be paraphyleticwith Pontifactor. The new species of Plagioctenodon,P. thewisseni, is found to be in a clade with P. dormaalensis,P. rosei, P. krausae, and P. savagei, but the previously sug-gested synapomorphies for Plagioctenodon in the anteriorlycanted P3 protoconid and reduction in size of the P3 aregradually accumulated in the nodes nested below the genus.Only the high position of the paraconid on the P4 is found to bea synapomorphy at the Plagioctenodon node. The monophylyof the subfamilies Nyctitheriinae and Amphidozotheriinae isnot supported and these subdivisions may need to be aban-doned. The Asian nyctitheriids are found to be consecutivelynested at the base of Nyctitheriidae due to manymorphologicalsimilarities with the outgroup, but it is unlikely that the familyactually originated in Asia because nyctitheriid species arefound much earlier in North America. Instead, the position ofthe Asian taxa in the cladogram could be explained by a singleimmigration event from North America to Asia in the latePaleocene, and then isolation of the Asian nyctitheriids withconvergence upon the primitive condition in some characters.Within the North American and European taxa, there is adispersal event at the earliest Eocene that includes at least fourclades and coincides with Holarctic dispersal events of severalother mammalian clades, including hyaenodontid creodonts,Primates, Artiodactyla, and Perissodactyla.

This is the most complete phylogenetic analysis of thefamily to date and although the position of some of the taxa

and clades are likely to change upon addition of more taxa andcharacters or discovery of more fossils for already includedtaxa, many of the phylogenetic relationships suggested in theliterature (e.g., Wyonycteris + Pontifactor [Gingerich 1987];Placentidens lotus + Ceutholestes dolosus [Rose andGingerich 1987]; Euronyctia + Paradoxonycteris and reas-sessment of Cryptotopos [Hooker and Weidmann 2000]; fur-ther reassessment of Cryptotopos [Ziegler 2007]; reassess-ment of Plagioctenodon [Beard and Dawson 2009];Plagioctenoides + Wyonycteris [Rose et al. 2012];Acrodentis + Nyctitherium [Christiansen and Stucky 2013])are corroborated by this analysis and it can be used as a goodapproximation of the intrafamilial relationships as they arecurrently understood. The intrafamilial relationships ofNyctitheriidae are complex, with the evolution and reversalof many characters multiple times, but it is necessary tounderstand the phylogeny within the family before we canunderstand the relationships of the family to higher level taxawith confidence.

Acknowledgments We thank Richard Hulbert, Kristen MacKenzie,and Jason Bourque (UF) for help in cataloguing and preparation of theUF specimens. We thank Philip Gingerich (UM) and Gregg Gunnell(now of Duke Lemur Center) for access to specimens and comparativecasts and for help with loans at UM, as well as William Sanders (UM) forhelp with preparation of specimens. We thank Peter Houde (NewMexicoState University) for access to limestones containing invaluable fossils.We thank Stephen Chester (now of Brooklyn College) and Josh VanHouten (Department of Internal Medicine, Yale University) for micro-CT imaging done at the Yale University Core Center for MusculoskeletalDisorders microCT facility; and Doug Boyer, Jimmy Thostenson, andJudit Marigo (Duke University) for access to and assistance with themicroCT facilities at the Shared Materials Instrumentation Facility atDuke University. We thank Jason Bourque, Stephen Chester, Jerry Hook-er, Paul Morse, Ken Rose, and Aaron Wood for helpful discussions. Wethank John Wible and an anonymous reviewer for providing helpfulcomments that improved the manuscript. Research was in part fundedby the Miss Lucy Dickinson Fellowship, the Geological Sciences Grad-uate Award, and a Geological Society of America Student Research Grantto C.L.M. The version of TNTused in the cladistic analysis was producedwith support by the Willi Hennig Society. This is University of FloridaContribution to Paleobiology 679.

Appendix 1. Taxa Selected for Analysis and Sourcesof Data

OutgroupMaelestes gobiensisWible et al., 2007—Wible et al. (2007,

2009)Erinaceomorpha

Adunator minutus (Jepsen, 1930)—Jepsen (1930);Gingerich (1983); Secord (2008); YPM-PU 19463 (cast)

Macrocranion junnei Smith et al., 2002—Smith et al.(2002); Rose et al. (2012); UM 93378 (cast)Nyctitheriidae

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Plagioctenodon krausae Bown, 1979—Bown (1979);Bown and Schankler (1982)

Plagioctenodon savagei Bown and Schankler, 1982—Bown and Schankler (1982)

Plagioctenodon dormaalensis (Quinet, 1964)—Smith(1996) as Leptacodon dormaalensis

Plagioctenodon rosei (Gingerich, 1987)—Rose (1982) ascf. Leptacodon packi; Rose and Gingerich (1987) as cf.Leptacodon packi; Gingerich (1987) as Leptacodon rosei;UF 303728; UF 303729; UF 303730; UM 71650 (cast); UM76895 (cast); UM 77032 (cast)

Plagioctenodon thewisseni this publication— UM 39873;UM 76906; UM 76920; UM 82576; UM 83931; UM 86725;UF 289746; UF 289747; UF 294696

Leptacodon tener Matthew and Granger, 1921—Simpson(1935); McKenna (1968); Krishtalka (1976); Scott (2003)

Leptacodon munusculum Simpson, 1935—Krishtalka(1976); Gingerich et al. (1983); Krause and Gingerich(1983); Scott (2003)

Leptacodon catulus Krishtalka, 1976—Krishtalka (1976);Gheerbrant and Hartenberger (1999)

Leptacodon packi Jepsen, 1930—Jepsen (1930);Krishtalka (1976); Secord (2008)

Leptacodon nascimentoi Estravis, 1996—Estravis(1996)1

Leptacodon acherontus Secord, 2008—Secord (2008);YPM-PU 19957 (cast)

Leptacodon donkroni Rose et al., 2012—Rose et al. (2012)Leptacodon proserpinae2 Van Valen, 1978—Van Valen

(1978)Leptacodon choristus Secord, 2008—Secord (2008)Nyctitherium veloxMarsh, 1872—Robinson (1968); YPM

13510 (cast)Nyctitherium serotinum (Marsh, 1872)—Robinson (1968)Nyctitherium krishtalkai Christiansen and Stucky, 2013—

Christiansen and Stucky (2013)Nyctitherium christopheri Krishtalka and Setoguchi,

1977—Setoguchi (1973)as Nyctitherium robinsoni3;Krishtalka and Setoguchi (1977)

Acrodentis rosenorum Christiansen and Stucky, 2013—Christiansen and Stucky (2013)

Ceutholestes dolosus Rose and Gingerich, 1987—Roseand Gingerich (1987); UM 82503 (cast)

Limaconyssus habrusGingerich, 1987—Gingerich (1987);UM 86724 (cast)

Pontifactor bestiola West, 1974—West (1974); Bown(1979)

Wyonycteris chalix Gingerich, 1987—Gingerich (1987)Wyonycteris richardi Smith, 1995—Smith (1995)Wyonycteris primitivus Beard and Dawson, 2009—Beard

and Dawson (2009)Wyonycteris galensis Secord, 2008—Secord (2008); YPM-

PU 14138 (cast)Wyonycteris microtis Secord, 2008—Secord (2008); YPM-

PU 19479 (cast)Plagioctenoides microlestes Bown, 1979—Bown (1979);

Rose et al. (2012)Plagioctenoides tombowni Rose et al., 2012—Rose et al.

(2012)Amphidozotherium cayluxi Filhol, 1877—Sigé (1976)Saturninia gracilis Stehlin, 1940—Crochet (1974); Sigé

(1976)Saturninia mamertensis Sigé, 1976— Sigé (1976)Saturninia grandis Sigé, 1976— Sigé (1976)Saturninia rigasii Hooker and Weidman, 2000—Hooker

and Weidmann (2000)Saturninia ceciliensis Storch and Haubold, 1989—Storch

and Haubold (1989)Saturninia intermedia Sigé, 1976— Sigé (1976)Saturninia pirenaica Gibert Clols and Agustí Ballester,

1979—Gibert Clols and Agustí Ballester (1979); Sigé(1997); Ziegler (2007)

Saturninia pelissiei Sigé, 1997—Sigé (1997); Ziegler (2007)Saturninia carbonum Sigé and Storch, 2001—Sigé

(2001)Cryptotopos beatus Crochet, 1974—Crochet (1974); Sigé

(1976) as Saturninia beata; Hooker and Weidmann (2000);Ziegler (2007)

Cryptotopos woodi (Cray, 1973)—Cray (1973); Ziegler(2007)

Cryptotopos hartenbergi (Sigé, 1976)— Sigé (1976);Ziegler (2007)

Scraeva hatherwoodensis Cray, 1973—Cray 1973Placentidens lotusRussell et al.1973—Russell et al. (1973)Euronyctia montana Sigé, 1997— Sigé (1997)Euronyctia grisollensis (Sigé, 1976)—Sigé (1976); Sigé

(1997)Paradoxonycteris soricodonRevilliod, 1922—Hooker and

Weidman (2000)Asionyctia guoiMissiaen and Smith, 2005—Missiaen and

Smith (2005)Bumbanius rarus Russell and Dashzeveg, 1986—Russell

and Dashzeveg (1986); Lopatin (2006)Eosoricodon terrigena Lopatin, 2005—Lopatin (2005)

1 The codings for the M1 and M2 of Leptacodon nascimentoi were basedon Fig. 10 (SV3-300) and Fig. 9 (SV2-12), respectively, which is oppositeto how they are identified in Estravis (1996). See the reasoning in theBodyMass Calculations subsection of theMaterials andMethods section.2 Leptacodon proserpinae was taken out of the final analysis. It is onlymentioned in one publication with a single tooth, the P4, illustrated. Onlya small fraction of the characters in this analysis could be coded (8 of 66),which caused a great deal of instability in the placement of the taxon andresulted in a large polytomy in the strict consensus tree.3 The holotype specimen number in Setoguchi (1973) is given as TTM1219 but based on the figures, the specimen (broken P4,M1-M3) is the sameas the holotype for Nyctitherium christopheri in Krishtalka and Setoguchi(1977), although that specimen number is reported as CM 16996.

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Oedolius perexiguus Russell and Dashzeveg, 1986—Russell and Dashzeveg (1986); Lopatin (2006)

Edzenius lus Lopatin, 2006—Lopatin (2006)

Appendix 2. Unambiguous Synapomorphies for KeyNodes

Node A52 (1) upper molar stylocone absent61 (1) upper molar hypocone presentNode B: Adunator minutus + Macrocranion junnei22 (2) upper ultimate premolar postcingulum absent25 (2) M1 trigonid less wide than talonid26 (2) M2 trigonid less wide than talonid50 (1) M1 parastylar lobe anterolabially projecting63 (1) M3 parastylar lobe smallNode C: Nyctitheriidae14 (1) lower ultimate premolar paraconid lingual to

midline34 (1) lower molar paraconid anteriorly projecting37 (2) lower molar protoconid larger than metaconid46 (2) lower molar entoconid smaller than hypoconid66 (0) posteriormost mental foramen below penultimate

premolar or more anteriorNode D

15 (2) lower ultimate premolar metaconid present48 (1) upper molar length between 0.7-0.95 of the width

Node E: North American and European nyctitheriids17 (1) lower ultimate premolar talonid basin present18 (1 or 2) lower ultimate premolar talonid has two or three

cusps26 (1) M2 trigonid width subequal to talonid44 (0) lower molar hypoconulid positioned on midline46 (0) lower molar entoconid subequal in height to

hypoconid58 (2) upper molar paraconule lingual to metaconule and

closer to protoconeNode F

14 (0) lower ultimate paraconid on midline21 (0) upper ultimate premolar precingulum present33 (0) lower molar paraconid cuspate in shape37 (1) lowermolar protoconid andmetaconid subequal in size

Node G24 (1) upper ultimate premolar metacone present49 (0) M1 ectoflexus present54 (1) upper molar centrocrista strong and rectilinear55 (1) upper molar precingulum strong, reaching past

paraconuleNode H

11 (3) lower ultimate premolar width greater than 0.8 of thelength

14 (1) lower ultimate premolar paraconid lingual to midline

29 (1) M1 length greater than that of M2

40 (0) lower molar cristid obliqua meets the protocristidlingual to notch

47 (1) lower molar postcingulid presentNode I: Placentidens lotus + Ceutholestes dolosus

6 (1) lower penultimate premolar metaconid present37 (0) lower molar metaconid larger than protoconid46 (1) lower molar entoconid taller than hypoconid

Node J: Nyctitherium20 (1) anterodorsal shift in upper ultimate premolar visible

from labial view23 (1) upper ultimate premolar hypocone present56 (0) upper molar paraconule small, not strongly winged60 (1) upper molar postcingulum greatly expanded into shelf

Node K7 (1) lower penultimate premolar anteriorly canted

Node L8 (1) lower penultimate premolar smaller than surrounding

premolarsNode M: Plagioctenodon

12 (2) lower ultimate premolar paraconid present and highon anterior of trigonid

59 (1) upper molar paracone and metacone height subequalNode N

33 (1) lower molar paraconid crestiform in shape40 (2) lower molar cristid obliqua ascends the protocristid

to the tip of the metaconid55 (2) upper molar precingulum strong with pericone

Node O11 (1) lower ultimate premolar width between 0.5-0.65 of

the length43 (1) cristid obliqua is deeply concave occlusally44 (2) lower molar hypoconulid positioned lingually in

nyctalodont condition46 (1) lower molar entoconid taller than hypoconid66 (1) posteriormost mental foramen below ultimate pre-

molar or more posteriorNode P: Plagioctenoides

18 (0) lower ultimate premolar has one talonid cuspNode Q: Wyonycteris + Pontifactor

27 (0) lower molar trigonid anteroposteriorly compressedNode R: W. galensis + W. chalix + W. richardi + P. bestiola

16 (0) lower ultimate premolar talonid narrower thantrigonid or absent

31 (1) lower molar metaconid twinned33 (0) lower molar paraconid cuspate in shape53 (1) upper molar mesostyle present54 (2) upper molar centrocrista dilambdodont

Pontifactor bestiola autapomorphies55 (1) upper molar precingulum strong, reaching past

paraconule58 (1) upper molar paraconule lingual to metaconule and

halfway to protocone

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59 (1) upper molar paracone and metacone subequal60 (1) upper molar postcingulum greatly expanded into shelf

Node S22 (1) upper ultimate premolar postcingulum greatly ex-

panded into shelf23 (1) upper ultimate premolar hypocone present60 (1) upper molar postcingulum greatly expanded into shelf64 (1) dentary has one mental foramen

Node T: Cryptotopos?11 (3) lower ultimate premolar width greater than 0.8 of the

length33 (0) lower molar paraconid cuspate in shape42 (1) lower molar cristid obliqua has notch halfway along

the lengthNode U: Cryptotopos?

27 (0) lower molar trigonid anteroposteriorly compressed43 (2) cristid obliqua is convex occlusally54 (0) upper molar centrocrista absent or weak

Node V55 (0) upper molar precingulum absent or weak56 (0) upper molar paraconule small, not strongly winged57 (0) upper molar metaconule small, not strongly winged

Node W47 (1) lower molar postcingulid present

Node X: Paradoxonycteris + Euronyctia54 (2) upper molar centrocrista dilambdodont56 (2) upper molar paraconule large, not strongly winged57 (1) upper molar metaconule small, strongly winged

Node Y25 (0) M1 trigonid wider than talonid26 (0) M2 trigonid wider than talonid33 (0) lower molar paraconid cuspate in shape37 (2) lower molar protoconid larger than metaconid

Node Z: Scraeva + Limaconyssus13 (1) lower ultimate premolar paraconid is large cusp28 (0) lower molar trigonid height twice that of the talonid

Appendix 3. Characters Used in Cladistic Analysis

1. Lower incisor shape: conical (0), spatulate (1), or pectinate (2)2. Second lower incisor number of cusps: one (0), two (1),

three (2), four (3), or five (4)3. Lower canine posterior shelf or basal cusp: absent (0) or

present (1)4. Second lower premolar number of roots: two (0) or one (1)5. Lower penultimate premolar4 number of roots: two (0)

or one (1)

6. Lower penultimate premolar metaconid: absent (0) orpresent (1)

7. Lower penultimate premolar protoconid orientation:dorsoventral (0) or anteriorly canted (1)

8. Lower penultimate premolar size relative to other pre-molars: similarly sized to large (0) or small (1)

9. Upper penultimate premolar protocone: present (0) orabsent (1)

10. Upper penultimate premolar metacone: absent (0) orpresent (1)

11. Lower ultimate premolar shape (width/length):less than 0.5 (0), 0.5-0.65 (1), 0.65-0.8 (2), or morethan 0.8 (3)

12. Lower ultimate premolar paraconid position: absent(0), present and low on trigonid (1), or present and high ontrigonid (2)

13. Lower ultimate premolar paraconid size: absentor very small cuspule on low anterior cingulid (0) orlarge cusp (1)

14. Lower ultimate premolar paraconid or anterior-mostprojection of tooth position: on midline or buccal to midline(0) or lingual to midline (1)

15. Lower ultimate premolar metaconid: absent (0), swell-ing (1), or present (2)

16. Lower ultimate premolar width of talonid: narrowerthan trigonid (0) or as wide as or wider than trigonid (1)

17. Lower ultimate premolar talonid basin: absent (0) orpresent (1)

18. Lower ultimate premolar talonid number of cusps: one(0), two (1), or three (2)

19. Upper ultimate premolar highly waisted: present (0) orabsent (1)

20. Upper ultimate premolar anterodorsal shift (from labialview): absent (0) or present (1)

21. Upper ultimate premolar precingulum: present (0) orabsent (1)

22. Upper ultimate premolar postcingulum size: small (0),greatly expanded (1), or absent (2)

23. Upper ultimate hypocone: absent (0) or present (1)24. Upper ultimate premolar metacone: absent (0) or pres-

ent (1)25. M1 trigonid width: wider than talonid (0), equal to

talonid (1), or narrower than talonid (2)26. M2 trigonid width: wider than talonid (0), equal to

talonid (1), or narrower than talonid (2)27. Lower molar5 trigonid length: anteroposteriorly com-

pressed (0) or about equal to talonid or longer (1)28. Lower molar trigonid height: nearly twice the

height of the talonid (0), less than twice the height of4 Posterior premolars are referred to as penultimate and ultimate to avoidconfusion because Maelestes gobiensis has five premolars andnyctitheriids have four. It is understood that the third premolar is eventu-ally lost in eutherianswhen the count goes down to four, so that the P4 andP5 of Maelestes are homologous to the P3 and P4 of nyctitheriids.

5 For characters that just specify “lower molar” or “upper molar,” all taxawere coded using the second molar, if possible. If that position wasunknown, the first molar was used.

J Mammal Evol

the talonid (1), or nearly the same height as the talonid(2)

29. M1 and M2 length: subequal, within 5% (0), M1 longerthan M2 (1), or M2 longer than M1 (2)

30. M2 and M3 length: M3 longer than M2 (0), subequal,within 5% (1), or M2 longer than M3 (2)

31. Lower molar (more visible on the M1) metaconid“twinned,” or a groove runs alongside the cristidobliqua up the posterior surface of the metaconid: ab-sent (0) or present (1)

32. Lower molar precingulid: strong, anteriorly projecting(0) or reduced, not projecting (1)

33. Lower molar paraconid shape: cuspate (0) or crestiform(1)

34. Lower molar paraconid anteriorly projecting: absent (0)or present (1)

35. Lower molar paraconid position: on midline (0) orlingually positioned (1)

36. Lower molar protoconid position relative to metaconid:protoconid anterior to metaconid (0) or the cusps are trans-verse (1)

37. Lower molar protoconid and metaconid size:metaconid is larger (0), subequal (1), or protoconid is larger(2)

38. Lower molar protoconid and metaconid height:subequal (0), protoconid is taller (1), or metaconid istaller (2)

39. Lower molar labial cingulid: absent (0) or present alonglength of tooth (1)

40. Lower molar cristid obliqua position: ends lingual tonotch in protocristid (0), ends labial to notch in protocristid(1), or ascends to apex of metaconid (2)

41. Lower molar mesoconid on cristid obliqua: absent (0)or present (1)

42. Lower molar notch in cristid obliqua: absent(0), present, located halfway along cristid obliqua(1), or present, located on distal third of cristidobliqua (2)

43. Lower molar cristid obliqua shape in labial view:straight or slightly concave occlusally (0), deeply concaveocclusally (1), or convex occlusally (2)

44. Lower molar hypoconulid position: on midline(0), lingual to midline (1), close to entoconid innyctalodont condition6 (2), or incipient on postcingulidto absent (3)

45. Lower molar entoconid position: anterolingual tohypoconulid (0) or on posterolingual margin of tooth and evenposteriorly with hypoconulid (1)

46. Lower molar entoconid height: subequal to hypoconid(0) or taller than hypoconid (1)

47. Lower molar postcingulid: absent (0) or present(1)

48. Upper molar shape (length/width): less than 0.7 (0),0.7-0.95 (1), or greater than 0.95 (2)

49. M1 ectoflexus: present (0) or absent (1)50. M1 parastylar lobe orientation: anteriorly projecting (0)

or anterolabially projecting (1)51. M2 ectoflexus: present, relatively deep (0) or absent to

very shallow (1)52. Upper molar stylocone (stylar cusp B): present (0) or

absent (1)53. Upper molar mesostyle: absent (0) or present

(1)54. Upper molar centrocrista (between protocone and

metacone): absent or weak (0), strong, rectilinear (1), orstrong, dilambdodont (2)

55. Upper molar precingulum: unlobed and small (0),unlobed and large, reaching labially past paraconule (1),or with pericone (2)

56. Upper molar paraconule: small and not strongly winged(0), large and strongly winged (1), or large and not stronglywinged (2)

57. Upper molar metaconule: small and not stronglywinged (0), large and strongly winged (1), or large and notstrongly winged (2)

58. Upper molar paraconule and metaconule posi-tions: level with each other transversely, closer toparacone and metacone than protocone (0), paraconulemore lingual than metaconule and located halfway be-tween paracone and protocone, metaconule closer tometacone than protocone (1), or paraconule more lin-gual than metaconule and located closer to protoconethan paracone, metaconule halfway between metaconeand protocone (2)

59. Upper molar paracone and metacone height: paraconetaller than metacone (0) or subequal (1)

60. Upper molar postcingulum size: absent or small (0) orexpanded into a large shelf (1)

61. Upper molar hypocone: absent (0) or present (1)62. Upper molar postcingulum shape: flat posteriorly (0) or

rounded posteriorly (1)63. M3 parastylar lobe size: large, expanded anterolabially

(0) or small (1)64. Number of mental foramina: two (0) or one (1)65. Location of anteriormost mental foramen: below P1 or

anterior (0), below P2 (1), or below penultimate premolar orposterior

66. Location of posteriormost mental foramen (this char-acter is coded if only one mental foramen): below penultimatepremolar or more anterior (0), below ultimate premolar ormore posterior (1)

6 sensuMenu and Sigé 1971: The entoconid and hypoconulid are closelyappressed but separated by a fissure and the hypoconid and hypoconulidare connected by a crest.

J Mammal Evol

PLAGIOCTENODON_SAVAGEI ????0011??12102112???????111??0?0111?001000011???????????????????? PLAGIOCTENODON_DORMAALENSIS ???00??1??22002112100011[12]111010001111001000000010001011112101101-0 PLAGIOCTENODON_ROSEI 24100011012210211[12]100001211101000111100100000101[01]00101111210110[01]10 PLAGIOCTENODON_THEWISSENI 241000110102102112100001211101000111100100000101[01]00101011210110010 LEPTACODON_TENER ???0000010011021111000012111010001112101000000010?01011112[01]0110010 LEPTACODON_MUNUSCULUM ???00?????2[12]112012???00011110200100110010000100??????????????????? LEPTACODON_CATULUS ???00???0?31?120121?0001111111001?01100000?00?100001011112?0110??? LEPTACODON_PACKI ???00?00??2110201110000011111100011111110001000110010?011200010010 LEPTACODON_NASCIMENTOI ??????????1110201???????1111??0001110201000000011001002012?0110??? LEPTACODON_ACHERONTUS ????0010??21102112???????1110100010110010000000??????????????????0 LEPTACODON_DONKRONI 23??0??0??1????111011000?1112?00100120010000000?10?100011200010??0 LEPTACODON_CHORISTUS ????0010??32102011??????11110000010112010001000??????????????????? NYCITHERIUM_VELOX ???00000??1111201[12]11011121010100011110120011001101011110011111?1-0 NYCTITHERIUM_SEROTINUM ??????????1111201110011111010101011110020011001??????1?????????010 NYCTITHERIUM_KRISHTALKAI ???000000011112011110011100111010111120000?101?1010100101101110000 NYCTITHERIUM_CHRISTOPHERI ??????????????????111111???????????????????????0010101000111110??? ACRODENTIS_ROSENORUM ???00???00111020111000011101210101111200001100?10101011111001101-0 CEUTHOLESTES_DOLOSUS 23100100??32112112??????21011101011102000011011????????????????010 LIMACONYSSUS_HABRUS ???00?????12102012??????00101200011121020011001????????????????010 PONTIFACTOR_BESTIOLA ??????????????????1?0001???????????????????????1101012111111110??? WYONYCTERIS_CHALIX ??????????11?02012??????21010?110111110200120101101112211200100??1 WYONYCTERIS_RICHARDI ???10011??11102012??????210112100111100200120101101012211200110021 WYONYCTERIS_PRIMITIVUS ??????????01102112??????2?01??011111100200?2011?10110121120011???? WYONYCTERIS_GALENSIS ???00?????3110201???????11010211011111120012010????????????????011 WYONYCTERIS_MICROTIS ???????????????????????????????????????????????00000100112000-0??? PLAGIOCTENOIDES_MICROLESTES ???11001??11102110??????2?11??10111110020012010????????????????011 PLAGIOCTENOIDES_TOMBOWNI ???10?????11102110???????111?200111110020012010????????????????011 AMPHIDOZOTHERIUM_CAYLUXI 23111011??3100211[012]1111110011020000012102021[01]001110?10000030111?1-0 SATURNINIA_GRACILIS 2?100011002110211[012]1101111111020[01][01]101[12]100000000110001000002011101-0 SATURNINIA_MAMERTENSIS ??100??1??111?21121101111111?20[01][01]11???020000000000110?0002?11101-0 SATURNINIA_GRANDIS 2?1?0001??21002?1???????1?11??001101100010000000???10?2112?1110??? SATURNINIA_RIGASII ??????????1100201???????00110?00010121001000001??????????????????0 SATURNINIA_CECILIENSIS ????????????????????????1111010011012?010000000??????????????????? SATURNINIA_INTERMEDIA ??????????31102112????????11??000101??02?1000?11???1012212?1110??? SATURNINIA_PIRENAICA ??????????2????????????????1??0?111???0????0?00?????012212?111???? SATURNINIA_PELISSEI ??????????3????????????????????????????2??????0?0001012212?111???? SATURNINIA_CARBONUM 23100011??31002?1????????101?001?1012101?001000????????????????1-0 CRYPOTOTOPOS_BEATUS 2?10001100[23]1[01]0211[12]1001111101010001011002112000010001002212011101-0 CRYPTOTOPOS_WOODI ???00?????11112012??????1?010101010121021120000????????????????1-0 CRYPTOTOPOS_HARTENBERGI ??10001101[23]100211[12]1101111101010[01][01]10121021120000[01]??01002212?11101-0 SCRAEVA_HATHERWOODENSIS ???00?????21102012??????00100?00010021021??0000????????????????1-0 PLACENTIDENS_LOTUS_P3 ????0100????????????????2111?2100110020200?3011?000101211[01]?011???? EURONYCTIA_MONTANA ??1000????310021121?11112?11?21011011?02021100111001020212?1110??? EURONYCTIA_GRISOLLENSIS 23?00001??[23]1[01]021121??1111111020[01][01]100100202110011???1020212?11101-0 PARADOXONYCTERIS_SORICODON ??????????????????1?1111??????????????????10001??001020212?111???? ASIONYCTIA_GUOI ???00000??121100001010001011010011112101000100001001010111001000[12]1 BUMBANIUS_RARUS ???00000??11112000??????10110100111[01]00010011020110010001110010???0 EOSORICODON_TERRIGENA ???10000??21111000??????001101001111210[12]0011020110010?020100110010 OEDOLIUS_PEREXIGUUS ???0001???01010000??????1011010011101?020010020????????????????0[01]0 EDZENIUS_LUS ???00?????01011000??????0?01??01011120010000020??????????????????0

MAELESTES_GOBIENSIS 000000000000000000000000000000000000000000000000000000000000000011 ADUNATOR_MINUTUS 100000000112101011101201221102001011000100000000010100011100101011 MACROCRANION_JUNNEI ????????102100100010120022011?011010100100000100010100022100101011 PLAGIOCTENODON_KRAUSAE ???00011??1210211[12]??000?1111010?0111?001000011???0??0?1112?01??020

Appendix 4. Data Matrix Used in Cladistic Analysis

J Mammal Evol

References

Archibald JD, Averianov AO, Ekdale EG (2001) Late Cretaceous rela-tives of rabbits, rodents, and other extant eutherian mammals.Nature 414:62–5

Averianov AO, Archibald JD (2013) Newmaterial and reinterpretation ofthe Late Cretaceous eutherian mammal Paranyctoides fromUzbekistan. Acta Palaeontol Pol 58:17–23

De Bast E, Sigé B, Smith T (2012) Diversity of the adapisoriculidmammals from the early Palaeocene of Hainin, Belgium. ActaPalaeontol Pol 57:35–52

Beard K, Dawson M (1999) Intercontinental dispersal of Holarctic landmammals near the Paleocene/Eocene boundary: paleogeographic,paleoclimatic and biostratigraphic implications. Bull Soc Géol Fr170:697–706

Beard K, Dawson M (2009) Early Wasatchian mammals of the Red HotLocal Fauna, uppermost Tuscahoma Formation, Lauderdale County,Mississippi. Ann Carnegie Mus 78:193–243

Bloch J (2001) Mammalian paleontology of freshwater limestones fromthe Paleocene-Eocene of the Clarks Fork Basin, Wyoming.Dissertation, University of Michigan, Ann Arbor

Bloch J, Bowen G (2001) Paleocene-Eocene microvertebrates in fresh-water limestones of the Willwood Formation, Clarks Fork Basin,Wyoming. In: Gunnell GF (ed) Eocene Biodiversity. KluwerAcademic/Plenum, New York, pp 95–129

Bloch J, Boyer D (2001) Taphonomy of small mammals infreshwater limestones from the Paleocene of the ClarksFork Basin. Paleocene–Eocene stratigraphy and biotic changein the Bighorn and Clarks Fork basins, Wyoming. UnivMichigan Pap Paleontol 33:185–198

Bloch JI, Rose KD, Gingerich PD (1998) New species of Batodonoides(Lipotyphla, Geolabididae) from the early Eocene of Wyoming:smallest known mammal? J Mammal 79:804–827

Bloch JI, Silcox MT, Boyer DM, Sargis EJ (2007) New Paleoceneskeletons and the relationship of plesiadapiforms to crown-cladePrimates. Proc Natl Acad Sci USA 104:1159–1164

Bowen GJ, Bloch JI (2002) Petrography and geochemistry of floodplainlimestones from the Clarks Fork Basin, Wyoming, U.S.A.: carbon-ate deposition and fossil accumulation on a Paleocene-Eocenefloodplain. J Sediment Res 72:46–58

Bowen GJ, ClydeWC, Koch PL, Ting S, Alroy J, Tsubamoto T, Wang Y,Wang Y (2002) Mammalian dispersal at the Paleocene/Eoceneboundary. Science 295:2062–2065

Bown TM (1979) Geology and mammalian paleontology of the SandCreek facies, lower Willwood Formation (lower Eocene), WashakieCounty, Wyoming. Wyoming Geol Surv Mem 2:1–151

Bown TM, Schankler D (1982) A review of the Proteutheria andInsectivora of the Willwood Formation (lower Eocene), BighornBasin, Wyoming. US Geol Surv Bull 1532:1–79

Butler PM (1988) Phylogeny of the insectivores. In: Benton MJ (ed) ThePhylogeny of the Tetrapods, Vol. 2: Mammals. Clarendon Press,Oxford, pp 117–141

Chester SGB, Bloch JI, Secord R, Boyer DM (2010) A new small-bodiedspecies of Palaeonictis (Creodonta, Oxyaenidae) from thePaleocene-Eocene Thermal Maximum. J Mammal Evol 17:227–243

Christiansen MG, Stucky RK (2013) Revision of the Wind River Faunas,early Eocene of central Wyoming. Part 15. New Nyctitheriidae(?Lipotyphla) with analysis of the relationships of North Americantaxa. Denver Mus Nat Sci Ann 1–16

Cray PE (1973) Marsupialia, Insectivora, Primates, Creodonta, andCarnivora from the Headon Beds (Upper Eocene) of southernEngland. Bull Brit Mus (Nat Hist) Geol 23:1–102

Crochet J (1974) Les insectivores des phosphorites du Quercy.Palaeovertebrata 6:109–159

Dawson M, Krishtalka L (1984) Fossil history of the families of Recentmammals. In: Anderson S, Jones JK Jr (eds) Orders and Families ofRecent Mammals of the World. John Wiley & Sons, New York, pp11–57

Estravis C (1996) Leptacodon nascimentoi n. sp., un nouveauNyctitheriidae (Mammalia, Lipotyphla) de l’Eocène inférieur deSilveirinha (Baixo Mondego, Portugal). Palaeovertebrata 25:279–286

Gheerbrant E, Hartenberger JL (1999) Nouveau mammifère insectivore(? Lipotyphla,? Erinaceomorpha) de l’Eocène inférieur de Chambi(Tunisie). Paläontol Z 73:143–156

Gheerbrant E, Russell DE (1989) Presence of the genus Afrodon[Mammalia, Lipotyphla (?), Adapisoriculidae] in Europe; new datafor the problem of trans-Tethyan relations between Africa andEurope around the K/T boundary. Palaeogeogr PalaeoclimatolPalaeoecol 76:1–15

Gibert Clols J, Agustí Ballester J (1979) Insectívoros (Nyctitheriidae,Soricidae, Apatemyidae) del Paleógeno catalán. Acta Geol Hisp14:347–350

Gingerich PD (1982) Studies on Paleocene and early EoceneApatemyidae (Mammalia, Insectivora). II. Labidolemur andApatemys from the early Wasatchian of the Clarks Fork Basin,Wyoming. Contrib Mus Paleontol Univ Mich, 27: 275–320

Gingerich PD (1983) New Adapisoricidae, Pentacodontidae, andHyopsodontidae (Mammalia, Insectivora, and Condylarthra) fromthe late Paleocene of Wyoming and Colorado. Contrib MusPaleontol Univ Mich 26:227–255

Gingerich PD (1987) Early Eocene bats (Mammalia, Chiroptera) andother vertebrates in freshwater limestones of the WillwoodFormation, Clark’s Fork Basin, Wyoming. Contrib Mus PaleontolUniv Mich 27:275–320

Gingerich PD (2006) Environment and evolution through the Paleocene-Eocene Thermal Maximum. Trends Ecol Evol 21:246–253

Gingerich PD, Deutsch HA (1989) Systematics and evolution of earlyEocene Hyaenodontidae (Mammalia, Creodonta) in the Clarks ForkBasin, Wyoming. Contrib from Museum Paleontol Univ Michigan135:327–391

Gingerich PD, Gunnell GF (1992) A new skeleton of Plesiadapis cookei.Display Case, A Quarterly Newsletter of the Exhibit Museum,University of Michigan 6:1–3

Gingerich PD, Gunnell GF (2005) Brain of Plesiadapis cookei(Mammalia, Proprimates): surface morphology and encephalizationcompared to those of Primates and Dermoptera. Contrib MusPaleontol Univ Mich 31:185–195

Gingerich PD, Houde P, Krause DW (1983) A new earliest Tiffanian (latePaleocene) mammalian fauna from Bangtail Plateau, western CrazyMountain Basin, Montana. J Paleontol 57:957–970

Godinot M (1981) Les mammifères de Rians (Eocène inférieur,Provence). Palaeovertebrata 10:43–126

Goloboff PA, Farris JS, Nixon KC (2008) TNT, a free program forphylogenetic analysis. Cladistics 24:774–786

Gunnell GF, Bown TM, Hutchison JH, Bloch JI (2008) Lipotyphla. In:Janis CM, Gunnell GF, Uhen MD (eds) Evolution of TertiaryMammals of North America, Vol. 2: Small Mammals,Xenarthrans, and Marine Mammals. Cambridge University Press,New York, pp 89–125

Gunnell GF, Gingerich PD (1987) Skull and partial skeleton of Plesiadapiscookei from the Clarks Fork Basin. Am J Phys Anthropol 72:206

Hand S, Novacek MJ, Godthelp H, Archer M (1994) First Eocene batfrom Australia. J Vertebr Paleontol 14:375–381

Hooker JJ (2001) Tarsals of the extinct insectivoran family Nyctitheriidae(Mammalia): evidence for archontan relationships. Zool J Linn Soc132:501–529

Hooker JJ, Russell DE (2012) Early Palaeogene Louisinidae(Macroscelidea, Mammalia), their relationships and northEuropean diversity. Zool J Linn Soc 164:856–936

J Mammal Evol

Hooker JJ, Weidmann M (2000) The Eocene mammal faunas ofMormont, Switzerland: systematic revision and resolution of datingproblems. Abh Schweiz Paläontol Ges 120:1–143

Houde P (1986) Ostrich ancestors found in the Northern Hemispheresuggest new hypothesis of ratite origins. Nature 324:563–565

Houde P (1987) Critical evaluation of DNA hybridization studies in aviansystematics. Auk 104:17–32

Jepsen GL (1930) Stratigraphy and paleontology of the Paleocene ofnortheastern Park County, Wyoming. Proc Am Philos Soc 69:463–528

Krause DW, Gingerich PD (1983) Mammalian fauna from DouglassQuarry, earliest Tiffanian (late Paleocene) of the eastern CrazyMountain Basin, Montana. Contrib Mus Paleontol Univ Mich 26:157–196

Krause DW,MaasM (1990) The biogeographic origins of late Paleocene-early Eocene mammalian immigrants to the Western Interior ofNorth America. Geol Soc Am Spec Pap 243:71–105

Krishtalka L (1976) North American Nyctitheriidae (Mammmalia,Insectivora). Ann Carnegie Museum 46:7–28

Krishtalka L, Setoguchi T (1977) Paleontology and geology of theBadwater Creek area, central Wyoming. Part 13. The late EoceneInsectivora and Dermoptera. Ann Carnegie Museum 46:71–99

Lopatin AV (2005) A new soricomorph insectivore (Soricomorpha,Mammalia) from the Eocene of Mongolia and the origin of shrews(Soricidae). Dokl Biol Sci 401:842–844

Lopatin AV (2006) Early Paleogene insectivore mammals of Asia andestablishment of the major groups of Insectivora. Paleontol J 40:S205–S405

Marandat B (1991) Mammifères de l’Ilerdien moyen (Eocène inférieur)des Corbières et du Minervois (Bas-Languedoc, France):Systématique, biostratigraphie, corrélations. Palaeovertebrata 20:55–144

Marsh OC (1872) Preliminary description of new Tertiary mammals. PartI. Am J Sci 4:122–128

Matthew WD, Granger W (1921) New genera of Paleocene mammals.Am Mus Novitates 13:1–7

McKenna MC (1968) Leptacodon, an American Paleocene nyctithere(Mammalia, Insectivora). Am Mus Novitates 2317:1–12

McKenna MC, Bell SK (1997) Classification of Mammals above theSpecies Level. Columbia University Press, New York

Menu H, Sigé B (1971) Nyctalodontie et myotodontie; importantcaractères de grades évolutifs chez les Chiroptères entomophages.Comptes Rendus Acad Sci Paris D 272:1735–1738

Missiaen P (2011) An updated mammalian biochronology and biogeog-raphy from the early Paleogene of Asia. Vertebr Palasiat 49:29–52

Missiaen P, Smith T (2005) A new Paleocene nyctitheriid insectivorefrom Inner Mongolia (China) and the origin of Asian nyctitheriids.Acta Palaeontol Pol 50:513–522

Novacek MJ, Bown TM, Schankler D (1985) On the classification of theearly Tertiary Erinaceomorpha (Insectivora, Mammalia). Am MusNovitates 2813:1–22

Penkrot TA, Zack SP, Rose KD, Bloch JI (2008) Postcranial morphologyof Apheliscus and Haplomylus (Condylarthra, Apheliscidae): evi-dence for a Paleocene Holarctic origin of Macroscelidea. In: SargisEJ, Dagosto M (eds) Mammalian Evolutionary Morphology: ATribute to Frederick S. Szalay. Springer Netherlands, Dordrecht,pp 73–106

Revilliod P (1922) Contribution à l’étude des chiroptères des terrainstertiaires. Troisième partie et fin. Abh Schweiz Paläontol Ges 45:133–195

Robinson P (1968) Nyctitheriidae (Mammalia, Insectivora) from theBridger Formation of Wyoming, USA. Contrib Geol UnivWyoming 7:129–138

Rose KD (1981) The Clarkforkian Land-Mammal Age and mammalianfaunal composition across the Paleocene-Eocene boundary. UnivMich Pap Paleontol 26:1–197

Rose KD, Chester SGB, Dunn RH, Boyer DM, Bloch JI (2011) Newfossils of the oldest North American euprimate Teilhardina brandti(Omomyidae) from the Paleocene-Eocene Thermal Maximum. AmJ Phys Anthropol 146:281–305

Rose KD, Chew AE, Dunn RH, Kraus MJ, Fricke HC, Zack SP (2012)Earliest Eocene mammalian fauna from the Paleocene-EoceneThermal Maximum at Sand Creek Divide, southern BighornBasin, Wyoming. Univ Mich Pap Paleontol 36:1–122

Rose KD, Gingerich PD (1987) A new insectivore from the Clarkforkian(earliest Eocene) of Wyoming. J Mammal 68:17–27

Rose KD, Storch G, Krohmann K (2013) Small-mammalpostcrania from the middle Paleocene of Walbeck, Germany.Paläontol Z 1–30

Russell DE, Dashzeveg D (1986) Early Eocene insectivores (Mammalia)from the People’s Republic of Mongolia. Palaeontology 29:269–291

Russell D, Louis P, Savage D (1973) Chiroptera and Dermoptera of theFrench early Eocene. Univ Calif Publ Geol Sci 95:1–57

Scott CS (2003) Late Torrejonian (middle Paleocene) mammals fromsouth central Alberta, Canada. J Paleontol 77:745–768

Secord R (2008) The Tiffanian Land-Mammal Age (middle and latePaleocene) in the northern Bighorn Basiin, Wyoming. Univ MichPap Paleontol 35:1–192

Setoguchi T (1973) The late Eocene marsupials and insectivores from theTepee Trail Formation, Badwater, Wyoming. Dissertation, TexasTech University, Lubbock

Sigé B (1976) Insectivores primitifs de l’Eocene superieur et Oligoceneinferieur d'Europe occidentale. Mem Mus Natl Hist Nat 34:1–140

Sigé B (1997) Les mammifères insectivores des nouvelles collection deSossís et sites associés (Éocène Supérieur, Espagne). Géobios 30:91–113

Sigé B, Storch G (2001) Un nouveau Saturninia (Nyctitheriidae,Lipotyphla, Mammalia) de l’assise OK (Oberkohle, MP 14) dubassin lignitifère du Geiseltal (Eocène moyen supérieurd'Allemagne). Senckenberg Lethaea 81:343–346

Silcox MT, Bloch JI, Sargis EJ, Boyer DM (2005) Euarchonta(Dermoptera, Scandentia, Primates). In: Rose KD, Archibald JD(eds) The Rise of Placental Mammals: Origins and Relationshipsof the Major Extant Clades. The Johns Hopkins University Press,Baltimore, pp 127–144

Simpson GG (1928) A new mammalian fauna from the Fort Union ofsouthern Montana. Am Mus Novitates 297:1–15

Simpson GG (1935) The Tiffany Fauna, upper Paleocene: I.Multituberculata, Marsupialia, Insectivora, and ?Chiroptera. AmMus Novitates 795:1–20

Smith R (2004) Insectivores (Mammalia) from the earliest Oligocene(MP 21) of Belgium. Netherlands J Geosci 83:187–192

Smith T (1995) Présence du genreWyonycteris (Mammalia, Lipotyphla) àla limite Paléocène-Eocène en Europe. Comptes Rendus Acad Sci321:923–930

Smith T (1996) Leptacodon dormaalensis (Mammalia, Lipotyphla), unnyctithere primitif de la transition Paleocene-Eocene en Europe.Belgian J Zool 126:153–167

Smith T, Bloch JI, Strait SG, Gingerich PD (2002) New species ofMacrocranion (Mammalia, Lipotyphla) from the earliest Eoceneof North America and its biogeographic implications. Contrib MusPaleontol Univ Mich 30:373–384

Smith T, Rose KD, Gingerich PD (2006) Rapid Asia-Europe-NorthAmerica geographic dispersal of earliest Eocene primateTeilhardina during the Paleocene-Eocene Thermal Maximum.Proc Natl Acad Sci USA 103:11223–11227

Smith T, Smith R (1996) Synthèse des données actuelles sur les vertébrésde la transition Paléocène-Eocène de Dormaal (Belgique). Bull Socbelge Géol, 104(1–2): 119–131

Storch G, Haubold H (1989) Additions to the Geiseltal mammalianfaunas, middle Eocene: Didelphidae, Nyct i theri idae,Myrmecophagidae. Palaeovertebrata 19:95–114

J Mammal Evol

Szalay F, Drawhorn G (1980) Evolution and diversification of theArchonta in an arboreal milieu. In: Luckett WP (ed) ComparativeBiology and Evolutionary Relationships of Tree Shrews. PlenumPress, New York, pp 133–169

Tong Y (1997)Middle Eocene small mammals from Liquanqiao Basin ofHenan Province and Yuanqu Basin of Shanxi Province, CentralChina. Palaeontol Sin Ser C 26:1–256

Van Valen L (1978) The beginning of the Age of Mammals. Evol Theory4:45–80

West RM (1974) New North American middle Eocene nyctithere(Mammalia, Insectivora). J Paleontol 48:983–987

Wible JG, Rougier GW, Novacek M, Asher R (2007) Cretaceous euthe-rians and Laurasian origin for placental mammals near the K/Tboundary. Nature 447:1003–1006

Wible JR, Rougier GW, Novacek MJ, Asher RJ (2009) The eutherian mam-mal Maelestes gobiensis from the late Cretaceous of Mongolia and thephylogeny of Cretaceous Eutheria. Bull AmMus Nat Hist 327:1–123

Woodburne MO (2004) Late Cretaceous and Cenozoic Mammals ofNorth America. Columbia University Press, New York, 391 pp

Ziegler R (2007) The nyctitheriids (Lipotyphla, Mammalia) from earlyOligocene fissure fillings in south Germany. Neues Jahrb Für GeolPaläontol Abh 246:183–203

J Mammal Evol