Taphonomy of fossils from the hominin-bearing deposits at Dikika, Ethiopia

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Journal of Human Evolution xxx (2015) 1e24

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Journal of Human Evolution

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Taphonomy of fossils from the hominin-bearing deposits at Dikika,Ethiopia

Jessica C. Thompson a, *, Shannon P. McPherron b, Ren�e Bobe c, Denn�e Reed d,W. Andrew Barr c, Jonathan G. Wynn e, Curtis W. Marean f, g, Denis Geraads b, h,Zeresenay Alemseged i

a Department of Anthropology, Emory University, 1557 Dickey Drive, Atlanta, GA 30322, USAb Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, D-04103 Leipzig, Germanyc Department of Anthropology and Center for the Advanced Study of Human Paleobiology, The George Washington University, 2110 G St., NW, Washington,DC 20052, USAd Department of Anthropology, University of Texas at Austin, 2201 Speedway, Stop C3200, Austin, TX 78712, USAe School of Geosciences, University of South Florida, 4202 E Fowler Ave, NES107, Tampa, FL 33620, USAf Institute of Human Origins, School of Human Evolution and Social Change, Arizona State University, PO Box 874101, Tempe, AZ 85287-4101, USAg Faculty of Science, Nelson Mandela Metropolitan University, Port Elizabeth, Eastern Cape 6031, South Africah Centre de Recherche sur la Pal�eobiodiversit�e et les Pal�eoenvironnements (UMR 7207), Sorbonne Universit�es, MNHN, CNRS, UPMC, CP 38, 8 rue Buffon,75231 PARIS Cedex 05, Francei Department of Anthropology, California Academy of Sciences, 55 Concourse Drive, San Francisco, CA 94118, USA

a r t i c l e i n f o

Article history:Received 17 March 2015Accepted 30 June 2015Available online xxx

Keywords:TaphonomyEarly hominin subsistencePliocene hominin behaviorCut marksTrampling marks

* Corresponding author.E-mail addresses: [email protected] (

(D. Reed), [email protected] (W.A. Barr), jwynncalacademy.org (Z. Alemseged).

http://dx.doi.org/10.1016/j.jhevol.2015.06.0130047-2484/© 2015 Elsevier Ltd. All rights reserved.

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a b s t r a c t

Two fossil specimens from the DIK-55 locality in the Hadar Formation at Dikika, Ethiopia, are contem-poraneous with the earliest documented stone tools, and they collectively bear twelve marks interpretedto be characteristic of stone tool butchery damage. An alternative interpretation of the marks has beenthat they were caused by trampling animals and do not provide evidence of stone tool use or largeungulate exploitation by Australopithecus-grade hominins. Thus, resolving which agents created markson fossils in deposits from Dikika is an essential step in understanding the ecological and taphonomiccontexts of the hominin-bearing deposits in this region and establishing their relevance for in-vestigations of the earliest stone tool use. This paper presents results of microscopic scrutiny of all non-hominin fossils collected from the Hadar Formation at Dikika, including additional fossils from DIK-55,and describes in detail seven assemblages from sieved surface sediment samples. The study is the firsttaphonomic description of Pliocene fossil assemblages from open-air deposits in Africa that werecollected without using only methods that emphasize the selective retention of taxonomically-informative specimens. The sieved assemblages show distinctive differences in faunal representationand taphonomic modifications that suggest they sample a range of depositional environments in thePliocene Hadar Lake Basin, and have implications for how landscape-based taphonomy can be used toinfer past microhabitats. The surface modification data show that no marks on any other fossils resemblein size or shape those on the two specimens from DIK-55 that were interpreted to bear stone toolinflicted damage. A large sample of marks from the sieved collections has characteristics that matchmodern trampling damage, but these marks are significantly smaller than those on the DIK-55 specimensand have different suites of characteristics. Most are not visible without magnification. The data showthat the DIK-55 marks are outliers amongst bone surface damage in the Dikika area, and that trampling isnot the most parsimonious interpretation of their origin.

© 2015 Elsevier Ltd. All rights reserved.

J.C. Thompson), [email protected] (S.P. McPherron), [email protected] (R. Bobe), [email protected]@cas.usf.edu (J.G. Wynn), [email protected] (C.W. Marean), [email protected] (D. Geraads), zalemseged@

, J.C., et al., Taphonomy of fossils from the hominin-bearing deposits at Dikika, Ethiopia, Journal of0.1016/j.jhevol.2015.06.013

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J.C. Thompson et al. / Journal of Human Evolution xxx (2015) 1e242

1. Introduction

Tool-assisted butchery is one of many taphonomic processesthat may act on bones while they still contain nutritive value in theform of meat, marrow, or bone grease (i.e. a nutritive state).Butchery leaves marks on bone surfaces that provide direct evi-dence for hominin processing of animal tissues in the past. How-ever, taphonomic processes are prone to equifinality e wheredifferent processes lead to overlapping or indistinguishable endresults. Butchery traces can be difficult to distinguish from marksleft by very different processes that bring stone into contact withbone, such as trampling (Behrensmeyer et al., 1986; Olsen andShipman, 1988; Domínguez-Rodrigo et al., 2009) or natural rockfalls (Oliver, 1989; Fernandez-Jalvo, 2012; Karr and Outram, 2012).At a superficial level, carnivore tooth marks may also resemblecertain types of butchery marks, such as percussion marks(Blumenschine and Selvaggio, 1988), and carnivore tooth marksmay also be mimicked in turn by processes such as microbial bio-erosion (Domínguez-Rodrigo and Barba, 2006). In most cases,microscopic studies using modern taphonomic reference collec-tions allow for the correct diagnosis of these modifications(Blumenschine et al., 1996). However, when disagreements do ariseregarding the agent(s) behind their production, this can lead toquite different interpretations of the ecological and behavioralcontexts of the fossils on which the modifications are found.

This has been the case at DIK-55, a Pliocene locality within theDikika Research Project (DRP) area of the Lower Awash Valley inEthiopia (Fig. 1). Here, we examine alternative interpretations ofthe modified DIK-55 fossils (Domínguez-Rodrigo et al., 2010;McPherron et al., 2010; Domínguez-Rodrigo et al., 2012) throughstudy of surface modifications on all non-hominin fossils collectedfrom the Hadar Formation at Dikika. The sample includes addi-tional fossils fromDIK-55, as well as seven assemblages from sieved

Figure 1. Overview map of the DRP a

Please cite this article in press as: Thompson, J.C., et al., Taphonomy of fosHuman Evolution (2015), http://dx.doi.org/10.1016/j.jhevol.2015.06.013

surface sediment samples. This enables comparisons of the size,shape, and attributes of the marks reported in 2010 to a largesample of other marks from the same deposits. We also presentdata on bone weathering, rounding, and other post-depositionalprocesses that illustrate the utility of landscape taphonomic ap-proaches to understanding the context of fossils found on Pliocenedepositional landscapes.

2. Background

2.1. Ecological context of the DIK-55 specimens

At DIK-55, two large-mammal fossils bear surface marks (DIK-55-2, an adult rib; and DIK-55-3, a juvenile femur) interpreted byMcPherron et al. (2010) to be a mix of cutting and percussiondamage from stone tools, along with some modifications deemedunidentifiable. Two other fossil specimens that were examined didnot preserve any modification considered to be attributable tohominin butchery. However, because these fossils date to over 3.39million years ago (Ma), any butchery marks on themwould indicatethat hominins wielded stone tools to process large mammal re-sources prior to the emergence of Homo. Although this is roughlycontemporaneous with stone tools dated to 3.3 Ma at Lomekwi 3,Kenya (Harmand et al., 2015), large ungulate resource exploitationinvokes scenarios of australopith diet, ecology, and social behaviorthat depart from those of great apes and from models of earlierhominin ecology such as those proposed for Ardipithecus spp.(White et al., 2009). Thus, if the DIK-55marks were caused by stonetool butchery, a revised model of early hominin behavior andecology would be required. Since flaked stone artifacts or un-flakedbut utilized stone have not been found at DIK-55, they would alsoprovide an independent way of identifying ancient archaeologicaloccurrences on Pliocene landscapes.

rea relative to other study areas.

sils from the hominin-bearing deposits at Dikika, Ethiopia, Journal of

J.C. Thompson et al. / Journal of Human Evolution xxx (2015) 1e24 3

Reconstructions of australopith diet and the environments inwhich they subsisted have been critical areas of paleoanthropo-logical research for decades (Behrensmeyer and Reed, 2013;Stewart, 2014), which is why it is important to fully explore theutility of bone surface modifications as an additional line of inquiry.Current evidence suggests that a shift in diet occurred in thehominin lineage between 3 and 4 Ma, which may have derivedfrom either a change in the foods that were selected within thesame resource regime, or a change in the resources that wereavailable overall (Lee-Thorp et al., 2010; Sponheimer et al., 2013). Atthis time, hominins began to more intensively exploit C4 basedresources, although grassland environments had been presentacross northeastern Africa since the Late Miocene (Cerling et al.,1993, 2013; Feakins et al., 2013). Carbon isotopic evidence fromAustralopithecus afarensis indicates a diet that was highly variablebetween individuals, including some individuals with diets largelybased on foods which use the C4 and/or CAM photosyntheticpathway (tropical grasses, sedges, and succulents), and/or herbi-vores/insects that fed upon those foods (Wynn et al., 2013). Thiscontrasts with results from extant African apes and earlier homi-nins, such as Ardipithecus ramidus (White et al., 2009) and evenfrom the morphologically similar and presumed parent species ofAu. afarensis, Australopithecus anamensis, which consumed rela-tively few C4 and/or CAM foods in comparison to later homininse asignature more consistent with closed-habitat foraging (Cerlinget al., 2013; Sponheimer et al., 2013).

The facial architecture of Australopithecus spp. suggests adap-tations for heavy chewing loads (Strait et al., 2009). Fallback foodshave been proposed as primary selective drivers for shapingmorphological adaptations, behavior, and socioecology in primates(Marshall and Wrangham, 2007), and hard-object feeding (such ason nuts) has been proposed as an important fallback strategy thatwould have been accommodated by both australopith facialmusculature and tooth topography (Ungar, 2004). However, dentalmicrowear evidence from both Au. africanus (Scott et al., 2005) andAu. afarensis (Ungar et al., 2010) shows a highly variable diet withlast meals mostly comprising either soft or toughmaterials. Animaltissues may be quite tough and require significant masticatoryeffort (Wrangham and Conklin-Brittain, 2003), but this is notproblematic if only small amounts of meat were eaten (Harduset al., 2012). Thus, the degree to which ungulate tissues wereincorporated into the diet remains unknown, but its consumptionis not precluded by any of the anatomical features or geochemicaldietary reconstructions in Australopithecus.

2.2. The DIK-55 specimens

McPherron et al. (2010) interpreted most (but not all) of themarks on the two DIK-55 specimens as inflicted by stone tools at orbefore the time of fossilization. The interpretation of twelve of themarks as being stone-tool inflicted was based on microscopic ob-servations of their morphologies made blindly between experi-enced researchers, each of whom had passed with at least 95%accuracy blind tests of bone surface modifications on experimentalassemblages where the source of the marks was known(Blumenschine et al., 1996). They converged in their interpretationof all twelvemarks as being stone-tool inflicted and in six cases alsoconverged more specifically on whether the action was cutting,percussion, or a combination of both (McPherron et al., 2010; theirSupplementary Table 3). In addition to the morphological featuresof the marks and their anatomical placements, both scanningelectron microscopy (SEM) and light microscopy showed a highincidence of microstriations, which are more common in stone-toolinflicted marks than in carnivore tooth marks (Blumenschine et al.,1996), and are present but less common in trampling marks


(Domínguez-Rodrigo et al., 2009). One of the long cuts (mark A2)has an embedded rock fragment determined by secondary electronimaging (SEI) and energy dispersive X-ray (EDX) to be volcanic andits originwas interpreted to result from impact during the butcheryphase. Such embedded rock fragments are common in chop andpercussions marks. Thus, the argument was made from the com-bined evidence of embedded rock fragments andmarkmorphologydetermined by expert knowledge deployed with reference to themorphologies of experimental (known agent) and inferred (fossil)marks. It is not contested that the damage is ancient, i.e. that itoccurred before the time of fossilization.

Based on published photographs by McPherron et al. (2010),Domínguez-Rodrigo et al. (2010, 2012) alternatively interpretedthe marks from DIK-55 as trampling damage. They also later addedthat the marks do not resemble those made by other possibleagents such as vultures or crocodiles (Domínguez-Rodrigo et al.,2012). Although Domínguez-Rodrigo et al. (2010: 20933) assignall the marks to trampling, they agree that “Marks A1 and A2 onDIK-55e2 are morphologically compelling in their similarity toverified cut marks created by stone tools used in experimentalbutcheries: the marks show deep, V-shaped cross-sections andcontain microstriations. In a less contentious context, the markswould likely be accepted as genuine cut marks”. Thus, althoughtheir argument is also largely based on the morphologies of themarks, they believe the context of the finds makes it difficult toaccept them as butchery marks “because of their singularity andbecause of the inferred age of the fossils” (Domínguez-Rodrigoet al., 2010: 20933). Although the age of the fossils is a less rele-vant point now that flaked stone tools have been reported that dateto 3.3 Ma (Harmand et al., 2015), no other marked fossils as old asthe Dikika marks have since been reported.

McPherron et al. (2011) noted that the main source of contro-versy is not over the morphology of the marks, but instead over theimplications the finds would have for australopith tool use and diet.Domínguez-Rodrigo et al. (2011, 2012) responded that it is inter-pretation of the individual specimens that is at issue, and thattrampling damage should be the null hypothesis for themarks fromDIK-55. We argue here that an insufficient sample of bone surfacemodifications has been studied from deposits dating to this timeperiod to determine if the DIK-55 marks are indeed singular, andwe use a large sample of other marks from the Hadar Formation atDikika to provide a first step toward achieving that quantification.

2.3. Theoretical and methodological problems

The paleoenvironment of Australopithecus spp. can be recon-structed to a certain degree, but as parts of an extinct ecosystem it isdifficult to understand the specific roles and behaviors of austral-opiths if we use only the modern analogs we have at hand. Re-searchers must be able to imagine and test scenarios that do notexist in the present day, and thus ambiguities in the DIK-55 marksmay be attributable to combinations of behaviors and effectors thathave no modern example (Thompson et al., 2011). Once such sce-narios are imagined, in most cases we should be able to designmodel systems to simulate those processes to meet the stringentcasual chain demanded by actualistic studies (Gifford-Gonzales,1991). In addition to potentially taking a different form, evidenceof the earliest butchery behavior is also not likely to be commonlyencountered. This is because the behavior may initially have beenso rare as to be effectively invisible in the archaeological record e

much as is predicted to be the case for the earliest flaked stone tools(Panger et al., 2002). As a related point, rarity of archaeologicalencounters does not in and of itself provide evidence for lack of abehavior, particularly if that behavior is subject to taphonomic bias,



spread over long time spans, and with a wide potential geographicdistribution (Surovell and Grund, 2012).

Domínguez-Rodrigo et al. (2012) performed experiments withunmodified stones to assess if the DIK-55 marks resemble marksmade with unflaked stone. They maintained that the producedrange of variability in mark morphology was too great to reliablyassign any assemblage or individual subset of marks to them.Therefore, in their estimation, trampling must remain the nullhypothesis because it can be more easily discerned from butcherydamage. This approach not only excludes the possibility of identi-fying an entire class of potentially significant ancestral behaviors(unmodified stone tool use), but it has been inconsistently appliedto the zooarchaeological record. Domínguez-Rodrigo et al. (2011,2012) did not consider that trampling should be a null hypothesisfor the next-oldest purported butchery marks from Gona, Ethiopia(at 2.6 Ma), because some of those specimens were found in situ indeposits comprising finer silt and clay particles that also containstone tools. At other Plio-Pleistocene localities such as Bouri, also inEthiopia, ex situ finds with purported butchery marks are notcontested because although they are not associated with stonetools they date to a time when stone tools have been found else-where (de Heinzelin et al., 1999). This returns the argument back toa contextual one, rather than a morphological one, and illustrateshow the field of taphonomy would be well-served by developingmore consensus and standardization on the role of context in thediagnosis of bone surface modifications (Njau, 2012; James andThompson, 2015).

We test trampling as the null hypothesis by quantifying: 1) howmany other fossils recovered from the Hadar Formation at Dikikashow marks with morphology similar to the contested DIK-55marks; 2) how the morphologies of marks from a large sample ofsieved fossils (e.g. a collection unbiased by paleontological selec-tion) compares to the contested marks; and 3) how the character-istics from the DIK-55 marks compare to other marks from Dikikafossils inferred to be trampling marks, as well as to known tram-pling marks from published experimental assemblages. We alsoemploy a comprehensive taphonomic analysis to explore the po-tential for bone surface modification in Pliocene deposits to provideinformation about the broader taphonomic contexts of finds suchas those from DIK-55, and to aid in the reconstruction of time-averaged but distinctive habitats across the paleolandscape.

Although much informative work has been done with analysesof skeletal element representation and fragmentation (Alemseged,2003; Su and Harrison, 2008; Behrensmeyer and Reed, 2013),taphonomic analyses of fossils from landscapes of this age aretypically not based on complete assemblages of all bones recoveredfrom samples of sieved sediments, but are restricted to relativelycomplete and/or diagnostic fossils that are useful for taxonomic

Table 1Description of the criteria a fossil must meet in order to be collected under Protocol 1 o

Protocol number

1 Primates regardless of preservationAll mammalian cranial elements identifiAll horn core and ossicone fragmentsAll mammalian isolated teeth at least haAll complete crocodilian teeth in a bulkFish, crocodile, or turtle crania that are rAll astragali at least half completeAll calcaneus, scapula, humerus, radius,bone e except Elephantidae and HippopLizard or snake vertebraeMake observations on anything left behi

2 Everything collected under Protocol 1Any long bone with at least 1 articular s


identification, ecomorphological analysis, or description/curationof rarely-preserved taxa (including hominins). Table 1 shows thetypical paleontological collecting protocols within the DikikaProject Area, with specific criteria for completeness. This collectingstrategy is problematic for bone surface modification studiesbecause bones or bone portions that are not taxonomically diag-nostic, such as long bone midshaft fragments and ribs, can be someof the most informative for understanding the interactions ofdifferent bone-modifying agents (Pante et al., 2012). Detailed siteformation processes are also difficult to reconstruct from selecteddatasets, although some taphonomic patterning in variables suchas skeletal part preservation or overall bone integrity is stilldiscernible at different environmental, spatial, and temporal scales.We therefore propose that the broader value of this study is that itis the first to include detailed taphonomic work (including bonesurface modification work) across sieved samples of sedimenttaken from open-air localities in Pliocene hominin-bearing de-posits. This augments sedimentological data used to infer deposi-tional environments, and allows for more nuance in reconstructinghabitat assemblages at specific localities that may have presenteddifferent foraging opportunities for australopiths.

2.4. Dikika Research Project area description and depositionalcontext

The DRP area is located in the Lower Awash Valley (Ethiopia). Itis bordered on the north by Gona, Hadar, and Ledi-Geraru and onthe south by the Middle Awash research areas (Fig. 1). Work in theDRP area began in 1999 and has focused on survey in the Hadar(>3.8e2.9 Ma) and Busidima (2.7e0.15 Ma) Formations. In additionto the reported discovery of Pliocene-aged fossils bearing butcherymarks (McPherron et al., 2010), the work has resulted in the dis-covery of a diverse and well preserved fauna, the discovery ofseveral hominin fossils including a nearly complete juvenile Au.afarensis (DIK-1-1; Alemseged et al., 2006; Wynn et al., 2006), theonly known hominin from the Basal Member of the Hadar For-mation (Alemseged et al., 2005), and a complete geologicaldescription of the hominin-bearing Hadar Formation (Wynn et al.,2008).

The lower contact of the Hadar Formation disconformablyoverlies an eroded and weathered surface of the Dahla Series Ba-salts, while its upper boundary is defined by an angular uncon-formity to the overlying Busidima Formation (Wynn et al., 2008).The Hadar Formation contains four tephras which provide directage information (Walter, 1981; Campisano and Feibel, 2008), threeof which further divide the formation into stratigraphic members(from bottom to top: Basal, Sidi Hakoma, Denen Dora and KadaHadar Members). In bulk, the sediments of the Hadar Formation

r Protocol 2.

Description

able to family e except Elephantidae and Hippopotamidae, which are recorded

lf preservedsample for each localityelatively complete

ulna, femur, tibia, fibula, and metapodial fragments at least 3/4 of the completeotamidae

nd (crocodile, turtle, fish, uncollected long bone fragments identifiable to family)

urface



represent the ancient deposits of Lake Hadar, a large persistent lakebasin that had its depocenter northeast of Dikika (Campisano andFeibel, 2008; Wynn et al., 2008). Thus, during times of high lakelevels widespread laminated clays and diatomites were deposited,such as those which characterize much of the deposition of theBasal Member and Denen Dora Members. Meanwhile, duringrelative lake lowstands, the shallow lake and delta clays weresubject to soil formation on low-gradient mudflats and distributaryriver channels that traversed through the swampy delta plains priorto terminating at the lake's shoreline (Aronson and Taieb, 1981;Campisano and Feibel, 2008; Wynn et al., 2008). With this big-picture view of depositional environments in mind, one canrepresent individual exposures of the Hadar Formation as from arange of depositional settings including permanent lake,meandering fluvial channels and their floodplains, distributarydelta channels and their delta plains with swamps, and shallow-gradient soils (vertisols) in the mudflats.

3. Materials and methods

3.1. Field methods

Collection protocols for general paleontological purposesfocused on specimens that were at least ¾ complete, and whichhave been shown to offer information about taxonomic abun-dances or the ecomorphology of members of the fossil community(Plummer and Bishop, 1994). Collecting Protocols 1 and 2 aredescribed in Table 1. For the present study, a new Protocol was alsoestablished and used. This “Protocol 3” is also referred to here as the“circle collections”. The majority of fossil finds in the DRP area aresurface finds and it is useful to understand the taphonomic pro-cesses in operation on such specimens, without restricting analysisto any particular sedimentary context. Using Protocol 3, six sampleswere collected from two different stratigraphic intervals of the SidiHakoma Member (DIK-41-170, DIK-42-23, DIK-43-52, DIK-48-26,DIK-49-13, and DIK-50-50), and one was collected from an inter-val of the Basal Member (DIK-58-20) of the Hadar Formation.Beyond this, the specific locations were chosen at random. Theseare illustrated in Figure 2, and Table 2 provides a summary of theirsedimentological characteristics. Note that localities DIK-49 andDIK-50 cluster together stratigraphically in comparison to the otherSidi Hakoma Member localities.

Once a general locality was selected for sampling, the collectorrandomly tossed a marker onto the ground behind them. Thisprovided the center point for the collection area, which wasmeasured as a circle with a radius of 3 m. All surface finds werecollected using Protocol 1 and then the top 2e3 cm of loose sedi-ments within this circle were sieved through a 5 mm mesh and allfossil fragments were collected. No excavation into the intact sed-iments below was undertaken. Thus, each collection area includedall the fossils within an area of ca. 28 m2 and to a maximum ofapproximately 3 cm depth. The recovered fossils are considered tobe time-averaged samples of what would be found in the deposi-tional environments represented in the exposed sections at eachlocality and summarized in Table 2, and not necessarily related towhat would be found in underlying sediments. Once in the labo-ratory, all fragments were washed in clean water and all specimens>5 mm in the maximum dimension were analyzed.

3.2. Data collection and analytical methods

Data were collected and analyzed in order to achieve thefollowing aims:


1) Provide a description of the taxonomic and skeletal part abun-dances found in assemblages that were not selected only fortheir taxonomic or ecomorphological utility;

2) Describe the sedimentological features of deposits containingthe circle collections;

3) Describe the range of taphonomic modifications to bones acrossthe DRP area;

4) Characterize the post-depositional histories of fossils fromdifferent localities;

5) Characterize the peri-depositional histories of fossils (i.e., whatagents interacted with them when they were in a nutritivestate);

6) Provide an assessment of the attributes of the modifications onthe DIK-55 specimens relative to other modifications foundacross the DRP area.

Laboratory analysis included two phases: basic examination ofthe surfaces of all non-hominin fossils collected from the DRP areaunder Protocols 1 and 2 and curated in the National Museum ofEthiopia, and detailed study and recording of all specimensrecovered from the seven circle collections. All specimens were firstsubjected to microscopic scrutiny under a 10e20� hand lens withbright incident light shining obliquely across the surface. Thisenabled a qualitative overview of whether any specimens exhibitedsurface modification resembling those from DIK-55. The processsimulated the means by which the two modified specimens fromDIK-55 were recovered and initially identified, in that their surfaceswere inspected and diagnosed using an expert knowledgeapproach by an analyst familiar with both experimental and fossilbone surface modifications. In total, 1086 bones were examined inthis way. This procedure allowed for examination of bone surfacesfrom larger and more complete specimens recovered from 113 lo-calities at Dikika, as well as an overviewof whatmorphologies bonemodifications exhibited across a range of depositional environ-ments found in the Hadar Formation of the DRP area.

The second phase of analysis focused on the circle collections(collection Protocol 3), where samples of all bone fragments largerthan 5 mm in the maximum dimension could be assessed. Thisallowed quantification of taxonomic and skeletal element repre-sentation within assemblages that did not comprise specimensselected only for their completeness or taxonomic utility. It alsoprovided the basis for assessing how commonly marks of differentmorphologies and sizes occurred within these assemblages. Allspecimens were examined under a 10e40� binocular zoom mi-croscope with bright incident light from an illuminator shiningobliquely across the surface. This is one procedure that has beenshown to maximize the ability to locate and describe bone surfacemodifications (Blumenschine et al., 1996).

Specimens were subjected to brief refitting to understand thepotential for over-representation of taxa because of single highlyfragmented elements. Specimens were then coded according toskeletal part and lowest possible taxonomic affinity. Mammalianspecimens were given individual records in the database if theycould be identified to specific skeletal part or if they exhibited anysurface modification that could be discerned under low-poweredmicroscopy. Reptile and fish remains were given individual re-cords if they exhibited any surface modification, but detailedtaxonomic or skeletal part assignation will be conducted by therelevant specialist in a future study. All remaining specimens werebulk-recorded according to a series of summary taphonomic attri-butes presented in Table 3. The total studied number of identifiedspecimens (NISP) from the circle collections including both bulk-collected and individually-collected data was 2926.

For the Dikika fossils, each individual surface modification wasgiven its own record. In an effort to produce an objective method


Figure 2. Detailed map of study area showing geographic locations of circle collections.


for recording marks, Domínguez-Rodrigo et al. (2009) introduced aprotocol for differentiating experimentally produced tramplingmarks from cut marks based on multivariate analysis of sixteenmark attributes, fourteen of which are based on categorical vari-ables, one on a discrete variable, and one on a continuous variable.Linear marks (defined as marks with a length:breadth ratio � 2)were coded from the Dikika specimens according to all the attri-butes advocated by Domínguez-Rodrigo et al. (2009). This allowedfor a descriptive evaluation of the frequency with which marksoccur in these deposits that resemble those found on the two DIK-55 specimens, as well as direct comparison to published experi-mental cutting and trampling data. Amorphous marks (defined asmarks with a length:breadth ratio < 2) were coded using thecriteria described in Table 4. Marks with components that had both


morphologies were coded under both systems (e.g. a mark with apuncture and a trailing score from it).

Marks were also assigned a qualitative assessment of the agentto which it would be diagnosed under a more traditional expert-knowledge approach to mark identification. For example, if theirmorphology was that of a tooth mark, percussionmark, or cut markas defined by Blumenschine et al. (1996), or if they had tramplemark morphology as described by Behrensmeyer et al. (1986) thenthis was noted. Individual mark records were not created for marksthat had morphologies resembling fungal etching (Domínguez-Rodrigo and Barba, 2007), insect etching (Backwell et al., 2012),or other forms of bioerosion such as root etchings (Fisher,1995), buttheir presence was noted for each specimen. It was also noted atwhat level of confidence (e.g. high or medium) each mark would


Table 2Location of circle collections and DIK-55, the stratigraphic location of fossils, sedimentological features, and interpretation of depositional environments represented.

Locality Location Position Stratigraphic description of potentialfossil-bearing sediments

Sedimentological description Interpretation of depositionalenvironments represented

58 Lebalahale Basal Mb. Short section just above weatheredupper surface of DSB. Most fossilsderive from zeolitiferous greenegraysands at the extreme base of the BasalMember.

Massive to cross-bedded, poorly sorted,subangular, juvenile litharenitic sandswith average grain size 1e24. Scour andfill structures with lower surfaces sharpand erosional contacts.

Ephemeral streams with shallow, flashyflow locally redepositing juvenilesediment deriving from weatheredsurfaces of basalt.

55 Andedo lower SH Mb. Locality exposes only sedimentsbetween SHT & SH-lm. Many fossils arefound bl SHT. In most cases, anunconsolidated gray sand ~3 m ab SHTappears to produce most fossils,especially those with especially cleansurfaces (no adhering matrix which iscommonly observed on fossils fromDIK-1 sands). Gastropod-bearing sands(B-g), and other sands below the SHTmay produce some of the specimensfound below the SHT.

Sequence of weakly bedded to massiveclays, limestones containing fish scalesand plant fragments as well as adiatomaceous bed. Unconsolidated graysands is massive and poorly sorted withaverage grain size 1e24 (mediumgrained), with particles that range fromfine sand to fine gravel (3 to �34). Thinbeds containing well-rounded gravelclasts form lag deposits at the base oferosional scours.

Shallow lake, muddy shoreline, andsheetwash sand deposits whichprotrude into lake produce most fossils.

41,42,43 Andedo lower SH Mb. Predominantly sediments between SHT& SH-lm. Several local ridges expose upto DIK-1A sand, and some fossils mayderive from above this unit. Manyfossils are found below SHT, but are stilllikely to derive from the SH Memberbased on circumstantial stratigraphicevidence. Unconsolidated gray sand~3 m above SHT appears to producemost fossils, has produced fossils in situ,and preserves many with especiallyclean surfaces (no adhering matrixwhich is commonly observed on fossilsfrom DIK-1 sands).

Sequence of weakly bedded to massiveclays, limestones containing fish scalesand plant fragments as well as adiatomaceous bed. Unconsolidated graysands as in locality 55. Some parts oflocality may contain medium-grained,subangular, consolidated sand withtrough cross-bedding from uppermostsection (see description of locality 49e50 for detailed description).

Shallow lake, muddy shoreline, andsheetwash sand deposits whichprotrude into lake produce most fossils.Some parts of locality may containdistributary delta plain deposits.

48 Andedo lower SH Mb. Predominantly sediments between SHT& SH-lm. Several local ridges expose upto DIK-1A sand, and some fossils mayderive from this unit. Many fossils arefound bl SHT. In most cases, anunconsolidated gray sand ~3 m ab SHTappears to produce most fossils,especially those with especially cleansurfaces (no adhering matrix which iscommonly observed on fossils fromDIK-1 sands). However, it is clear thatgastropod-bearing sands (B-g), andother sands below the SHT mayproduce some of the specimens foundbelow the SHT. A local fault with 3 moffset cuts through the locality.

Sequence of weakly bedded to massiveclays, limestones containing fish scalesand plant fragments as well as adiatomaceous bed. Unconsolidated graysands as in locality 55.

Shallow lake, muddy shoreline, andsheetwash sand deposits whichprotrude into lake produce most fossils.

49 Andedo mid SH Mb. Similar section to that at DIK-1 (Wynnet al., 2006); locality exposes frombelow DIK-1A sand to above DIK-1B.Most fossils, however, likely derivefrom one of the two sands, or thinintervening sand units. Fossils arecemented with carbonate cementedmatrix, and often distorted by post-burial fracture & cementation.

Sequence of cumulative moderate toweakly developed black Vertisols withabundant discrete carbonate nodules.At least two distinct, extensive, tabular,cemented sand bodies are medium- tocoarse-grained (0e24), subroundedwith 5e25 cm scale trough cross-setsand occasional vertical calcareousrhizoliths.

Distributary delta channel & associatedmudflat paleosols (Vertisols) of deltaplains. Fossils attributed to distributarydelta sands.

50 Andedo mid SH Mb. Locality exposes between DIK-1A andDIK-1B sands. Distinct gravel lag at thebase of trough cross sets produceflagstones of conglomerate (grit) ofDIK-1B sand. All fossils presumed toderive from between DIK-1A andDIK-1B sands.

Sequence of cumulative moderate toweakly developed black Vertisols withabundant discrete carbonate nodules.At least two distinct, extensive, tabular,cemented sand bodies are medium- tocoarse-grained (0e24), subroundedwith 5e25 cm scale trough cross-setsand occasional vertical calcareousrhizoliths.

Distributary delta channel & associatedmudflat paleosols (Vertisols) of deltaplains. Fossils attributed to distributarydelta sands.


have been ascribed to that agent if the diagnosis was based purelyon morphological criteria. In previous work, only high-confidencemarks have been published for zooarchaeological assemblages,while medium-confidence marks provide additional data about theclosest morphological match to other marks in an assemblage


(Marean et al., 2000; Thompson, 2010; Thompson andHenshilwood, 2011). These definitions were also employed here.Different cut mark and tooth mark morphologies were described interms of their general shape (Table 4), again to simulate a scenarioinwhich the diagnosis was based purely on morphological grounds


Table 3Attributes used for bulk recording of taphonomic processes on unmarked and undiagnostic specimens in this study.

Attribute Variables

Taxon Mammal, fish, crocodile, turtle/tortoise or more specific where possibleFragment type Non-ID, enamel fragment, tusk fragment, or more specific where possibleFragment size class 0.5e0.9 cm, 1.0e1.9 cm, and 1 cm increments up to �10 cmRecent break present Yes/noWeathering stage 0e5 following Behrensmeyer (1978)Rounding stage 0 ¼ no evidence of rounding; 1 ¼ some edge rounding; 2 ¼ moderate edge rounding; 3 ¼ rounding apparent across entire fragmentNotes Any relevant notes specific to the entry


rather than a combination of morphological and contextualgrounds, as advocated by Blumenschine et al. (1996).

Because Domínguez-Rodrigo et al. (2009) only described theattributes of marks they could see with the naked eye, a note wasmade if each mark on the Dikika specimens was visible withoutmagnification or not. The total number of recorded marks was 482from 256 marked specimens. Statistical tests were all performedusing the software PAST, and included the ManneWhitney U test toassess pairwise differences in the median values of two pop-ulations, the KruskaleWallis test to determine if a series of medianvalues differed significantly across several populations, the Chi-squared test to determine if there were significant differences

Table 4Attributes used to record marks.

Attribute Character state

Cut mark morphology(adapted from the programdescribed in Abe et al., 2002and from Blumenschineet al., 1996)

Cut Incision perpendSlice Incision at angleShave Small curls of boScrape Broad, shallow fi

Puncture Cortical surfacePuncture þ Drag Cortical surfaceChop Short, deep cutSaw Multiple striae o

Tooth mark morphology(adapted from Njau andBlumenschine, 2006)

Pit Bone surface is pScore Bone surface haPit þ score A score emanatePuncture The cortical bonPuncture þ score The cortical bonStar puncture The cortical bonTriangular score A score begins wHook A score traces aBisected pit The pit has been

Total number of damagepatches

Integer � 1 Total number of

Number of small pits withinthe main mark

Integer � 1 Number of discr

Location of microstriationsrelative to main mark

Inside only Microstriations oOutside only Microstriations o

associated damaEmanating Microstriations aInside and outside Microstriations pAbsent No microstriatio

Location of main mark Element edge Main mark occuAt crack Main mark occuFracture edge Main mark occuIn notch Main mark occuIsolated Main mark is iso

Maximum length of main mark To nearest 0.1 mm Measured usingMaximum breadth of main mark To nearest 0.1 mm Measured usingMain mark damage type

(as many as apply)Pit Shape is roundGouge Shape is oval anDivot Bone has been dMicrostriation patch Microstriations oCrushing Bone is crushedDelamination Bone is peelingDisplacement Bone is displaceCompaction Bone is displace

Bruising Yes or No Bone has been d


between the distributions of data between two populations,Fisher's exact test to assess differences between two proportions(in a two-by-two distribution table), and Spearman's rho to deter-mine if two variables correlated with one another (Hammer et al.,2001).

4. Results

4.1. Paleontological collections

Some data on the taxonomic composition of the Sidi Hakomaand Basal Members based on paleontological collecting from the

Description

icular to the bone surfaceto bone surfacene peeling away from a sliceelds often with dimplinghas been breachedhas been breached and a linear mark emanates from the puncture

ccurring in a patchitted downward in a round depression

s been removed in a linear, U-shaped marks from a pite surface is completely breachede surface is completely breached and a score emanates from the puncturee surface is completely breached and the puncture is bisectedith a triangle shape and ends in a long tailhook-shaped trajectorybisecteddiscrete areas of damage that occur within 2 mm of one another

ete pits within the main mark (e.g. largest mark)

nly present within the boundaries of the main marknly present outside the boundaries of the main mark (within up to 2 mm of anyge patch)re continuous between inside and outside the boundaries of the main markresent both inside and outside the boundaries of the main markns observedrs at edge of a complete element portion, for example the rim of a carpalrs within 1 mm of a crack in the boners within 1 mm of the edge of a fracturers within 1 mm of a notch on a fracture edgelated at least 1 mm away from any fragment portion described abovecalliperscallipers

d has one end deeper than the otherisplaced in a circle around a pointccur in a patchand characterized by micro-crackingawayd horizontally with no apparent shaped vertically with no apparent shapeiscolored with an origin point at the main mark



DRP area have been presented elsewhere (Alemseged et al., 2005;Wynn et al., 2006; McPherron et al., 2010). Specimens collectedusing Protocols 1 and 2 were scrutinized to provide a generaloverview of surface modifications across the DRP area. Thisrevealed several types of marks, including large bisected pits andpunctures typical of crocodile damage (Njau and Blumenschine,2006; Baquedano et al., 2012), smaller pits and scores moretypical of mammalian carnivore tooth marks (Blumenschine andSelvaggio, 1988; Blumenschine et al., 1996), dendritic etchingsindicative of root, microbial, or fungal activity (Fisher, 1995;Thompson, 2005; Domínguez-Rodrigo and Barba, 2006), shallowand wandering striae typical of trampling damage (Behrensmeyeret al., 1986; Domínguez-Rodrigo et al., 2009), and a range of othermodifications such as cracking and exfoliation suggestive of sub-aerial exposure (Behrensmeyer, 1978), and matrix invasion ofcracks that likely propagated in situ from sediment pressure (Villaand Mahieu, 1991). Representative images of notable modificationsare provided in Figure 3.

Apart from the two originally described DIK-55 fossils(McPherron et al., 2010), no specimens from any locality in the DRParea had surface modifications that had attributes describable asstone tool butchery marks. None of the surface marks in theremainder of the paleontological collections was characterized by acombination of V-shaped cross-sections, straight trajectories,shoulder effects, sub-parallel microstriations both internally withina groove and as a shoulder effect alongside a main groove(Domínguez-Rodrigo et al., 2009), pitting in association with in-ternal and external microstriations (Pickering and Egeland, 2006),

Figure 3. Representative images of surface modifications across the DRP area: (aec) punctudamage; (dee) scratches considered diagnostic of trample damage; (f) parallel grooves diagof mammalian tooth damage, but overlapping in morphology with experimental crocodile


or any of these suites of characteristics on parts of the bones thatshow anatomical placements indicative of flesh removal or marrowextraction (Bunn and Stanford, 2001). Some specimens did showmarks with some of these features, but never all in the same markand usually occurring near modification more typical of non-human agents such as abrading sediments, crocodiles, ormammalian carnivores (Figure 4).

4.2. Circle collections

The taxonomic and skeletal element representation of the circlecollections is provided in Table 5. They represent a diverse verte-brate fauna comprising small and large mammals, small and largereptiles, fish, and birds e as well as one freshwater mollusk. Cop-rolites were present in DIK-41, DIK-42, DIK-43, and DIK-58. Themajority of all specimens could be classified as aquatic in theirhabitat preferences and 35% of all recovered specimens were fish.Although the fish taxa and skeletal element abundances were notspecifically quantified, the majority of identified specimens werefragments of cranial armor rather than individual diagnosticspecimens. This suggests a high degree of fragmentation ratherthan a large minimum number of individuals. Both aquatic turtlesand land tortoises were present. Although generally the two typesof chelonians could not be distinguished based on small fragmentsof carapace and plastron, 88% of those that could be identified wereaquatic turtles with carapace patterning typical of the familyPelomedusidae.

res, linear marks, and check marks (respectively), all considered diagnostic of crocodilenostic of rodent gnawing; (g) gastric etching; (hei) carnivore tooth marks more typicaldamage.


Figure 4. Examples of marks with some ambiguous features: (a) subparallel incisions with V-shaped cross-sections and abundant microstriations on a mammal long bone, which istypical of cut and percussion damage but which in this case is inferred to be crocodile damage from the associated puncture and sharp “jag” to the bottom left; (b) subparallel lineson a fish element that superficially resemble cut marks but which are too shallow and broad to interpret as “high confidence”; (c) bifurcated V-shaped mark on a mammal ribfragment that under high magnification shows a “tearing away” of the mark walls in a way more typical of tooth damage.


Only 5% of all specimens by NISP were identified as crocodile,although in many cases highly fragmented chunks of bones fromlarge animals could not be easily separated into either mammal orreptile. Thus, crocodile specimens comprised 16% of all specimensthat could be identified as either large mammal or crocodile.Amongst mammals, 61% of all specimens identifiable to the familylevel or belowwere fromHippopotamidae. This number is likely anoverestimate because of a large number of fragments from a singleinnominate from DIK-43 that was inferred to conjoin. The same islikely true for elephants, which were represented by a series ofenamel fragments from a single locality (DIK-58). Bovids comprised41% of the identifiable mammal specimens that were not hippo-potamuses, but these could generally not be identified to the triballevel or below. The single specimen that could be identified to thegenus level (Damalborea) was from the tribe Alcelaphini, modernrepresentatives of which prefer semi-arid grasslands. Thirteen


specimens assigned to Suidae and one to Equidae also support thepresence of some local grassland, but sample sizes of identifiabletaxa were too small to distinguish between localities. The relativerepresentation of aquatic fauna is likely to be useful in categorizinglocalities according to their depositional characteristics, but theProtocol 3 collecting strategy must be paired with Protocols 1 and 2if a larger sample of more specific taxonomic abundance data isdesired.

Long bone breakage patterns can inform if most fragmentationin an assemblage took place while the bone was in a fresh (nutri-tive) state or a dry (non-nutritive) state (Villa and Mahieu, 1991).Unfortunately, there were insufficient numbers of long bones in theDikika assemblages to assess fragmentation in this way. The degreetowhich bones were broken after becoming fossilized, likely duringtheir recent exposure history, could be assessed through exami-nation of fracture edges of all bones. This is relevant for


Table 5Number of Identified Specimens (NISP) in each sample. Shading indicates fragments identified to the same family level listed immediately above it.

Phylum Class Order Family Fragment Type DIK-41 DIK-42 DIK-43 DIK-48 DIK-49 DIK-50 DIK-58 Total

UMa Mb UM M UM M UM M UM M UM M UM M

Mollusca Not determined Not determined Not determined Complete 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1Chordata Osteichthyes Not determined Not determined Not determined 105 2 205 34 309 12 54 7 19 0 26 8 212 35 1028

Reptilia Testudines Pelomedusidae Marginal 0 0 6 0 0 0 0 0 0 0 0 0 0 0 6

Xiphiplastron 0 0 0 1 0 0 0 0 0 0 0 0 0 0 1Carapace/Plastron 1 0 18 7 0 0 2 0 0 0 0 0 0 0 28

Testudinidae Marginal 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1

Carapace/Plastron 1 0 0 0 0 0 2 0 0 0 0 0 0 1 4Testudinidae/Pelomedusidae

Ilium 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1

Limb Fragment 0 0 2 0 0 0 0 0 0 0 0 1 1 0 4Vertebra 0 0 1 0 0 0 0 0 0 0 1 0 1 0 3Neural 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1Costal 0 0 0 0 3 0 0 0 0 0 0 0 0 0 3Marginal 0 0 0 0 1 0 0 0 0 0 1 0 0 0 2Hyo/Hypoplastron 0 0 0 0 0 0 0 0 0 0 0 1 0 0 1Xiphiplastron 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1Carapace/Plastron 13 3 0 0 7 4 0 0 1 0 6 10 77 12 133

Crocodilia Not determined Cranial 0 0 0 0 29 5 0 0 0 0 0 0 0 0 34

Mandible 0 0 0 0 0 3 0 0 0 0 0 0 0 0 3Dental 1 0 2 0 50 0 0 0 0 0 1 0 38 0 92Scute 1 0 1 0 2 0 0 0 0 0 1 0 9 0 14Other 2 0 0 0 13 1 0 0 0 0 0 0 0 0 16

Aves Not determined Not determined Long Bone 0 0 1 0 0 0 0 0 0 0 0 0 0 1 2Mammalia(>4 kg fossil)

Proboscidea Elephantidae Dental 0 0 0 0 0 0 0 0 0 0 0 0 23 0 23

Carnivora/Primates Not determined Metapodial 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1Primates Cercopithecidae Dental 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1Artiodactyla Bovidae Horn Core 0 0 0 0 2 0 3 0 3 0 1 1 3 0 13

Dental 4 0 0 0 1 0 0 0 1 0 1 0 1 0 8Humerus 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1Metapodial 0 0 0 1 2 0 0 0 0 0 1 0 0 0 4Astragalus 0 0 1 0 0 0 0 0 0 0 0 0 0 0 12nd Phalanx 0 0 0 1 0 0 0 0 0 0 0 0 0 0 1

Equidae Dental 0 0 1 0 0 0 0 0 0 0 0 0 0 0 1Bovidae/Equidae Dental 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1Hippopotamidae Dental 3 0 0 0 5 0 0 0 0 0 0 0 17 0 25

Alveolus þ dental 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1Femur 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1Innominatec 0 0 0 0 54 22 0 0 0 0 0 0 1 0 77Magnum 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1

Suidae Dental 5 0 0 0 1 0 0 0 0 0 0 0 7 0 13Not determined Not determined Cranial 0 1 0 1 0 0 0 0 0 0 0 0 0 0 2

Alveolus 0 0 0 0 0 1 0 0 0 0 0 2 0 0 3Maxilla 0 0 0 1 0 0 0 0 0 0 0 0 0 0 1Dental 2 0 25 0 9 0 3 0 2 0 15 0 129 0 185Tusk* 0 0 0 0 219 0 0 0 0 0 0 0 0 0 219Cervical vertebra 0 0 0 0 6 0 0 0 0 0 0 0 0 0 6Thoracic vertebra 1 0 0 0 2 0 0 0 0 0 0 0 0 0 3Lumbar vertebra 0 0 0 0 3 0 0 0 0 0 0 0 0 0 3Vertebra (indet.) 1 0 0 0 16 4 0 0 0 0 0 0 1 0 22Rib 0 0 0 0 1 1 0 1 1 0 1 2 0 0 7Scapula 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1Humerus 0 0 0 0 0 0 0 0 0 0 1 1 0 0 2Femur 0 0 0 0 0 1 0 0 0 0 1 0 0 0 2Tibia 0 0 0 0 1 0 0 0 0 0 0 0 0 0 1Long Bone 4 0 1 3 1 2 2 0 0 0 6 3 1 0 23Compact Bone 0 0 0 0 0 0 1 0 0 0 0 1 0 0 2Non-ID Cortical 2 2 47 5 0 2 2 0 52 0 4 0 6 0 122Non-ID Spongy 0 0 49 0 0 0 0 0 2 0 0 0 0 0 51

Mammalia(>4 kg recent)

Not determined Not determined Cranial 0 0 0 0 0 0 2 0 0 0 0 0 0 0 2

Vertebra 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1Long Bone 0 0 0 0 0 0 4 0 0 0 0 0 0 0 4Non-ID Cortical 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1

Mammalia (<4 kg) Not determined Not determined Calcaneus 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1

Tibia 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1Mammalia/Aves Not determined Not determined Long Bone 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1Mammalia/Reptilia Not determined Not determined Cranial 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1

Alveolus 0 0 0 0 2 0 0 0 0 0 0 0 1 0 3Mandible 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1

(continued on next page)


Please cite this article in press as: Thompson, J.C., et al., Taphonomy of fossils from the hominin-bearing deposits at Dikika, Ethiopia, Journal ofHuman Evolution (2015), http://dx.doi.org/10.1016/j.jhevol.2015.06.013

Table 5 (continued )

Phylum Class Order Family Fragment Type DIK-41 DIK-42 DIK-43 DIK-48 DIK-49 DIK-50 DIK-58 Total

UMa Mb UM M UM M UM M UM M UM M UM M

Rib 0 0 0 0 1 0 0 0 1 0 0 0 4 0 6Vertebra 1 0 0 0 0 0 0 1 0 0 0 0 1 0 3Non-ID Cortical 18 2 2 3 108 16 19 0 0 0 47 6 150 11 382Non-ID Spongy 16 0 0 0 35 0 6 0 0 0 11 0 234 0 302

Not determined Not determined Not determined Not determined 0 0 10 0 0 0 0 0 0 0 0 0 0 0 10Total 182 11 372 57 883 77 104 9 82 0 127 36 926 60 2926

a Unmarked.b Marked.c Inferred to all conjoin from a single specimen.


understanding the degree to which a given circle collection in-cludes fossils that have been exposed at the surface for differentperiods. Where recent breaks occurred, the break surface had adifferent appearance from the rest of the fossil surface, and lackedadhering matrix wherematrix was present. This could not be easilydetermined for spongy bone fragments, but all data for theremainder of the assemblage are provided in Figure 5, and showsignificant differences between localities (X2 ¼ 340.58; DF ¼ 6;p < 0.0001).

Weathering stage data show that different localities producedfossils with varying exposure histories. Localities can generally begrouped according to whether or not three-quarters or more oftheir fossils fall into the pristine weathering category of Stage 0 or ifthere is a wider range across categories (Fig. 6). The Basal Membercollection from DIK-58 has a clearly bimodal distribution, withnearly 40% of the fossils in the least extreme category of noweathering (Stage 0) and approximately 25% of the fossils in themost extreme category of heavy weathering (Stage 5). Althoughsome elements, such as crocodile scutes, do not weather in com-parableways to other elements, these are so rarely represented thatthey should not affect the weathering data. Of the Sidi HakomaMember samples, DIK-49 had a very high proportion of Stage 5fossils, and DIK-50 had a more even distribution in the laterweathering stages but with the majority still falling in the lowerstages overall.

Fragment sizes were generally small in comparison to thepaleontological collections, with 33% of all fragments less than 2 cmin the maximum dimension (Table 6), and a median fragment sizeclass of 2 (1.0e1.9 cm). There were some significant differencesbetween localities (KruskaleWallis H ¼ 123.7; p < 0.0001). DIK-49and DIK-50 had significantly larger fragment sizes than the othercollections but were indistinguishable from one another (Man-neWhitney U ¼ 5710; p ¼ 0.5577). These two localities also clustertogether stratigraphically, and have different depositional

Figure 5. Recent break data. Fragments with a recent break are labelled “yes” andthose without are labelled “no”. Numbers of fragments are provided within each bar.


environments as inferred by the sedimentology than do the otherSidi HakomaMember localities. The abundance of fish fragments inthe circle collections provide an obvious explanation for why somany fragments are small, but even when fish are removed fromthe analysis themedian size class remains 2, and the same size classpatterning across the collections remains apparent.

The distribution of edge rounding on the fossils differs betweenlocalities (Fig. 7a). Although most localities had some specimensthat fell into the most extreme rounding class (Class 3), localitiessuch as DIK-42 and DIK-43 almost exclusively had specimens inclass 0. The Basal Member locality of DIK-58 had the highest pro-portions of more heavily-rounded specimens, followed closely bythe Sidi HakomaMember localities DIK-49 and DIK-50. Some of theedge rounding datamay be affected by the proportions of fish in the

Figure 6. Weathering stage data: (a) localities where most fragments have been barelyexposed; and (b) localities with more variable exposure histories. Weathering stages0e5 after Behrensmeyer (1978). Numbers in embedded tables represent numbers offragments in each stage at each locality.


Table 6Fragment size classes.

Size class Cm DIK-41 DIK-42 DIK-43 DIK-48 DIK-49 DIK-50 DIK-58

All No Fish All No Fish All No Fish All No Fish All No Fish All No Fish All No Fish

1 0.5e0.9 38 5 152 54 204 54 30 12 9 6 19 7 158 592 1.0e1.9 94 32 182 63 353 242 48 16 26 13 62 45 591 4583 2.0e2.9 42 33 61 47 244 191 21 10 12 10 31 27 172 1604 3.0e3.9 9 7 19 13 79 72 2 2 7 6 23 23 41 385 4.0e4.9 6 5 7 5 34 34 5 5 8 8 9 8 14 146 5.0e5.9 2 2 3 3 21 21 4 4 6 6 8 8 3 37 6.0e6.9 1 1 3 3 11 11 0 0 0 0 6 6 1 18 7.0e7.9 0 0 0 0 2 2 0 0 4 4 2 2 0 09 8.0e8.9 0 0 0 0 4 4 2 2 7 7 1 1 4 410 9.0e9.9 0 0 1 1 2 2 1 1 1 1 0 0 1 111 �10.0 1 1 1 1 6 6 0 0 2 2 2 2 1 1

Figure 7. Proportions of fragments at each locality in various rounding stages, with0 ¼ not rounded, 1 ¼ slight rounding on edges, 2 ¼ rounding compromising theoriginal shape of the fragment, and 3 ¼ original shape of fragment completely lost. (a)includes fish; and (b) does not include fish.



assemblage, as fish bone fragments are generally smaller andharder than mammal bone (Archer and Braun, 2013). When fish areremoved from analysis, the lack of edge rounding at DIK-42 andDIK-43 remains apparent, while the variability in rounding classesat the other localities becomes more prominent (Fig. 7b).

A range of surface modification morphologies were observedwithin the circle collections (Table 7). The maximum number ofmarks on any single specimenwas 24 in one case, although the restof the specimens had between one and nine, with amedian value ofone. Only 256 (8.7%) of all specimens had any mark (includinggeneral microabrasion) on them; 237 of these marks were assignedto an agent with “high confidence (HC)” and the rest were “mediumconfidence (MC)”. Most marks were extremely small. For thosespecimens that could be measured (n ¼ 450; measured as eitherthe maximum length of the main groove for linear marks or themaximum length of the main mark for amorphous marks), themean length was 4.2 mm for linear marks and 2.5 mm for amor-phous marks. However, the two mark types have very differentdistributions in their sizes, with amorphous marks being heavilyleft-skewed and with a median maximum length of 1.7 mm(average area 5.6 mm2 and median area 1.6 mm2), and linear markshaving a roughly normal distribution with a median maximumlength of 3.8 mm. The generally small size of marks is also evi-denced by the fact that only 41% of all recorded marks were visibleto the naked eye. Sixty six percent of the marks had tooth markmorphology (n ¼ 307), and 60% of these were visible to the nakedeye. Eighteen percent of marks were a closest match for tramplingdamage (n ¼ 86) but only 4 (5%) of these were visible to the nakedeye. Patches that did not fit the definition of any known agent andgeneralized microabrasion with no associated mark were the onlyother damage types recorded, and in both cases it was rare for themto be noted without the aid of magnification.

Only three marks had cut mark morphology, and of these onlyone was visible without magnification. The specimen bearing thismark was from DIK-43. Bones at this locality generally had a bril-liant white surface, which made it difficult to discern recent fromancient damage based on color. The mark with cut morphologyappeared most likely to be recent on the basis of its shiny, compactdamage floor relative to the appearance of the remainder of thebone surface. Although the majority of its attributes were similar tocut marks (e.g. a straight microstriation trajectory, flaking on theshoulder, and a narrow V shape), it also had some attributes thatwere more typical of trampling damage (e.g. a sinuous groovetrajectory). Similarly, only six marks had percussion markmorphology and of these again only one (also from DIK-43) couldbe seen without the aid of magnification. It was located near amodern fracture edge and from the slight sheen within the mark italso appeared to be recent in origin (Fig. 8). Across the entire sievedsample, no marks had morphologies that were an excellent match


Table 7General description of marks visible without magnification.

Mark morphology DIK-41 DIK-42 DIK-43 DIK-48 DIK-49 DIK-50 DIK-58 Total

Visible to naked eye? No Yes No Yes No Yes No Yes No Yes No Yes No Yes

Cut Mark 0 0 0 (2)a 0 0 0 (1) 0 0 0 0 0 0 0 0 0 (3)Non-ID Patch 2 0 11 0 3 1 2 0 0 0 3 2 14 1 39Percussion Mark 0 0 0 (2) 0 1 1 0 0 0 0 0 (1) 0 0 (1) 0 2 (4)Tooth Mark 3 24 41 (6) 0 32 (1) 90 (2) 3 8 0 0 3 42 (2) 39 21 306 (11)Trample Mark 3 0 37 (3) 0 1 4 1 0 0 0 14 (1) 0 22 0 82 (4)Microabrasion only 2 0 5 0 11 0 1 0 0 0 9 0 3 0 31Total 10 24 94 (13) 0 48 (1) 96 (3) 7 8 0 0 29 (2) 44 (2) 78 (1) 22 460 (22)

a Numbers in parentheses indicate marks that are medium-confidence only; their morphology most closely resembles the assigned agent but it would not be published as ahigh-confidence mark.

Figure 8. Marks with cut (a) and percussion (b) morphology.


for either cutting or percussion damage, and those that were theclosest matches appeared recent. None was therefore considered“high confidence” under the criteria defined here.

Seventeen percent (n ¼ 80) of all marks were classified as linearonly, while 64% (n ¼ 310) were classified as amorphous only.Thirteen percent (n ¼ 61) had attributes of both, and the remaining6% (n ¼ 31) were only instances of microabrasion with no addi-tional marks on the same specimen. Of the total sample of 2926bones, only 119 (4%) had microabrasion on them, and most cases ofmicroabrasion (94%) were associated with other marks on the samespecimen. Within the tooth mark morphology categories, the ma-jority of marks were not specific to any particular taxonomiccategory, although 9% (n ¼ 29) were characteristic of crocodiledamage (Njau and Blumenschine, 2006; Baquedano et al., 2012).Notably, these did not occur at all localities (Table 8). Marks withinboth morphology classes were generally small (median area forcrocodile damage was 1.17 mm2 and median area for generic toothdamage was 2.49 mm2), and the differences between their median


areas was not significantly different (U ¼ 2154; p ¼ 0.1534).Experimentally-generated crocodile marks appear to be larger thanthose observed on the circle-collected fragments (Njau andBlumenschine, 2006; Baquedano et al., 2012). It is a well-knownphenomenon that as fragment sizes increase, they become morelikely to exhibit marks (Abe et al., 2002); future work with anextended sample of larger specimens will determine if mark sizealso increases with fragment size.

Most toothmarkswere classified as amorphousmarks, althoughsome were scores or gouges and received additional or only datacoding with respect to the portion of the mark that was linear.Characteristics of all amorphous marks are provided in Table 9,along with the same data coding for the two DIK-55 specimens thatwere previously published (McPherron et al., 2010). In 99% of casesvisible to the naked eye, amorphous marks consisted of a singledamage area with no small pits within the damage area. More than95% of those visible without magnification had no microstriations,and most of the ones that did had microstriations constrained to


Table 8Numbers of modifications within different tooth mark morphology categories.

DIK-41 DIK-42 DIK-43 DIK-48 DIK-50 DIK-58 Total

Generic Morphology

Pit 21 17 56 5 20 52 171Pit þ Score 1 3 18 1 2 1 26Puncture 0 2 4 1 3 6 16Puncture þ Score 0 2 1 0 1 0 4Score 5 15 35 0 13 1 69

Total 27 39 114 7 39 60 286

Crocodile Damage

Bisected Pit 0 4 5 1 0 0 10Check 0 0 2 0 0 0 2Hook 0 0 3 0 0 0 3Star Puncture 0 0 1 3 2 0 6Triangular Pit 0 1 0 0 0 0 1Triangular Score 0 1 0 0 6 0 7

Total 0 6 11 4 8 0 29

Table 9Distribution of mark attributes for amorphous marks for the circle collections andDIK-55.

All marks Without Magnification DIK-55a

N % N % N

Total damage areas1 365 98.4% 192 99.0% 72 5 1.3% 2 1.0% 25 1 0.3% 0 0.0% 1

Pits in main markb

0 364 98.1% 191 98.5% 42 2 0.5% 0 0.0% 33 4 1.1% 2 1.0% 14 0 0.0% 0 0.0% 25 1 0.3% 1 0.5% 0

Microstriation locationInside 47 12.7% 7 3.6% 10Outside 0 0.0% 0 0.0% 0Emanating 1 0.3% 1 0.5% 0Inside and outside 4 1.1% 1 0.5% 0Absent 319 86.0% 185 95.4% 0

Location of markAt crack 27 7.3% 18 9.3% 0Element edge 30 8.1% 17 8.8% 0Fracture edge 155 41.8% 85 43.8% 7In notch 2 0.5% 1 0.5% 0Isolated 157 42.3% 73 37.6% 3

Main mark dominant damage typeCompaction 2 0.5% 0 0.0% 4Crushing 4 1.1% 1 0.5% 4Delamination 1 0.3% 0 0.0% 2Displacement 10 2.7% 5 2.6% 0Divot 2 0.5% 0 0.0% 0Gouge 75 20.2% 45 23.2% 0Microstriation patch 47 12.7% 6 3.1% 0Pit 230 62.0% 137 70.6% 0

BruisingPresent 4 1.1% 1 0.5% 0

a Percent is not supplied as the sample size is too small to be meaningful.b This may also include some examples of a single pit present, but merging to

become part of the main mark.


inside themark boundaries only. Marks consisting of microstriationpatches were more commonly observed with the aid of magnifi-cation. Forty-four percent of macroscopically visible amorphousmarks occurred at the fracture edge of a fragment, 38% occurred inan isolated part of the fragment, and most of the remainderoccurred at cracks or at element edges. These are characteristiccontexts of both experimentally observed tooth mark and percus-sion mark damage (Blumenschine et al., 1996).


Domínguez-Rodrigo et al. (2009) showed that within theirexperimental assemblages, five of their 16 proposed characteristicscould be used to differentiate assemblages of marks made bysimple stone flakes versus trampling: trajectory of the main groove,shape of the main groove, presence of microstriations, trajectory ofmicrostriations, and location of microstriations. Shoulder effect andflaking on the shoulder were also considered to be relevant. Theresults of these seven criteria as recorded for the Dikika circlecollections are given in Table 10, along with the same criteriarecorded for the previously published DIK-55 marks (McPherronet al., 2010). Results are provided for marks that can be seen withthe naked eye (to make them comparable to the experimentalsample), and for all marks (to take advantage of the larger samplesize). It is worth bearing in mind that these experimental charac-teristics were designed to differentiate trampling marks from cutmarks, and do not include attributes of other linear marks, such astooth scores. The experimental datasets also do not include per-cussion damage, which can overlap with cutting damage and maycause some differences when being compared to the fossil datasets.

5. Discussion

“Landscape-scale taphonomy” that includes analysis of bonesurface modifications is an approach that has been implemented atEarly Pleistocene deposits that contain flaked stone artifacts(Blumenschine and Peters, 1998; Potts et al., 1999; Domínguez-Rodrigo et al., 2002; Tappen et al., 2002; McCoy, 2009;Blumenschine et al., 2012), but not for sites older than about2 Ma. More broadly, bone surface modification studies of Pliocene-aged fossils are uncommon. Most that have been done in associa-tionwith Australopithecus are from South Africa, at cave sites whererecovery methods are more akin to archaeological recovery(Pickering et al., 2004a; 2004b). The benefit to these analyses is thatthey include more complete assemblages, while a drawback is thatthey represent depositional environments in which australopithremains are preserved, but not places where they habitually lived.

Within deposits of tectonically-driven sedimentary basins, sur-face modification studies have been performed at only a few sitesolder than 2 Ma: Gona (Domínguez-Rodrigo et al., 2005), Bouri (deHeinzelin et al., 1999), and Dikika (McPherron et al., 2010). In thesecases, the focus has been on individual description of specimensbearing marks interpreted to be inflicted by hominin tool use, andfrom specific sites of interest, rather than more complete assem-blages sampled from across the landscape. This approach does notdocument the range of variation and frequency of bone modifica-tions that would appear in fully-recovered assemblages, and makesit impossible to establish if purported butchery marks are unusualin their characteristics relative to the background population. Un-derstanding which marks are unusual in size or shape is especiallygermane to diagnosing trampling damage, which should have beena widespread process that did not discriminate by bone or boneportion.

5.1. Assessment of the trampling argument

Domínguez-Rodrigo et al. (2010, 2011, 2012) exhaustivelycompared images of each DIK-55 mark to experimental markmorphologies and concluded that they are a best fit for tramplingdamage, but then asserted such comparisons cannot be used todiagnose individual marks but could only apply at the level of thetotal mark-sample. This problem is now more visibly exposed asone that requires methodological scrutiny, because diagnosis ofindividual marks is standard in taphonomic research, and is anapproach accepted for Plio-Pleistocene sites such as Gona(Domínguez-Rodrigo et al., 2005) and Bouri (de Heinzelin et al.,


Table 10Distribution of mark attributes for linear marks for published experimental collections (Domínguez-Rodrigo et al., 2009), the circle collections, and DIK-55.

Domínguez-Rodrigo et al. (2009) This study Domínguez-Rodrigo et al. (2009) This study

Trampling Unretouched Retouched Dikika Circles All Dikika Circles Visible DIK-55a Trampling Unretouched Retouched Dikika Circles All Dikika Circles Visible DIK-55

Groove trajectoryStraight 75 230 102 44 14 7 29.8% 93.5% 97.1% 31.2% 34.1% 53.8%Curvy 42 16 0 45 11 6 16.7% 6.5% 0.0% 31.9% 26.8% 46.2%Sinuous 134 0 3 52 16 0 53.4% 0.0% 2.9% 36.9% 39.0% 0.0%

Groove shapeV 10 238 6 56 4 5 4.0% 96.7% 5.7% 39.7% 9.8% 38.5%\_/ 241 8 99 85 37 8 96.0% 3.3% 94.3% 60.3% 90.2% 61.5%

Internal microstriationsPresent 188 190 105 4 2 12 75.0% 77.2% 100.0% 2.8% 4.9% 92.3%Absent 63 56 0 137 39 1 25.0% 22.8% 0.0% 97.2% 95.1% 7.7%

Microstriation trajectoryb

Continous 169 190 105 3 2 12 67.3% 100.0% 100.0% 75.0% 100.0% 100.0%Discontinuous 82 0 0 1 0 0 32.7% 0.0% 0.0% 25.0% 0.0% 0.0%

Location of microstriationsWalls 7 180 3 0 0 0 2.8% 73.2% 2.9% 0.0% 0.0% 0.0%Bottom 219 0 93 3 1 4 87.2% 0.0% 88.6% 75.0% 50.0% 33.3%Both 25 10 9 1 1 8 10.0% 4.1% 8.6% 25.0% 50.0% 66.7%

Shoulder effectPresent 15 81 78 30 4 0 5.9% 32.9% 74.3% 21.3% 9.8% 0.0%Absent 236 165 27 111 37 13 94.1% 67.1% 25.7% 78.7% 90.2% 100.0%

Flaking on shoulderPresent 7 36 54 15 5 5 2.7% 14.6% 51.4% 10.6% 12.2% 38.5%Absent 244 210 51 126 36 8 97.3% 85.4% 48.6% 89.4% 87.8% 61.5%

a This only includes those specimens from DIK-55 that were published with the interpretation that they were butchery-inflicted (McPherron et al., 2010); n¼ 13 because only linear marks were included andmarks DIK-55-3-D, DIK-55-3-H, and DIK-55-2-A have multiple non-overlapping components that were combined in the interpretation of 12 individual butchery actions and these are each coded separately here to match the experimental andcircle collection data.

b Only applicable if microstriations are present.

J.C.Thompson

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1999), at a time when purported butchery damage is also very rare.When discerning the origin of a mark, researchers therefore assigndifferent e and usually unspecified e weightings to the morphol-ogies of bone surface modifications versus the contexts fromwhichthey are recovered (Njau, 2012; James and Thompson, 2015). Thefact that this approach is accepted for Gona and Bouri but contestedat Dikika does not mean that the DIK-55 marks should also beaccepted as butchery damage without scrutiny. It does mean thatthe sum evidence for hominin butchery activities prior to 2 Ma e

and thus their dietary and behavioral significance in homininevolution e cannot be evaluated until the same level of detail inreporting has been applied to all sites.

The issues exposed by the debates surrounding DIK-55 havebroader implications than simply resolving what caused the markson the two specimens reported as hominin-modified. Much workremains at the methodological, theoretical, experimental, andempirical levels. Experimental parameters in zooarchaeologicalresearch are poorly standardized and frequently differ in the bonesubjects that are used, the method of their preparation, and thevariables that are included in the experiments (James andThompson, 2015). Researchers often test quite specific hypotheseswith their experimental assemblages, which may make some ex-periments more applicable to the interpretation of some fossil as-semblages than others (Domínguez-Rodrigo, 2008; Pobiner, 2008).Therefore, although experimental data are extremely useful, intheir current manifestation they are variable in their direct appli-cability to specific fossil assemblages, in their comparability to oneanother, and in their ability to capture the complexity of real pat-terns and processes.

Middle Range approaches (e.g. those that tie present-day ob-servations to the traces they leave and then apply them to tracesleft in the past) are best complemented by data derived directlyfrom the fossil record, and interpretations are strongest when linesof evidence interpretedwithin strict uniformitarian actualistic logicare better contextualized within the range of variation expressedwithin a fossil sample. Our study adds a contextual angle to theinterpretation of the DIK-55 specimens, which acts in complementto experimental and naturalistic research (collectively, “actualism”)that has become a staple for much taphonomic work (Marean,1995). This is necessary because assemblages of fossils have com-plex taphonomic histories and (unlike with modern experimentalsamples) the total-mark sample is likely to contain a range of markscaused by several different agents and may not easily fall intodistinct categories. Although experimental and naturalisticresearch provide essential inferential links between the observablepresent and traces left from past processes, they have severallimitations in their operation. An actualistic study conductedwithin a brief time interval cannot easily replicate slow, long-termprocesses or palimpsests of slow processes that occur over thecourse of fossilization. It also is difficult to replicatemodifications tobone surfaces that are unique to the long-term process of fossil-ization, and this area of research demands that new models bedeveloped to accommodate such processes. Given that the specifictaphonomic pathways within a fossil assemblage will each havetheir own unique combinations of circumstances, it is impossible toexperimentally replicate every possible combination of variablesand scenarios that may have occurred in the past (Domínguez-Rodrigo and Yravedra, 2009). However, as actualistic researchcontinues to build, it is possible to replicate every extant agent,model extinct agents, and then computationally simulate thepossible combinations to determine statistically where the fossilsample best fits (Cleghorn, 2006). The fossil record itself providesclues about the specific agents that should be modelled for specificenvironments.


Experimental and naturalistic work can only be performedwithin modern environments, modern ecosystems, and by modernorganisms (or models of extinct ones), so that the current state ofactualistic research has not equipped researchers with the fullrange of interpretive analogs for reconstructing the range of pro-cesses that operated in the past (Gifford, 1981; Gifford-Gonzales,1991). For example, there were extinct carnivores in the Pliocenethat had unique tooth morphologies that may have created novelmarks that are currently undocumented (Marean and Ehrhardt,1995; Brochu et al., 2010). By joining observations from the fossilrecord to novel actualistic research and statistical modeling, futuretaphonomic studies of Pliocene hominin-bearing deposits will beable to provide even better tools for the interpretation of these pastenvironments.

Here, we began that work through taphonomic analysis of allfossils recovered from the DRP area, including detailed analysis ofthe surfaces of bone from seven assemblages that were recoveredusing sieved collectionmethods and complete analysis of the entirepopulation of marks on them. In addition to a contextual approach,our study also explicitly took a probabilistic stance, in that tram-pling damage should be the null hypothesis for bone modificationat DIK-55 only if similar damage is common across the project areawhere sandy deposits occur. Moreover, where such deposits occur,damage should resemble the DIK-55 specimens in form, size, andfrequency.

Domínguez-Rodrigo et al. (2010, 2011, 2012) maintain thattrampling damage should be the null hypothesis for themarks fromDIK-55 because the specimens are ex situ finds that may havederived from sandy deposits, themarks are morphologically similarto some experimental trampling marks, and the specimens appearto exhibit microabrasion on their surfaces. Here, we address each ofthese arguments and provide a contextual framework using newdata on the morphology of other bone surface modifications fromthe same deposits. First, the argument that DIK-55 finds are ex situdoes not add any evidence for or against the likelihood of tramplingin an abrasive sediment. The stratigraphic association of the twospecimens was originally reconstructed to a sandy deposit based onembedded matrix, with the minimum age of the entire sectionproviding the conservative minimum age for the specimens(McPherron et al., 2010). That sandy sediment may provide a moreabrasive medium than finer sediments, but the fact that the spec-imens are ex situ does not contribute to this argument because thesurface modifications in question were shown to be ancient inorigin. Furthermore, the sandy sediments at DIK-55 contain coarseparticles but the shape of those particles is generally rounded. Theinfluence of particle shape, rather than simply size, is not a nuancethat is captured in any published experimental trampling studies.

The second argument, that the marks on the DIK-55 specimensmorphologically resemble trampling marks, now can be addressedin several ways. Qualitative observations of over 1,000paleontologically-collected specimens of what are predominatelylarge mammal elements, and qualitative and quantitative obser-vations of nearly 3,000 specimens that represent a mixture of el-ements from mammals and other taxa recovered from sievedsediments, show that no other specimens recovered from theHadar Formation in the DRP area exhibit marks that resemble thoseon the DIK-55 specimens. The unusual appearance of the DIK-55specimens was what prompted their initial collection, and thedata show that in both categorical and metric variables they areindeed outliers relative to a large population of marks from a rangeof depositional environments. Further assessment can also now bemade at a population level using the criteria argued by Domínguez-Rodrigo et al. (2009) to differentiate between cut and tramplemarks.



The methodology behind the trampling experiments involvedthe production of cut marks with both retouched and unretouchedflakes, and then the trampling of those same specimens. Cut markswere distinguished from trample marks by indicating them withcolored marker prior to trampling, although confounding effectsmay still have arisen because existing cut marks can be modifiedthrough the trampling process (Behrensmeyer et al., 1986).Domínguez-Rodrigo et al. (2009:2654) note that their criteria are“best applicable in cases of low-intensity trampling”, because “itseems that prolonged exposures to trampling further reduce(rather than increase) the similarities between trampling marksand butchery marks.” Of the original 16 variables that were recor-ded, seven of the categorical variables were found to differentiate,at a population level, between samples of cut marks and samples oftrample marks. Associated microabrasion was not one of these.

Domínguez-Rodrigo et al. (2012) later revised the criteria thatwere useful for differentiating trampling from stone tool butcherydamage by referring to 14 original variables and only four that offersignificant results. They performed further butchery experimentson chicken and sheep bones using unflaked stones and thencompared the resultant marks to experimental trampling marksusing these four variables and an additional four that differentiatedbetween marks made by replica Acheulean handaxes and simpleflakes. Domínguez-Rodrigo et al. (2012) found that there is signif-icant overlap between linear marks caused by trampling and bybutchery with an unmodified stone. For this reason, they counselagainst assigning linear marks of unknown origin to unmodifiedstone as a possible effector. However, if an argument is employedthat the morphology of the DIK-55 marks matches tramplingdamage, and if trampling damage cannot be differentiated fromunmodified stone damage, then the morphologies of the DIK-55marks cannot be logically used to infer one process in preferenceto another. Furthermore, this study has detailed how linear marksare not the dominant form of mark in the Hadar Formation depositsin the DRP area, and in fact most of the marks on the DIK-55specimens are also not linear (or exclusively linear) in form.

Only summary data have been published for the experimentaltrampling and cut mark datasets, which restricts the number andtype of comparative analyses that can be performed. However,where they do occur they are a good match at the assemblage levelfor marks produced through a moderate degree of experimentaltrampling. Although trampling marks are not as common on HadarFormation fossils as modifications with other morphologies(especially tooth marks), only two of the seven criteria thatdistinguish experimental trampling marks from cut marks weresignificantly different in their distributions on the linear circlecollection marks (Table 11). The two significant results occurred in

Table 11Comparison of the distributions of linear mark attributes between published experimen

Circle vs. experiment

Differentiates trampling from simple flake

Groove shape 0.1170Internal microstriations <0.0001Microstriation trajectory 0.0554Location of microstriations n too small for X2

Differentiates trampling from retouched flake

Shoulder effect 0.3200Flaking on shoulder 0.0161Differentiates trampling from both

Groove trajectory X2 ¼ 3.6048;DF ¼ 2; p ¼ 0.1649

a X2 used where comparisons are of a distribution, all other p-values are Fisher's exact cvalues indicate significance below the a ¼ 0.05 level.


attributes that are extremely subtle (presence of microstriationsand shoulder flaking), and which would be expected to occur inlower numbers on fossil collections because they are less resistantto erasure through subsequent taphonomic process.

In contrast, the DIK-55 marks are not a good match for experi-mental trampling damage. Sample sizes were too low to use X2

analysis to compare the distributions of diagnostic mark attributesbetween the DIK-55 specimens and other datasets, but there isstatistical support for the qualitative observation that the DIK-55marks differ on the whole from experimental trampling marksusing Fisher's exact test on basic 2 � 2 comparisons of each attri-bute that was advocated by Domínguez-Rodrigo et al. (2009) todifferentiate trampling from butchery damage (Table 11). The testshowed significant differences between the proportions of attri-butes in the DIK-55 marks and experimental trampling marks infour of the seven criteria, and significant differences between theproportions of attributes in the DIK-55 marks and the rest of thecircle collections in three of the seven criteria (one was not avail-able for testing).

In terms of size, the marks on the DIK-55 specimens were farlarger than marks in the sieved samples from the Hadar Formation.Linear marks from the circle collections that were visible withoutmagnification were on average 5.2 mm long (4.3 mm medianlength), and amorphous marks had an average area of 5.8 mm2

(median area 2.2 mm2). The DIK-55 marks had an averagemaximum length of 7.9 mm (median 6.0 mm) for linear marks andan average area of 37.3 mm2 (median 16.8 mm2) for amorphousmarks e all of which could be seenwithout magnification. That theDIK-55 marks are size outliers in comparison to a large sample of“background” marks is supported by resampling using a permu-tations test with 10,000 iterations on the combined circle and DIK-55 samples. This showed that the probability of drawing a sampleof marks with the mean mark length found on the DIK-55 modifiedbones is p < 0.00. A similar permutation test on mark area alsoyielded a result of p < 0.00 (Fig. 9). Domínguez-Rodrigo et al. (2009)do not provide length data on their trample and cut marks, but themarks they illustrate all appear to be quite small based on thesupplied scale bars. It is also worth noting that all trampling ex-periments to date are focused on the analysis of linear marks, andmany of the DIK-55 specimens have marks that are large andamorphous (or have an amorphous component), and therefore arenot directly comparable in many ways to trampling damage as ithas been documented experimentally to date.

The presence of internal microstriations were once consideredto be key features separating stone tool damage from other sorts ofdamage, such as carnivore tooth damage (Blumenschine et al.,1996), and it is notable that the fossil specimens from the circle

tal collections (Domínguez-Rodrigo et al., 2009), the circle collections, and DIK-55.a

DIK-55 vs. circle DIK-55 vs. experiment

0.0282 0.00030.0001 0.1986N/A 0.02061.0000 <0.0001

0.5618 1.00000.0484 <0.0001

1 0.5487

omparisons of 2� 2 table proportions (e.g. only two variables were present); shaded


Figure 9. Results of resampling (1,000 permutations) for mark length (left) and area (right). Vertical dashed line shows the probability of drawing a mark sample with the samesizes as the DIK-55 specimens from the mark sizes represented in the circle collections.


collections had extremely low incidences of internal micro-striations. This may be the result of post-depositional processesthat erase tiny microfeatures in shallowmarks, such as weathering,smoothing, or even simply the fossilization process (Behrensmeyeret al., 1986; Olsen and Shipman, 1988; Domínguez-Rodrigo et al.,2009). However, both trampling (Domínguez-Rodrigo et al.,2009), and crocodile damage have now specifically been noted toproduce marks with microstriations (Baquedano et al., 2012). Car-nivores may also produce them when they modify bones with gritin their mouths. Taken together, it now seems that the simplepresence of microstriations can be caused by a number of tapho-nomic variables, but that attributes of microstriations such as theirtrajectory, placement, number, or even depth may be shown tobetter separate some of these processes. Further experimentalwork that includes more quantitative means of recording difficultvariables, such as depth, microstriation attributes, and mark cross-section, will be required to better understand this phenomenonand apply it to the fossil record (Bello and Soligo, 2008; Bello et al.,2009; Newman, 2015). This work must be done in light of the factthat fossils with long histories of fossilization and exposure maynot preserve fine features such as microstriations and shoulderflaking with sufficient fidelity at all sites for different localities to becomparable to one another, or to the experimental datasets.

Microabrasion is a process that has been reported to occurexclusively from trampling in comparison to butchery (Domínguez-Rodrigo et al., 2009). However, in spite of samples taken across arange of depositional contexts at Dikika, and in spite of their sur-ficial contexts, the incidence of microabrasion was rare overall at4%. Only tooth and trample marks comprised samples sufficient toexamine their specific co-occurrence with microabrasion. Out of119 specimens with microabrasion, 35 (29%) also had at least oneHC tooth mark, while 44 (37%) also had at least one HC tramplemark (Fisher's p ¼ 0.2708). Thus, at Dikika, microabrasion is rarebut when it does occur it may occur equally in association witheither tooth or trample marks. Analyzed another way, significantlymore HC trample-marked specimens (75%; n ¼ 59) had micro-abrasion than did HC tooth-marked specimens (28%; n ¼ 127)(Fisher's p < 0.0001). This supports Domínguez-Rodrigo et al.’s(2009) observation that trampled bones are more likely to alsoexhibit microabrasion, which has been reported in instances ashigh as 100% in experimental trampling samples. However, it hasbeen reported to occur on 98% of experimental cut-marked bonesthat have been moderately trampled, and at Dikika the incidence ofmicroabrasion is much higher on specimens that have marks (46%of marked specimens) than it is in the overall sample. This suggeststhat if specimens are exposed long enough to acquire any surfacemodifications, then they are also exposed long enough to acquiremoderate abrasion that can occur even after minimal tramplingperiods (Domínguez-Rodrigo et al., 2009). Therefore, the presence/


absence of trampling marks does predict the presence of micro-abrasion, but microabrasion is not a good predictor for what sorts ofother mark morphologies will be found on the same specimen.

5.2. Taphonomic histories at Dikika

Because butchery is a reductive process, and especially becauseactivities such as hammerstone percussion result in fragmentationof bones, the rarity of evidence for butchery damage on assem-blages collected for paleontological purposes may be interpreted inone of several ways: 1) hominin butchery activities were rare acrossthe Pliocene paleolandscape, and the DIK-55 specimens were afortunate discovery; 2) hominin butchery activities were absent,and the marks on the DIK-55 specimens represent a highly unusualcase of equifinality between butcherymarks and another process orprocesses; 3) because samples selected for paleontology typicallydo not include fragmented large-mammal midshafts and ribs e

which a large body of actualistic research has shown are some ofthe most likely specimens to retain butchery damage e there is afalse appearance of rarity of this behavior; 4) the habitats sampledby paleontological studies are not those where hominin butcherytended to occur, or 5) an insufficient number of fossils overall hasbeen examined meaningfully to assess the relative incidence ofbutchery damage or other damage types. The taphonomic datafrom the circle collections provide the first step in evaluating eachof these possibilities, and allowing reconstruction of taphonomicprocesses from surface modification and other lines of evidence atmultiple localities within the DRP area.

Paleoenvironmental and paleoecological interpretations of thehominin-bearing deposits of the Hadar Basin have shown a mosaicof habitats on the landscapes inhabited by australopiths (Bobe et al.,2007; Reed, 2008). Taxonomic abundances of the sieved samplesfrom the DRP area reflect this, but also offer an opportunity toresolve finer details about the spatial distribution of these mosaicenvironments. Although lake and stream deposits preserve fossilswell, australopith behaviormight be expected to be concentrated atlocalities that experienced periods of exposure, rather than placeswhere faunal representation indicates more permanently sub-merged conditions. When all fauna were separated into those thatcould be identified as aquatic or non-aquatic, aquatic specimens byNISP dominate all assemblages (Fig. 10). However, there are sig-nificant differences in the representation of aquatic fauna, with thelocalities of DIK-42 and DIK-43 being particularly rich in taxa suchas fish, aquatic turtles, crocodiles, and hippopotamuses(X2 ¼ 59.916; DF ¼ 6; p < 0.0001). The percentage of aquatic faunaacross the seven localities is negatively correlated with the per-centage of fragments in weathering stage 3 or higher(Rs ¼ �0.8214; p ¼ 0.0356), which supports the inference that lo-calities with high numbers of aquatic fauna were inundated and


Figure 11. Boxplots showing fragment size class distributions at the different localities.Refer to Table 6 for size class categories. Circles and asterisks represent outliers.

Figure 10. Aquatic fauna representation between localities: (a) with fish; and (b)without fish, since fish NISP is likely inflated because of extensive fragmentation.Numbers in bars represent numbers of fragments at each locality.


therefore not exposed to significant episodes of subaerial weath-ering even over the time-averaged scales represented by thecollections.

Bones within sandy sheetwash units may have undergone someweathering before deposition into the lake, but most bones at lo-calities dominated by lacustrine deposits were not exposed tosignificant episodes of subaerial weathering (Table 2). Given thespatial proximity of most localities to one another, each sectionlikely represents a series of depositional environments that wereadjacent to one another over time. The deposition of the fossilswithin them would have also been governed by similar processes(e.g. alternating episodes of lacustrine, sheetwash, mudflat, andchannel deposition), but these episodes are represented in differentproportions by each section. Thus, examining fossils that haderoded from these sections provides a time-averaged sample ofthese different proportions of habitats e a scale that lies betweenthe largest landscape scale and the smallest microhabitat scale thatwould require excavation of individual facies and result in a smalleroverall fossil sample.

Within the aquatic fauna category, fish are a special case. Theyrepresent between 21 and 56% of all specimens by NISP across thedifferent localities, and are differentially distributed between them(X2 ¼ 197.16; DF ¼ 6; p < 0.0001). However, their abundances mayobscure other taxonomic patterning. This is because they can bemore easily identified from small fragments than non-aquatic taxa.


They are also small e no individual fish fragment in any collectionwas larger than 5 cm. Small fragments may travel farther duringpost-depositional fluvial transport (Behrensmeyer, 1988; Pante andBlumenschine, 2010), so assemblages from localities with a lot offish may represent autochthonous accumulations of fish in lacus-trine deposits or allochthonous concentrations of small fragmentsdominated by fish that were transported from elsewhere. Thesedimentological data suggest that the former possibility is morelikely, and the fragment size and edge rounding data providefurther support for this.

The fragment size class data show that the majority of speci-mens from the circle collections are smaller than about 3 cm, andthe skeletal element abundance data show that most are frag-mented and non-diagnostic. This is typical of a sieved assemblagein comparison to non-sieved collections (Shaffer and Sanchez,1994; Bush et al., 2007). Where sieving occurred, the degree ofwinnowing through fluvial transport can be assessed; wherefragment sizes are uniformly distributed, winnowing may be sus-pected (Behrensmeyer, 1988). Pante and Blumenschine (2010)showed that in experimental flume conditions approximately 73%of all fragments smaller than 2 cm are transported, and thus have ahigh probability of being winnowed away from their original lo-cations and redeposited elsewhere. All localities except the BasalMember collection at DIK-58 exhibit a range of fragment sizeclasses (Fig. 11). These size class differences are not the result ofrecent fragmentation, because localities such as DIK-58 and DIK-42have some of the most uniform fragment size classes but some ofthe lowest incidences of fossils with recent breaks. Sedimentolog-ically, DIK-58 is also quite distinct, being dominated by sedimentsindicative of high-energy ephemeral streams.

Determining the degree to which fossils from different localitiesrepresent autochthonous or allochthonous accumulations providesinsight into when and how in their taphonomic histories bonemodifications likely accumulated on their surfaces. Regardless ofthe time-averaging effect of surface collecting, we have found that


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the sum results of the varied depositional environments at eachlocality are different, and they can be categorized along a contin-uum where some experienced a majority of fossil input fromaquatic environments to localities that experienced a majority offossil input from terrestrial environments. An overall assessment ofeach locality is given in Table 12.

After establishing how representative each assemblage is of thedominant depositional and post-depositional processes thatoccurred at that locality, it becomes possible to examine the spatialdistributions of bone-modifying agents that were active ondifferent parts of the paleolandscape, and which left marks on thebone surfaces. Many of the processes associated with these agents(e.g. carnivore gnawing, crocodile modification, microbial bio-erosion, and butchery) typically occur when the bones are in anutritive state, although other processes (e.g. trampling, rootetching, insect invasion, and chemical dissolution) may occur laterin a bone's post-depositional taphonomic history. Characterizationof the main processes that modified bones within the sedimentsrepresented at each locality provides a starting point for futurework, where specific facies of interest can be targeted and tapho-nomic variability might be examined through excavation at themicrohabitat scale.

It is useful to establish where and under what conditions bonesurface modifications are expected to be preserved, as sometaphonomic processes may erase or modify existing bone surfacemarks, such as processes that cause rounding and weathering(Thompson, 2005). Rounding class did not correlate with thenumber of preserved marks (Rs ¼ �0.374; p ¼ 0.5564), which isconsistent with the experimental finding thatmodifications such ascut, percussion, and tooth marks do preserve on bones that havebeen transported within a fluvial system (Pante and Blumenschine,2010). However, on rounded specimens, post-depositional modifi-cations such as marks with trampling morphology do occur morecommonly (9%; n ¼ 8) than do modifications such as tooth marks(3%; n¼ 12). A Fisher's exact test shows these two proportions to besignificantly different (p ¼ 0.0487), which suggests that the timingof interactions between biotic and abiotic processes can beextracted at a finer scale across the landscape.

There is a significant positive correlation between the fragmentsize class of a specimen and the number of marks on its surface(Rs¼ 0.2120; p¼ 0.0007), which has been found to be the casewithboth experimental and archaeological assemblages (Abe et al.,2002; Thompson, 2008). Weathering stage was also significantly,albeit weakly, associated with the number of marks (Rs ¼ 0.1396;p ¼ 0.0272), supporting the inference that longer periods ofexposure open opportunities for modifications to accumulate onbone surfaces. Marks are therefore more likely to occur on largerfragments, and when they do they should represent a palimpsest ofmodifications from a range of agents. Thus, assigning all marks on aspecimen to a single process will overly simplify and ultimatelyconfound our understanding of past taphonomic processes.

With respect to the issue of equifinality, extensive experimen-tation has shown that in any given population of bone surfacemarks there are always some that overlap in morphology withmarks made by other processes. Therefore, large experimental andfossil populations of marked bones are desirable for interpretationand analysis. These are not always available, which is particularlyproblematic for purported butchery marks that pre-date 2.0 Ma.Apart from the two DIK-55 specimens, the overall published sampleof candidate butchered bones prior to ca. 2.0 Ma consists of onlythree specimens from Bouri (de Heinzelin et al., 1999), nine speci-mens (two of which conjoin) from Gona (Domínguez-Rodrigo et al.,2005), a specimen from Hadar (Kimbel et al., 1996), and twospecimens from Lokalalei 1 (Kibunjia, 1994). Of these, only two

Ta Ov

Please cite this article in press as: Thompson, J.C., et al., Taphonomy of fossils from the hominin-bearing deposits at Dikika, Ethiopia, Journal ofHuman Evolution (2015), http://dx.doi.org/10.1016/j.jhevol.2015.06.013


specimens from Bouri, four from Gona (via SEM), and the two fromDikika have been illustrated.

Domínguez-Rodrigo et al. (2005) note that there are a few othersites pre-dating 2.0 Ma that preserve in situ association of stonetools and fossils, but that these sites do not have a demonstratedlink between the two through bone surface modifications. At sitessuch as Excavation 1 at Kanjera South, Kenya, it is noted that bonesurface preservation is good and cut marks may be discerned in thefuture (Plummer et al., 1999), while at Lokalalei 2C (West Turkana,Kenya), bone surfaces are poorly preserved (Roche et al., 1999). Theonly reported hominin modification from this site is brief mentionof one cut mark on a small-medium mammal fragment found onthe surface (Delagnes and Roche, 2005).

This rarity of butchery-marked fossils in itself may be infor-mative about the behavior and ecology of later Australopithecus andearly Homo, but it is impossible to make this evaluation withoutsystematic study of fully-collected fossil assemblages dating to thetime period between ca. 3.5e2.0 Ma. Therefore, we advocate here amulti-pronged approach to interpretation of early homininbehavior that includes systematic taphonomic analysis of fossilsfrom deposits that do not necessarily contain flaked stone tools.This shift in methodology has the potential to address controversialissues, add a new aspect to paleoenvironmental and microhabitatreconstruction, and result in new discoveries on fossils that mayhave been previously overlooked.

6. Conclusions

Combined anatomical, archaeological, ecological and stableisotope data provide the paleobiological, and paleoecologicalcontext of early hominin subsistence between ca. 3.4e2.0 Ma. Noneof these lines of evidence militates against incorporation of largeungulate tissues into the early hominin diet prior to the emergenceof Homo by 2.8 Ma (Villmoare et al., 2015), or in conjunction withthe earliest flaked stone artifacts (Harmand et al., 2015). It is knownthat in the terminal Pliocene, hominins were flaking stone(Harmand et al., 2015). It is not known how or when this behaviororiginated (Panger et al., 2002; Mercader et al., 2007), but it isknown that by 2.6 Ma they had acquired an understanding of rawmaterial selection and fracture mechanics (Stout et al., 2005, 2010)Therefore, to understand the progression of key hominin behaviors,including stone-tool assisted meat-eating, deposits that do notcontain Oldowan tools should be studied with the same care that isgiven to deposits with them.

Descriptions of the abundances, fragmentation patterns, andsurface modifications of different types of fossils and their bonesurface modifications provide detail about the environments andecosystems of which australopiths were a part, and will assist intargeting localities for finer-scale investigation of the microhabitatsthat comprise them. The results of a comprehensive taphonomicstudy of fossils from the DRP are further relevant for interpretationof taphonomic signatures on fossils from nearby fossil-bearingresearch areas such as Hadar, Gona, Woranso-Mille, and Ledi-Geraru.

Our study showed that fossils recovered using protocols 1 and 2from across the DRP area have variably preserved surfaces, withdamage that includes both shallow and deep modifications e thelatter frequently exhibiting characteristics resembling experi-mental crocodile activity. However, no surface modifications exceptthose on the original two DIK-55 specimens occur that would havebeen interpreted as butchery damage using the criteria that wereapplied to initial diagnosis of those marks. Fossils from seven dry-sieved surface collections provide a more systematic assessment ofthe peri-depositional and post-depositional taphonomic processesin operation in the area around DIK-55 and elsewhere in the DRP.


These samples represent fossil input during the sedimentary con-ditions found in the overlying geological sections, and thus can bebroadly characterized in terms of the taphonomic processes thatdominated at each locality. They also allow testing of the hypothesisthat the DIK-55 marks were created through incidental tramplingdamage.

Domínguez-Rodrigo et al. (2010, 2011, 2012) invoked four mainlines of argument to assert that the DIK-55 marks were created bytrampling: 1) parsimony and uniformitarianism associated withtrampling damage, because it is a widespread and naturally-occurring process, whilst butchery damage is rarely documentedprior to 2.0 Ma; 2) the fact that the DIK-55 specimens may havederived from a sandy sediment; 3) the presence of microabrasionon the DIK-55 marks; and 4) the superficial similarity betweenexperimental trample marks and some of the DIK-55 marks. Ourstudy has shown with a large sample of fossils that the DIK-55marks appear both morphologically different, different in theirqualitative variables, and substantially larger than the backgroundpopulation of marks in the DRP area where sedimentary processesand potential conditions for trampling are the same.Moreover, theydiffer in many of these respects from the experimental tramplingdatasets presented by Domínguez-Rodrigo et al. (2009).

Claims of butchery marks on large mammal bones in depositswhere stone tools are rare or absent can be contextualized byanalysis of the surfaces of substantial numbers of other fossilsfound in the same deposits, rather than relying solely on themorphologies of individual marks. This has now been done for theDIK-55 specimens, as part of a larger sample of fossils from Dikika.If the DIK-55 marks were caused by trampling, then we wouldexpect to find other deep, linear marks that resemble cut marks, orat least find that the DIK-55 marks fall within the range of sizes andqualitative characteristics exhibited by linear marks on otherspecimens from the same sedimentary packages e and we do not.Thus, we consider that there is little support for the first argumentby Domínguez-Rodrigo et al. (2010, 2011, 2012) for trampling as thecausal agent behind the DIK-55 marks because it would invoke avery special set of trampling conditions at that locality that have nodirect analog within the current range of experimental tramplingdatasets.

Because the ecological role played by Australopithecus-gradehominins is little known, a major problem of using modern analogsto reconstruct their behavior is predicting and then detecting po-tential signatures of that behavior across the landscape. Themethodology proposed here is one that will enable characteriza-tion of the taphonomic processes in operation across the paleo-landscapes on which australopiths were active, includingstatistically robust assessments of bone surface modifications thathave the potential to provide new information about the paleo-ecology and behavior of Pliocene hominins.

Acknowledgements

We thank the Authority for Research and Conservation of Cul-tural Heritage in Ethiopia for permission to conduct field work andtheir generous access to the fossils curated in their facility, workingspace, and access to a microscope with a camera attachment. Wethank curators Tomas Getachew and Yared Assefa for their help.The Max Planck Institute for Evolutionary Anthropology provided aportable microscope for the study. Moges Mekonnen assisted intransport of fossils between the collections and the workspace. BillKimbel facilitated lodging for JT in Addis Ababa for the duration ofthe study. Funding to conduct field and lab work was provided byMargaret and Will Hearst. We also wish to thank Sarah Elton, J.Tyler Faith, and three anonymous reviewers for their constructivecritique of our original submission.



References

Abe, Y., Marean, C.W., Nilssen, P.J., Assefa, Z., Stone, E.C., 2002. The analysis ofcutmarks on archaeofauna: a review and critique of quantification procedures,and a new image-analysis GIS approach. Amer. Ant. 67, 643e663.

Alemseged, Z., 2003. An integrated approach to taphonomy and faunal change inthe Shungura Formation (Ethiopia) and its implication for hominid evolution.J. Hum. Evol. 44, 451e478.

Alemseged, Z., Wynn, J.G., Kimbel, W.H., Reed, D., Geraads, D., Bobe, R., 2005. A newhominin from the Basal Member of the Hadar Formation, Dikika, Ethiopia, andits geological context. J. Hum. Evol. 49, 499e514.

Alemseged, Z., Spoor, F., Kimbel, W.H., Bobe, R., Geraads, D., Reed, D., Wynn, J.G.,2006. A juvenile early hominin skeleton from Dikika, Ethiopia. Nature 443,296e301.

Archer, W., Braun, D.R., 2013. Investigating the signature of aquatic resource usewithin Pleistocene hominin dietary adaptations. PLoS One 8, e69899.

Aronson, J.L., Taieb, M., 1981. Geology and paleogeography of the Hadar hominidsite, Ethiopia. In: Rapp, G., Vondra, C.F. (Eds.), Hominid Sites: Their GeologicSettings. Westview Press, Boulder, Colorado, pp. 165e195.

Backwell, L.R., Parkinson, A.H., Roberts, E.M., D'Errico, F., Huchet, J.-B., 2012. Criteriafor identifying bone modification by termites in the fossil record. Palaeogeogr.Palaeoclimatol. Palaeoecol. 337e338, 72e87.

Baquedano, E., Domínguez-Rodrigo, M., Musiba, C., 2012. An experimental study oflarge mammal bone modification by crocodiles and its bearing on the inter-pretation of crocodile predation at FLK Zinj and FLK NN3. J. Archaeol. Sci. 39,1728e1737.

Behrensmeyer, A.K., 1978. Taphonomic and ecologic information from boneweathering. Paleobiology 4, 150e162.

Behrensmeyer, A.K., 1988. Vertebrate preservation in fluvial channels. Palaeogeogr.Palaeoclimatol. Palaeoecol. 63, 183e199.

Behrensmeyer, A., Reed, K., 2013. Reconstructing the habitats of Australopithecus:Paleoenvironments, site taphonomy, and faunas. In: Reed, K.E., Fleagle, J.G.,Leakey, R.E. (Eds.), The Paleobiology of Australopithecus. Springer, Netherlands,pp. 41e60.

Behrensmeyer, A.K., Gordon, K.D., Yanagi, G.T., 1986. Trampling as a cause of bonesurface damage and psuedo-cutmarks. Nature 319, 768e771.

Bello, S.M., Soligo, C., 2008. A new method for the quantitative analysis of cutmarkmicromorphology. J. Archaeol. Sci. 35, 1542e1552.

Bello, S.M., Parfitt, S.A., Stringer, C., 2009. Quantitative micromorphological analysesof cut marks produced by ancient and modern handaxes. J. Archaeol. Sci. 36,1869e1880.

Blumenschine, R.J., Marean, C.W., Capaldo, S.D., 1996. Blind tests of inter-analystcorrespondence and accuracy in the identification of cut marks, percussionmarks, and carnivore tooth marks on bone surfaces. J. Archaeol. Sci. 23,493e507.

Blumenschine, R.J., Peters, C.R., 1998. Archaeological predictions for hominid landuse in the Paleo-Olduvai basin, Tanzania, during lowermost Bed II times. J. Hum.Evol. 34, 565e607.

Blumenschine, R.J., Selvaggio, M.M., 1988. Percussion marks on bone surfaces as anew diagnostic of hominid behaviour. Nature 333, 763e765.

Blumenschine, R.J., Stanistreet, I.G., Njau, J.K., Bamford, M.K., Masao, F.T.,Albert, R.M., Stollhofen, H., Andrews, P., Prassack, K.A., McHenry, L.J., Fern�andez-Jalvo, Y., Camilli, E.L., Ebert, J.I., 2012. Environments and hominin activitiesacross the FLK Peninsula during Zinjanthropus times (1.84 Ma), Olduvai Gorge,Tanzania. J. Hum. Evol. 63, 364e383.

Bobe, R., Behrensmeyer, A., Eck, G.G., Harris, J.M., 2007. Patterns of abundance anddiversity in late Cenozoic bovids from the Turkana and Hadar Basins, Kenya andEthiopia. In: Bobe, R., Alemseged, Z., Behrensmeyer, A. (Eds.), Hominin Envi-ronments in the East African Pliocene: An Assessment of the Faunal Evidence.Springer, Netherlands, pp. 129e157.

Brochu, C.A., Njau, J., Blumenschine, R.J., Densmore, L.D., 2010. A new hornedcrocodile from the Plio-Pleistocene hominid sites at Olduvai Gorge, Tanzania.PLoS One 5, e9333.

Bunn, H.T., Stanford, C.B., 2001. Hunting, power scavenging, and butchering by Hadzaforagers and by Plio-Pleistocene Homo. In: Stanford, C., Bunn, H.T. (Eds.), MeatEating and Human Evolution. Oxford University Press, Oxford, pp. 199e218.

Bush, A.M., Kowalewski, M., Hoffmeister, A.P., Bambach, R.K., Daley, G.M., 2007.Potential paleoecologic biases from size-filtering of fossils: strategies forsieving. Palaios 22, 612e622.

Campisano, C.J., Feibel, C.S., 2008. Depositional environments and stratigraphicsummary of the Pliocene Hadar formation at Hadar, Afar depression, Ethiopia.Geol. S. Am. S 446, 179e201.

Cerling, T.E., Wang, Y., Quade, J., 1993. Expansion of C4 ecosystems as an indicator ofglobal ecological change in the late Miocene. Nature 361, 344e345.

Cerling, T.E., Manthi, F.K., Mbua, E.N., Leakey, L.N., Leakey, M.G., Leakey, R.E.,Brown, F.H., Grine, F.E., Hart, J.A., Kaleme, P., 2013. Stable isotope-based dietreconstructions of Turkana Basin hominins. Proc. Natl. Acad. Sci. 110,10501e10506.

Cleghorn, N.E., 2006. A zooarchaeological perspective on the middle to upperpaleolithic transition at Mezmaiskaya Cave, the northwestern Caucasus, Russia.Ph.D. Dissertation, State University of New York at Stony Brook.

de Heinzelin, J., Clark, J.D., White, T.D., Hart, W.K., Reene, P., WoldeGabriel, G.,Beyene, Y., Vrba, E., 1999. Environment and behavior of 2.5-million-year-oldBouri hominids. Science 284, 625e635.


Delagnes, A., Roche, H.l.N., 2005. Late Pliocene hominid knapping skills: the case ofLokalalei 2C, West Turkana, Kenya. J. Hum. Evol. 48, 435e472.

Domínguez-Rodrigo, M., 2008. Conceptual premises in experimental design andtheir bearing on the use of analogy: an example from experiments on cutmarks. World Archaeol. 40, 67e82.

Domínguez-Rodrigo, M., Barba, R., 2006. New estimates of tooth mark and per-cussion mark frequencies at the FLK Zinj site: the carnivore-hominid-carnivorehypothesis falsified. J. Hum. Evol. 50, 170e194.

Domínguez-Rodrigo, M., Barba, R., 2007. Five more arguments to invalidate thepassive scavenging version of the carnivore-hominid-carnivore model: a replyto Blumenschine et al. (2007a). J. Hum. Evol. 53, 427e433.

Domínguez-Rodrigo, M., Yravedra, J., 2009. Why are cut mark frequencies inarchaeofaunal assemblages so variable? A multivariate analysis. J. Archaeol. Sci.36, 884e894.

Domínguez-Rodrigo, M., de la Torre, I., de Luque, L., Alcal, L., Mora, R., Serrallonga, J.,Medina, V., 2002. The ST site complex at Peninj, West Lake Natron, Tanzania:implications for early hominid behavioural models. J. Archaeol. Sci. 29,639e666.

Domínguez-Rodrigo, M., Pickering, T.R., Semaw, S., Rogers, M.J., 2005. Cutmarkedbones from Pliocene archaeological sites at Gona, Afar, Ethiopia: Implicationsfor the function of the world's oldest stone tools. J. Hum. Evol. 48, 109e121.

Domínguez-Rodrigo, M., de Juana, S., Gal�an, A.B., Rodríguez, M., 2009. A new pro-tocol to differentiate trampling marks from butchery cut marks. J. Archaeol. Sci.36, 2643e2654.

Domínguez-Rodrigo, M., Pickering, T.R., Bunn, H.T., 2010. Configurational approachto identifying the earliest hominin butchers. Proc. Natl. Acad. Sci. 107,20929e20934.

Domínguez-Rodrigo, M., Pickering, T.R., Bunn, H.T., 2011. Reply to McPherron et al.:Doubting Dikika is about data, not paradigms. Proc. Natl. Acad. Sci. 108.E117eE117.

Domínguez-Rodrigo, M., Pickering, T., Bunn, H.T., 2012. Experimental study of cutmarks made with rocks unmodified by human flaking and its bearing on claimsof ~3.4-million-year-old butchery evidence from Dikika, Ethiopia. J. Archaeol.Sci. 39, 205e214.

Feakins, S.J., Levin, N.E., Liddy, H.M., Sieracki, A., Eglinton, T.I., Bonnefille, R., 2013.Northeast African vegetation change over 12 my. Geology 41, 295e298.

Fernandez-Jalvo, Y., 2012. A rare case of human activity mimicking carnivoredamage (Tianyuandong, China). Quatern. Int. 141, 279e280.

Fisher Jr., J.W., 1995. Bone surface modifications in zooarchaeology. J. Arch. Meth.Theor. 2, 7e68.

Gifford, D.P., 1981. Taphonomy and paleoecology: a critical review of archaeology'ssister disciplines. Adv. Archaeol. Meth. Theor 4, 365e439.

Gifford-Gonzales, D., 1991. Bones are not enough: Analogues, knowledge, andinterpretive strategies in zooarchaeology. J. Anthrop. Archaeol. 10, 215e254.

Hammer, Ø., Harper, D.A.T., Ryan, P.D., 2001. PAST: Paleontological statistics soft-ware package for education and data analysis. Palaeontol. Electron. 4, 1e9.

Hardus, M., Lameira, A., Zulfa, A., Atmoko, S.S., Vries, H., Wich, S., 2012. Behavioral,ecological, and evolutionary aspects of meat-eating by Sumatran orangutans(Pongo abelii). Int. J. Primatol. 33, 287e304.

Harmand, S., Lewis, J., Feibel, C.S., Lepre, C.J., Sandrine, P., Lenoble, A., Bo€es, X.,Quinn, R., Brenet, M., Arroyo, A., Taylor, N., Cl�ement, S., Daver, G., Brugal, J.-P.,Leakey, L., Mortlock, R.A., Wright, J.D., Lokorodi, S., Kirwa, C., Kent, D.V.,Roche, H., 2015. 3.3-million-year-old stone tools from Lomekwi 3, West Tur-kana, Kenya. Nature 521, 310e315.

James, E.C., Thompson, J.C., 2015. On bad terms: Problems and solutions withinzooarchaeological bone surface modification studies. Environ. Archaeol. 20,89e103.

Karr, L.P., Outram, A.K., 2012. Actualistic research into dynamic impact and its im-plications for understanding differential bone fragmentation and survivorship.J. Archaeol. Sci. 39, 3443e3449.

Kibunjia, M., 1994. Pliocene archaeological occurrences in the Lake Turkana basin.J. Hum. Evol. 27, 159e171.

Kimbel, W.H., Walter, R.C., Johanson, D.C., Reed, K.E., Aronson, J.L., Assefa, Z.,Marean, C.W., Eck, G.G., Bobe, R., Hovers, E., Rak, Y., Vondra, C., Yemane, T.,York, D., Chen, Y., Evensen, N.M., Smith, P.E., 1996. Late Pliocene Homo andOldowan tools from the Hadar Fromation (Kada Hadar Member), Ethiopia.J. Hum. Evol. 31, 549e561.

Lee-Thorp, J.A., Sponheimer, M., Passey, B.H., de Ruiter, D.J., Cerling, T.E., 2010. Stableisotopes in fossil hominin tooth enamel suggest a fundamental dietary shift inthe Pliocene. Phil. Trans. R. Soc. B 365, 3389e3396.

Marean, C.W., 1995. Of taphonomy and zooarcheology: review of VertebrateTaphonomy by R. Lee Lyman (1994). Evol. Anthrop. 4, 64e72.

Marean, C.W., Ehrhardt, C.E., 1995. Paleoanthropological and paleoecological im-plications of the taphonomy of a sabertooth's lair. J. Hum. Evol. 28, 515e547.

Marean, C.W., Abe, Y., Frey, C.J., Randall, R.C., 2000. Zooarchaeological and tapho-nomic analysis of the Die Kelders Cave 1 Layers 10 and 11 Middle Stone Agelarger mammal fauna. J. Hum. Evol. 38, 197e233.

Marshall, A., Wrangham, R., 2007. Evolutionary consequences of fallback foods. Int.J. Primatol 28, 1219e1235.

McCoy, J., 2009. Ecological and behavioral implications of new archaeological oc-currences from upper burgi exposures at Koobi Fora, Kenya. PhD Dissertation,Rutgers State University of New Jersey.

McPherron, S.P., Alemseged, Z., Marean, C.W., Wynn, J.G., Reed, D., Geraads, D.,Bobe, R., Bearat, H.A., 2010. Evidence for stone-tool-assisted consumption of


http://refhub.elsevier.com/S0047-2484(15)00165-7/sref1

































































































































































































































animal tissues before 3.39 million years ago at Dikika, Ethiopia. Nature 466,857e860.

McPherron, S.P., Alemseged, Z., Marean, C., Wynn, J.G., Reed, D., Geraads, D.,Bobe, R., B�earat, H., 2011. Tool-marked bones from before the Oldowan changethe paradigm. Proc. Natl. Acad. Sci. 108. E116eE116.

Mercader, J., Barton, H., Gillespie, J., Harris, J., Kuhn, S., Tyler, R., Boesch, C., 2007.4,300-year-old chimpanzee sites and the origins of percussive stone technol-ogy. Proc. Natl. Acad. Sci. 104, 3043e3048.

Newman, S.E., 2015. Applications of Reflectance Transformation Imaging (RTI) tothe study of bone surface modifications. J. Archaeol. Sci. 53, 536e549.

Njau, J., 2012. Reading Pliocene bones. Science 336, 46e47.Njau, J.K., Blumenschine, R.J., 2006. A diagnosis of crocodile feeding traces on larger

mammal bone, with fossil examples from the Plio-Pleistocene Olduvai Basin,Tanzania. J. Hum. Evol. 50, 142e162.

Oliver, J.S., 1989. Analogues and site context: bone damage from Shield Trap Cave(24CB91), Carbon County, Montana, USA. In: Bonnichsen, R., Sorg, M.H. (Eds.),Bone Modification. Center for the Study of the First Americans, Orono, Maine,pp. 73e98.

Olsen, S.L., Shipman, P., 1988. Surface modification on bone: trampling versusbutchery. J. Archaeol. Sci. 535e553.

Panger, M.A., Brooks, A.S., Richmond, B.G., Wood, B., 2002. Older than the Old-owan? Rethinking the emergence of hominin tool use. Evol. Anthrop. 11,235e245.

Pante, M.C., Blumenschine, R.J., 2010. Fluvial transport of bovid long bones frag-mented by the feeding activities of hominins and carnivores. J. Archaeol. Sci. 37,846e854.

Pante, M.C., Blumenschine, R.J., Capaldo, S.D., Scott, R.S., 2012. Validation of bonesurface modification models for inferring fossil hominin and carnivore feedinginteractions, with reapplication to FLK 22, Olduvai Gorge, Tanzania. J. Hum.Evol. 63, 395e407.

Pickering, T.R., Egeland, C.P., 2006. Experimental patterns of hammerstone per-cussion damage on bones: implications for inferences of carcass processing byhumans. J. Archaeol. Sci. 33, 459e469.

Pickering, T.R., Clarke, R.J., Heaton, J.L., 2004a. The context of Stw 573, an earlyhominid skull and skeleton from Sterkfontein Member 2: taphonomy andpaleoenvironment. J. Hum. Evol. 46, 277e295.

Pickering, T.R., Clarke, R.J., Moggi-Cecchi, J., 2004b. Role of carnivores in the accu-mulation of the Sterkfontein Member 4 hominid assemblage: A taphonomicreassessment of the complete hominid fossil sample (1936e1999). Am. J. Phys.Anthropol. 125, 1e15.

Plummer, T., Bishop, L., 1994. Hominid paleoecology at Olduvai Gorge, Tanzania asindicated by antelope remains. J. Hum. Evol. 27, 47e75.

Plummer, T., Bishop, L.C., Ditchfield, P., Hicks, J., 1999. Research on Late PlioceneOldowan Sites at Kanjera South, Kenya. J. Hum. Evol. 36, 151e170.

Pobiner, B.L., 2008. Apples and oranges again: comment on ‘Conceptual premises inexperimental design and their bearing on the use of analogy: an example fromexperiments on cut marks’. World Archaeol. 40, 466e479.

Potts, R., Behrensmeyer, A.K., Ditchfield, P., 1999. Paleolandscape variation and EarlyPleistocene hominid activities: members 1 and 7, Olorgesailie Formation,Kenya. J. Hum. Evol. 37, 747e788.

Reed, K.E., 2008. Paleoecological patterns at the Hadar hominin site, Afar RegionalState, Ethiopia. J. Hum. Evol. 54, 743e768.

Roche, H., Delagne, A., Brugal, J.P., Feibel, C., Kibunjia, M., Mourre, Texier, P.J., 1999.Early homind stone tool production and technical skill 2.34 myr ago in WestTurkana, Kenya. Nature 399, 57e59.

Scott, R.S., Ungar, P.S., Bergstrom, T.S., Brown, C.A., Grine, F.E., Teaford, M.F.,Walker, A., 2005. Dental microwear texture analysis shows within-species dietvariability in fossil hominins. Nature 436, 693e695.

Shaffer, B.S., Sanchez, J.L., 1994. Comparison of 1/80 0-and 1/40 0-mesh recovery ofcontrolled samples of small-to-medium-szed mammals. Amer. Ant. 525e530.

Sponheimer, M., Alemseged, Z., Cerling, T.E., Grine, F.E., Kimbel, W.H., Leakey, M.G.,Lee-Thorp, J.A., Manthi, F.K., Reed, K.E., Wood, B.A., 2013. Isotopic evidence ofearly hominin diets. Proc. Natl. Acad. Sci. 110, 10513e10518.


Stewart, K.M., 2014. Environmental change and hominin exploitation of C4-basedresources in wetland/savanna mosaics. J. Hum. Evol. 77, 1e16.

Stout, D., Quade, J., Semaw, S., Rogers, M.J., Levin, N.E., 2005. Raw material selec-tivity of the earliest stone toolmakers at Gona, Afar, Ethiopia. J. Hum. Evol. 48,365e380.

Stout, D., Semaw, S., Rogers, M.J., Cauche, D., 2010. Technological variation in theearliest Oldowan from Gona, Afar, Ethiopia. J. Hum. Evol. 58, 474e491.

Strait, D.S., Weber, G.W., Neubauer, S., Chalk, J., Richmond, B.G., Lucas, P.W.,Spencer, M.A., Schrein, C., Dechow, P.C., Ross, C.F., Grosse, I.R., Wright, B.W.,Constantino, P., Wood, B.A., Lawn, B., Hylander, W.L., Wang, Q., Byron, C.,Slice, D.E., Smith, A.L., 2009. The feeding biomechanics and dietary ecology ofAustralopithecus africanus. Proc. Natl. Acad. Sci. 106, 2124e2129.

Su, D.F., Harrison, T., 2008. Ecological implications of the relative rarity of fossilhominins at Laetoli. J. Hum. Evol. 55, 672e681.

Surovell, T., Grund, B., 2012. The associational critique of Quaternary overkill andwhy it is largely irrelevant to the extinction debate. Amer. Ant. 77, 672e687.

Tappen, M., Adler, D.S., Ferring, C.R., Gabunia, M., Vekua, A., Swisher III, C.C., 2002.Akhalkalaki: the taphonomy of an Early Pleistocene locality in the Republic ofGeorgia. J. Archaeol. Sci. 29, 1367e1391.

Thompson, J.C., 2005. The impact of post-depositional processes on bone surfacemodification frequencies: a corrective strategy and its application to theLoiyangalani site, Serengeti Plain, Tanzania. J. Taphonomy 3, 57e80.

Thompson, J.C., 2008. Zooarchaeological tests for modern human behavior atBlombos Cave and Pinnacle Point Cave 13B, southwestern Cape, South Africa.Ph.D. Dissertation, Arizona State University.

Thompson, J.C., 2010. Taphonomic analysis of the faunal assemblage from PinnaclePoint Cave 13B, Western Cape, South Africa. J. Hum. Evol. 59, 321e339.

Thompson, J.C., Henshilwood, C.S., 2011. Taphonomic analysis of the Middle StoneAge larger mammal faunal assemblage from Blombos Cave, southern Cape,South Africa. J. Hum. Evol. 60, 746e767.

Thompson, J.C., Lansing, S., Marean, C.W., McPherron, S.P., Alemseged, Z., 2011.Experimental definition of bone surface signatures from natural unmodifiedstones and implications for early hominin subsistence. PaleoAnthropology 2011,A35.

Ungar, P., 2004. Dental topography and diets of Australopithecus afarensis and earlyHomo. J. Hum. Evol. 46, 605e622.

Ungar, P.S., Scott, R.S., Grine, F.E., Teaford, M.F., 2010. Molar microwear textures andthe diets of Australopithecus anamensis and Australopithecus afarensis. Phil.Trans. R. Soc. B 365, 3345e3354.

Villa, P., Mahieu, E., 1991. Breakage patterns of human long bones. J. Hum. Evol. 21,27e48.

Villmoare, B., Kimbel, W.H., Seyoum, C., Campisano, C.J., DiMaggio, E.N., Rowan, J.,Braun, D.R., Arrowsmith, J.R., Reed, K.E., 2015. Early Homo at 2.8 Ma from Ledi-Geraru, Afar, Ethiopia. Science 347, 1352e1355.

Walter, R.C., 1981. The volcanic history of the Hadar early-man site and the sur-rounding Afar region of Ethiopia, Department of Geological Sciences. PhDDissertation, Case Western Reserve University.

White, T.D., Ambrose, S.H., Suwa, G., Su, D.F., DeGusta, D., Bernor, R.L., Boisserie, J.-R.,Brunet, M., Delson, E., Frost, S., 2009. Macrovertebrate paleontology and thePliocene habitat of Ardipithecus ramidus. Science 326, 67e93.

Wrangham, R., Conklin-Brittain, N., 2003. Cooking as a biological trait. Comp. Bio-chem. Phys. A 136, 35e46.

Wynn, J.G., Alemseged, Z., Bobe, R., Geraads, D., Reed, D., Roman, D.C., 2006.Geological and palaeontological context of a Pliocene juvenile hominin atDikika, Ethiopia. Nature 443, 332e336.

Wynn, J.G., Roman, D.C., Alemseged, Z., Reed, D., Geraads, D., Munro, S., 2008.Stratigraphy, depositional environments, and basin structure of the Hadar andBusidima Formations at Dikika, Ethiopia. Geol. S. Am. S. 446, 87e118.

Wynn, J.G., Sponheimer, M., Kimbel, W.H., Alemseged, Z., Reed, K., Bedaso, Z.K.,Wilson, J.N., 2013. Diet of Australopithecus afarensis from the Pliocene HadarFormation, Ethiopia. Proc. Natl. Acad. Sci. 110, 10495e10500.












































































































































































Taphonomy of fossils from the hominin-bearing deposits at Dikika, Ethiopia

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