Palaeogeography, Palaeoclimatology, Palaeoecology 423 (2015) 44–52

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Palaeogeography, Palaeoclimatology, Palaeoecology

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Rocky shore taphonomy—A comparative study of modern and LateCretaceous analogues

Anne Mehlin Sørensen ⁎, Finn SurlykDepartment of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, Dk-1350 Copenhagen K, Denmark

⁎ Corresponding author. Tel.: +45 35325743.E-mail addresses: anne@ign.ku.dk (A.M. Sørensen), fin

http://dx.doi.org/10.1016/j.palaeo.2015.01.0260031-0182/© 2015 Elsevier B.V. All rights reserved.

a b s t r a c t

a r t i c l e i n f o

Article history:Received 24 June 2014Received in revised form 19 January 2015Accepted 24 January 2015Available online 4 February 2015

Keywords:TaphonomyRocky shoreMolluscsLate CretaceousTime averagingSweden

Rocky shores are rare in the fossil record due to erosion under both sea-level rise and fall. In contrast, modernrocky shores are well-studied, but little is known about the evolution of their ecosystems due to the rarity of an-cient counterparts. Reconstruction of these ancient ecosystems is thus essential to get an insight into their evo-lution. A high-diversity Late Cretaceous (Campanian) rocky shore fauna is found in southern Sweden. Theoriginal composition of the shelly fauna cannot be interpreted by direct examination of the preserved faunadue to the effects of taphonomic processes. Life and death assemblages from a modern rocky shore fauna fromThailand have previously been analysed and a hypothetical fossil assemblage was reconstructed in order to at-tempt an interpretation of the Campanian life assemblage. This study shows a low taxonomic agreement be-tween the original Campanian life assemblage and the fossil assemblage, due to taphonomic processes, andhigh environmental fidelity with only a few out-of-habitat species represented. The modern life assemblageshowed in an earlier study, a high loss of species before onset of fossilisation. This suggests that the faunal com-position of the Campanian life assemblage cannot be easily reconstructed, and time averaging by generations ofdeath assemblagesmakes this evenmore difficult. The Campanian aragonitic fauna is poorly represented and therarity of moulds after aragonitic species is interpreted as due to taphonomic processes and not to lower richnessof aragonitic species in the Cretaceous. This is supported by comparison with the high richness of aragonitic spe-cies found on a Late Cretaceous rocky shore in Germany. An originally high-diversity gastropod fauna is thusinterpreted to have dominated the intertidal zone in the Campanian example, and the rare moulds of each ofthe aragonitic species indicate a high taphonomic loss in spite of rapid burial. Calcitic species-richness is higherin the Campanian fauna than in the modern life, death, and constructed hypothetical fossil assemblages. This isinterpreted as reflecting time averaging of generations of calcitic species and low loss of calcitic species by taph-onomic processes in the Campanian fauna. It is thus assumed that the original Campanian fauna experienced achange in faunal composition from a gastropod-dominated life assemblage to a bivalve-dominated fossil assem-blage due to dissolution of aragonite and excellent preservation of calcite. Reconstruction of ancient rocky shoreshelly faunas can thus be considerably improved by comparison with analogous modern rocky shore faunas.

© 2015 Elsevier B.V. All rights reserved.

1. Introduction

Rocky shores and their associated biotas are rare in the fossil recordeven though their modern counterparts cover approximately 33% ofpresent day coastlines (Johnson and Baarli, 2012). The fossil faunasare mainly poorly preserved due to high-energy conditions underboth transgressive and regressive erosion. Reconstruction of these an-cient marine ecosystems thus requires fundamental insight into tapho-nomic processes working on the skeletal remains in order to correctlyevaluate, interpret, and apply the fossil data. Comparative studies ofmodern life and associated death assemblages are, however, useful inthe interpretation of the composition of fossil assemblages becausedeath assemblages form the basis for the resulting fossil assemblages.

ns@ign.ku.dk (F. Surlyk).

Many factors change the faunal composition of a life assemblage on itsway to the resulting death assemblage. They include different preserva-tion potential of species, out-of-habitat transportation, and time averag-ing of remains frommany successive generations of specieswhichwerenot actually alive at the same time. This means that the composition ofthe life assemblage has changed even before onset of burial andfossilization.

Taphonomic processes act on death assemblages on their way to be-coming a fossil assemblage. These processes include mechanical andbiogenic destruction and carbonate dissolution of shells during burial.Under normal taphonomic burial conditions aragonitic shells are gener-ally dissolved especially in coarse-grained deposits, but if cementation issufficiently early, aragonitic shells can be preserved as moulds (Chernsand Wright, 2000, 2009; Wright et al., 2003; Cherns et al., 2011). Themould preservation potential of aragonite-shelled species is higher forinfaunal than for epifaunal organisms since they are commonly already

45A.M. Sørensen, F. Surlyk / Palaeogeography, Palaeoclimatology, Palaeoecology 423 (2015) 44–52

Fig. 2.Map showing Phuket Island, Thailand. The locations for collecting life and death assemblages are indicated by asterisks (from Sørensen and Surlyk, 2013).

46 A.M. Sørensen, F. Surlyk / Palaeogeography, Palaeoclimatology, Palaeoecology 423 (2015) 44–52

buried before their death and better in shallow water high energy set-tings, where microbial dissolution is reduced (Best and Kidwell, 2000;Lazo, 2004; Cherns et al., 2011). In many ancient limestones mouldsare the only evidence of the former presence of aragonitic shells.

A comparative study of a modern rocky shore mollusc fauna fromThailand showed that only 61% of the species from the life assemblagewere represented in the death assemblage, indicating a high loss of spe-cies from the life assemblage before thebeginning of burial and fossiliza-tion (Sørensen and Surlyk, 2013). The loss was interpreted as resultingfrom mechanical post-mortem destruction and by bioerosion. Shellstructure, shell mineralogy, and size of species had little or no influenceon the loss (Sørensen and Surlyk, 2013). The taxonomic agreement

Fig. 1. A–N Representatives of different fossils found at Ivö Klack, 1–3 specimens from the lifequinquecostata (Sowerby, 1814), bivalve; C. Spondylus labiatus (Wahlenberg, 1821), bivalve; D.guascoi (Bosquet, 1857), cirriped; G1–2.Neomesogastropoda aff. Naticidae sp., gastropod. 1) apigastropod borehole of the ichnospecies Oichnus simplex probably produced by a muricid gastr1819), brachiopod; L. Ancistrocrania stobaei (Lundgren, 1885), brachiopod; M. Biradiolites suecicucullata (Born, 1778), bivalve; 2.Nerita costata Gmelin, 1791, bivalve; 3. Cellana radiata (Born,their morphological similarities and thus inferred similarities in modes of lives.

between the life and death assemblages from Thailand is lower com-pared to earlier studies. In studies from temperate and tropical latitudes90% of the intertidal species were also found in the associated death as-semblages and an average of 98% of the coastal subtidal species and 75%of the species on continental shelves are also found in associated deathassemblages (Kidwell and Flessa, 1996; Behrensmeyer et al., 2000).The environmental fidelity (the similarity between two assemblageswith respect to the preferred habitats of the species without respect totaxonomy) between the modern life and death assemblages was highand only few exotic species were transported into the death assemblagefrom adjacent habitats. A hypothetical fossil assemblage was construct-ed based on the death assemblage by inferring the taphonomic features

assemblage from Thailand; all specimens natural size. A. Clausastrea sp., coral; B. NeitheaRastellum diluvianum (Linnaeus, 1767), bivalve; E. Campanile sp., gastropod; F. Brachylepascal view, 2) side view;H. ‘Rhynchonella’ triangularis (Wahlenberg, 1821), brachiopodwith aopod; I. Otostoma sp. gastropod; J. Patella sp., gastropod; K. Rectithyris depressa (Lamarck,cus (Lundgren, 1870), bivalve; N. Trisalenia loveni (Cotteau, 1859), echinoid; 1. Saccostrea1778), bivalve. D and 1, I and 2, and J and 3 are ancient and modern counterparts showing

47A.M. Sørensen, F. Surlyk / Palaeogeography, Palaeoclimatology, Palaeoecology 423 (2015) 44–52

which acted on the shells. Itwas assumed that all calcitic and all infaunalaragonitic species would be preserved, whereas epifaunal aragoniticspecies were lost (Sørensen and Surlyk, 2013). With a loss of all epifau-nal aragonitic species only 30% of the species from the death assemblageand a 6% of the species from the life assemblage would be preserved onthe way to the constructed hypothetical fossil assemblage. The taxo-nomic agreement between the original life and the constructed hypo-thetical fossil assemblages was thus low, whereas the environmentalfidelity was high (Sørensen and Surlyk, 2013). The study showed thatan ancient rocky shore fossil assemblage will be overrepresented in in-faunal aragonitic bivalves compared to the original life assemblage andthere will be a change in the faunal composition from a gastropod-dominated life assemblage to a bivalve-dominated fossil assemblagedue to preservation potential. A rocky shore environment can thus beinterpreted from an actual fossil assemblage but the faunal composition,trophic structure, diversity and density patterns of themollusc commu-nity have changed dramatically from the original census life assemblage(Sørensen and Surlyk, 2013).

A Late Cretaceous, Campanian rocky shore with a rich shallow ma-rine fauna is found at Ivö in southern Sweden (Surlyk and Sørensen,2010). The shelly fauna comprises 242 benthic invertebrate species, in-cluding bivalves, gastropods, echinoderms, corals, polychaetes, brachio-pods, bryozoans, and cirripeds (Fig. 1). The fauna is the richest and bestpreserved fossil rocky shore fauna known, and is thus excellent to usefor comparison with modern analogues and to form the basis for a re-construction of the ancient life assemblage (cf. Johnson and Baarli,1999, 2012). Modern rocky shore faunas have high species richnessesdue to the many different life forms which have appeared throughtime such as clinging but mobile gastropods, fixed bivalves adapted tobyssate and wedging habits, and the many balanomorph barnacles(Johnson and Baarli, 1999, 2012). These faunal groups and life forms

500 km

Late Cretaceous landmasses

Greenland

Fig. 3. Palaeogeography of NW Europe during the Late Cretaceous. The rocky shore locality at Iv(1990) and Surlyk et al. (2003).

are all present at Ivö, showing that relatively high rocky shore rich-nesses were established during the Campanian. Comparison betweenthe shelly invertebrate fauna of the Campanian and those of similarmodern rocky shores thus offers an outstanding possibility for interpre-tation of the amount and nature of the taphonomic loss of the fossilfauna from death through burial to emergence and succeedingpalaeoecological study.

The aim of the present study is to evaluate the nature and degree oftaphonomic loss in the shelly fauna of the Campanian rocky shore byapplying the results from the study of a modern rocky shore faunain Thailand, forming the basis for reconstruction of a high-fidelityversion of the Campanian and other similar ancient rocky shore lifeassemblages.

2. Setting of the rocky shores

2.1. The modern rocky shore

The modern example is situated on the SW coast of Phuket Islandadjacent to the western coast of the Thai Peninsula in southernThailand (Fig. 2). The island has a monsoonal climate with a dry seasondominated by a NE-monsoon from November to April and a rainy sea-son dominated by a SW-monsoon from May to October. The diurnaltidal range varies about 3.5m from the lowest lowwater level recordedat Phuket and the coastal mean water temperature ranges between26 and 31 °C with a relatively constant salinity of 32 to 33‰(Limpsaichol, 1981; Scoffin et al., 1992). The SW coast of the island iscomposed of granitic rocky shores with sandy pocket beaches in be-tween. Rocky reefs with a high density of corals occur seaward of theshores (Sørensen and Surlyk, 2013).

Sweden

Denmark

Norway

Baltic Shield

Ivö Klack*

ö is indicated by an asterisk. Based on Hancock (1976), Tyson and Funnell (1987), Ziegler

48 A.M. Sørensen, F. Surlyk / Palaeogeography, Palaeoclimatology, Palaeoecology 423 (2015) 44–52

2.2. The Campanian rocky shore

The ancient rocky shore was steep and hilly and was composed ofPrecambrian gneiss. During the Late Cretaceous transgression theweathered gneiss slope was drowned and cleaned by waves, leaving ahigh, steep and irregular hummocky and boulder-strewn rocky shore.The gneissic rocky shore was continuously overlain by carbonates. TheLate Cretaceous the rocky shore locality is located in the KristianstadBasin situated at the north-eastern margin of the extensive epeiricChalk Sea, which covered most of NW Europe during this time interval(Fig. 3). The sea level was about 100 m higher than today (Kominzet al., 2008) and the palaeolatitude was approximately 50°N with awarm temperate to subtropical climate (Smith et al., 1994). The ancientrocky shore is exposed in an abandoned kaolin and limestone quarry onthe island of Ivö in NE Skåne, southern Sweden (Fig. 4). The carbonatesuccession at the rocky shore is at least 25 m thick and consists of ma-rine coarse-grained skeletal sand, gravel and whole fossils composedprimarily of bivalves, bryozoans, brachiopods and echinoids with adominance of oysters (Surlyk and Sørensen, 2010). The successionwas deposited during the late early Campanian (Belemnellocamaxmammilatus belemnite biozone, c. 81–80 Ma; Christensen, 1975).

Fig. 5.Number of gastropod and bivalve species in themodern life, death, and constructedhypothetical fossil assemblages from Thailand, and in the Campanian fossil assemblagefrom Sweden.

3. The Campanian rocky shore fauna

The preserved Campanian rocky shore fauna comprises 242 benthicinvertebrate species, including 61 bivalve, 44 cyclostome bryozoan, 27brachiopod, 25 polychaete, 22 cirriped, 17 gastropod, 16 asteroid, 18echinoid, and 12 coral species. In addition a rich vertebrate fauna com-prising more than 60 species of sharks, mosasaurs, plesiosaurs, croco-diles and aquatic birds has been found in the basin (Sørensen et al.,2013). The fauna has been collected since quarrying started in 1888and many of the rarer species were found during quarrying activitiesin 1915–1925. The fauna has been studied with respect to taxonomyand mode of life primarily based on functional shell morphology and

Fig. 4. Simplified geological map of north-eastern Skåne, southern Sweden, showing the Kristlocated.

comparison with living relatives (Sørensen, 2008; Sørensen andSurlyk, 2010, 2011; Sørensen et al., 2011, 2012; Gale and Sørensen,2014, in press).

The molluscan part of the fauna includes 61 bivalve and 17 gastro-pod species (Fig. 5). A total of 42 species had a calcitic shell, 29 had anaragonitic shell and are preserved asmoulds, and seven species had un-known shell mineralogy (Fig. 6). The fauna comprises 51 epifaunal spe-cies, 23 infaunal species, and four species with an uncertain life position(Fig. 7; Table 1).

ianstad Basin, the location of the island Ivö and the quarry where the fossil rocky shore is

Fig. 6.Number of aragonitic and calcitic species in themodern life, death, and hypotheticalfossil assemblages from Thailand, and the Campanian fossil assemblage from Sweden.

49A.M. Sørensen, F. Surlyk / Palaeogeography, Palaeoclimatology, Palaeoecology 423 (2015) 44–52

4. Discussion

4.1. Preservation of the Campanian rocky shore fauna

Of the 242 benthic invertebrate species found at the Campanianrocky shore 199 are calcitic and 39 are moulds after aragonitic species.The high amount of calcitic compared to aragonitic species is due tothe better preservation potential for calcite together with the abun-dance of calcite-shelled faunal groups, such as bryozoans, polychaetes,cirripedes, echinoderms, and brachiopods. Gastropods, corals, andburrowing bivalves are rare to almost absent, undoubtedly reflectingtheir aragonitic skeletal mineralogy. Numerous drill holes referred tothe ichnospeciesOichnus simplexweremade by carnivorous gastropods,indicating the former presence of muricid gastropods (cf. Bromley,1981) even though body fossils representing this group have notbeen found (Sørensen and Surlyk, 2011, Fig. 1 H). Large-sized, well-preserved calcitic brachiopods and bivalves are abundant (Fig. 1D, K).There is a lack of especially juvenile brachiopods, probably due to shellbreakage and fragmentation in the turbulent environment. However,many small-sized, thin-shelled brachiopods are preserved underneathboulders. Their high abundance and good preservation state areinterpreted as due to a life position in protected habitats where their

Fig. 7. Number of epifaunal and infaunal species in the modern life, death, and hypothet-ical fossil assemblages from Thailand, and in the Campanian fossil assemblage fromSweden.

shells could lie protected from waves and currents after death. Smalldelicate or juvenile calcitic species were thus able to be preserved inprotected areas, whereas only large-sized, thick-shelled calcitic speciesare preserved in the high-energy areas along the shore.

4.2. The preferred habitats of the Campanian rocky shore mollusc fauna

The 14 identified Campanian gastropod species were all rocky shoreinhabitants based on comparison with modern relatives (Sørensen andSurlyk, 2011). A total of 40 of the 61 Campanian bivalve species wererocky shore inhabitants and 16 species lived in the adjacent shallowsubtidal environment. The preferred habitat of 56 bivalve species conse-quently all fits well with the rocky shore environment. Four specieshave an unknown preferred habitat and one species probably preferredthe deep subtidal environment and is thus out-of-habitat (Sørensenet al., 2012). The preferred habitats of the fossil rocky shore mollusc as-semblage show that the fauna had a high environmental fidelity to arocky shore setting, including the immediately adjacent sedimentaryseafloor. The abundance of cemented bivalve species indicates that thefauna was well adapted to a high energy environment. This is similarto the environmental fidelity of the constructed hypothetical fossil as-semblage from Thailand, suggesting that a comparison between theCampanian and the constructed hypothetical fossil assemblages fromthe modern fauna is meaningful.

4.3. Comparison between the modern and the Campanian examples

Comparison of the modern and Campanian examples allows someinferences to be drawn concerning the original composition of the an-cient life assemblage. The modern rocky shore in Thailand was chosenas it is similar to the Campanian rocky shore with respect to climateand substrate type but there are clearly differences in local topography,current systems, wave action, and nutrient supply. The many differentlife forms, such as cementing bivalves and clinging but mobile gastro-pods, and faunal groups, such as barnacles, which are found at modernrocky shores, were also present at the Campanian rocky shore, showingthat a relatively high rocky shore species richness was established al-ready at this time (Fig. 1). Themodern species in Fig. 1 (1–3) show sim-ilar morphological features and probably had similar mode of lives astheir ancient counterpart which belong to the same families (Fig. 1D, I,and J respectively). The inferred high rocky shore species richness is incontradiction to Johnson and Baarli (2012) who suggested a relativelylower richness of rocky shore faunas during the Late Cretaceous(Table 2). It is assumed that most species from the Swedish rockyshore were actual inhabitants of this environment, with only few spe-cies out-of-habitat. This similarity in species richness, life forms, andphysical conditions of the rocky shores underlines the usefulness incomparing the modern and ancient shelly mollusc faunas.

The taxonomic agreement between a life and a future fossil assem-blage is low because there is a high loss of species from the life assem-blage even before onset of burial and fossilization as observed in themodern fauna from Thailand (Sørensen and Surlyk, 2013). This indi-cates that the taxonomic agreement between the ancient life assem-blage and the actual fossil assemblage may also have been low. Thecomposition of the original Campanian life assemblage can thus be dif-ficult to reconstruct, and the time averaging of many generations ofdeath assemblages with varying faunal composition, makes it evenmore difficult.

The modern life assemblage is dominated by gastropods, whereasthe constructed hypothetical fossil assemblage from Thailand and theCampanian fossil assemblage are both dominated by bivalves (Fig. 5).In the constructed hypothetical fossil assemblage from Thailand this re-flects the dissolution of aragonitic epifaunal gastropods and the post-mortemmix of the epifaunal rocky shore assemblage and the surround-ing sandy pocket beach assemblage (Sørensen and Surlyk, 2013). Theconstructed hypothetical fossil assemblage from Thailand and the

Table 1The shell-bearing modern life, death, and hypothetical fossil assemblages from Thailand, the Campanian rocky shore assemblage from Sweden, and the Cenomanian rocky shore assem-blage from Germany. The total numbers of species in each assemblage, bivalve and gastropod species, and of aragonitic, calcitic, epifaunal aragonitic, infaunal aragonitic, epifaunal calcitic,and infaunal calcitic species are shown. B = Bivalves, G = Gastropods.

Modern life assemblage Modern death assemblage Hypothetical fossil assemblage Late Cretaceous fossil assemblage Cenomanian fossil assemblage

Number of species 65 220 67 78 46Bivalve species 8 85 51 61 0Gastropod species 57 135 16 17 46Aragonitic species 60 195 42 29 45Calcitic species 5 25 25 46 0Epifaunal aragonite B = 7

G = 53 Total 60B = 34G = 119 Total 153

0 B = 2G = 7 Total 9

B = 0G = 40 Total 40

Infaunal aragonite 0 B = 38G = 4 Total 42

B = 38G = 4 Total 42

B = 17G = 3 Total 20

B = 0G = 5 Total 5

Epifaunal calcite B = 1G = 4 Total 5

B = 12G = 12 Total 24

B = 12G = 12 Total 24

B = 39G = 4 Total 43

0

Infaunal calcite 0 B = 1G = 0 Total 1

B = 1G = 0 Total 1

B = 3G = 0 Total 3

0

50 A.M. Sørensen, F. Surlyk / Palaeogeography, Palaeoclimatology, Palaeoecology 423 (2015) 44–52

Campanian fossil assemblage are similar with respect to species rich-ness and ratio between bivalves and gastropods (Fig. 5). By analogy itis suggested that the Campanian rocky shore fauna also experienced ahigh degree of aragonite dissolution of epifaunal gastropods and apost-mortemmix of the epifaunal rocky shore assemblage with the ad-jacent sediment seafloor assemblage.

A classic Late Cretaceous, Cenomanian rocky shore is exposed in theKassenberg quarry in Mülheim, Germany. It is known for its highly di-verse and well preserved macrofauna including aragonitic species. Therocky shore fauna occurs in a hard limestone, which was deposited incavities of Carboniferous sandstone (Kiel and Bandel, 2004). The depo-sition in cavities suggests that the limestone was protected againsthigh energies and that the cavities acted as preservation traps. Thefauna includes corals, brachiopods, echinoderms, bryozoans, spongesand cephalopods (e.g. Scheer and Stottrop, 1995). Furthermore, thefauna includes 46 gastropod species of which 45 can be assigned to arocky shore environment reflecting that gastropods were common in-habitants of rocky shores during the Late Cretaceous (Kiel and Bandel,2004). This corroborates the interpretation that an originally high-diversity gastropod fauna lived along the Campanian rocky shore, butis poorly represented in the fossil assemblage. Not only is the preservedgastropod richness interpreted as much lower than in the original lifeassemblage, but the fossil assemblage gives a completely misleadingidea of the original gastropod density. This is supported by the abundantpresence of boreholes in shells produced by non-preserved gastropodspecies.

The richness and the ratio between gastropod and bivalve speciesare similar between the Campanian assemblage and the constructedhypothetical fossil assemblage from Thailand (Fig. 5). However, thearagonite/calcite ratio is 29/42 in the preserved Campanian fauna and42/25 in the hypothetical fossil assemblage from Thailand. Theinfaunal/epifaunal ratio is 23/51 in the preserved Campanian faunaand 43/24 in the hypothetical fossil assemblage from Thailand. These

Table 2Number of species in different faunal groups along rocky shores during the Late Creta-ceous. The number shows that the Late Cretaceous rocky shore faunas is about two timesmore diverse than previously thought and thus had a relatively well established andadapted fauna. Worldwide rocky shore species numbers are based on Johnson and Baarli(2012), Swedish species numbers on Sørensen (2008), Sørensen and Surlyk (2010, 2011),Sørensen et al. (2011, 2012), Gale and Sørensen (2014, in press) andGerman species num-bers on Kiel and Bandel (2004).

LateCretaceousrocky shores

No. ofgastropodspecies

No. ofbivalvespecies

No. ofcirripedspecies

No. ofpolychaetespecies

No. ofechinodermspecies

Worldwide b10 56 N10 10 10Sweden 17 61 22 25 34Germany 46 0 0 0 0

values are almost the opposite of each other (Figs. 6, 7). The constructedhypothetical fossil assemblage fromThailand is dominated by aragoniticinfaunal species, whereas the preserved Campanian fossil assemblage isdominated by calcitic epifaunal species (Table 1). This is probably due toaragonite dissolution and time averaging of generations of death assem-blages in the Campanian assemblage, where generations of calcitic epi-faunal species have been preserved over hundreds and thousands ofyears, whereas the hypothetical fossil assemblage from Thailand is re-constructed from a single present-day death assemblage, i.e. one timeslice.

The hypothetical fossil assemblage from Thailand is constructed onthe assumption that all epifaunal aragonitic species were dissolved.This is not in full agreement with the Campanian fossil assemblage,which contains seven aragonitic epifaunal gastropod and two aragoniticepifaunal bivalve species. In modern settings dissolution of carbonate isless effective where burial is rapid and in shallow water, high energysettings where microbial dissolution is reduced (Powell et al., 2002;Cherns et al., 2011). This suggests that sedimentation rates were highalong the Campanian rocky shore, so that the epifaunal aragonitic shellswere buried before mechanical destruction or dissolution took place.This is in agreement with the relatively thick carbonate succession,more than 25 m, onlapping the clean gneiss surface over a short periodof geological time, represented by just one belemnite zone, indicatingcontinuous creation of accommodation space due to rapid sea-levelrise. However, the rarity of mouldic specimens of each aragoniticspecies indicates a high taphonomic loss of these species in spite ofrapid burial.

The environmental fidelity is high between the modern life anddeath assemblages from Thailand. The environmental fidelity betweenthe modern life and the constructed hypothetical fossil assemblagesfrom Thailand is also high, as the hypothetical fossil assemblage isbased on the death assemblage. An ancient fossil assemblage is time-averaged by generations of death assemblages, and out-of-habitattransportation is relatively unimportant. The fossil fauna found at an an-cient rocky shore localitymay thus be expected to show a high environ-mental fidelity to an original rocky shore fauna and most of theretrieved fossil species were actually living on the rocky shore withvery few species brought in from adjacent environments.

4.4. Reconstruction of the Campanian life assemblage based on thefossil assemblage

The gastropod faunas of Late Cretaceous rocky shores show a rela-tively high species richness, and the rarity of moulds after Campanianaragonitic species is due to taphonomic factors. The original Campanianepifaunal gastropod fauna is therefore estimated to have been aroundthree times richer than in the fossil assemblage based on comparisonwith the modern and the Cenomanian gastropod faunas. This gives a

51A.M. Sørensen, F. Surlyk / Palaeogeography, Palaeoclimatology, Palaeoecology 423 (2015) 44–52

total of 51 species, which is a little higher than the 46 species from theGerman Cenomanian rocky shore and a little lower than the 57 speciesin the modern life assemblage from Thailand (Table 1).

The original Campanian epifaunal aragonitic bivalve faunawas prob-ably also richer than the fossil assemblage, where only two aragoniticepifaunal species have been found (3% of the bivalve fauna). Of themodern death assemblage from Thailand, 40% of the bivalve speciesare epifaunal aragonitic (=34 species), suggesting that the 3% of epifau-nal aragonitic bivalves at the Campanian rocky shore is probably a verylow estimate (Table 1). The Campanian epifaunal calcitic bivalve faunais probably richer than the original fauna at any time, as it is richerthan both the modern life and death assemblages from Thailand. Thisis interpreted to reflect the time averaging of generations of epifaunalcalcitic bivalves, and the good preservation potential of calcite. Thefavouring of calcite precipitation in the Cretaceous calcitic seas probablyhad little effect on the rocky shore fauna as the aragonitic abundance isrelatively high along the shores.

Many small delicate species and juveniles of certain species live inthe high energy zones along the modern rocky shore in Thailand(Sørensen, 2012; Sørensen and Surlyk, 2013). Similar species are notfound in the Campanian high energy zones, but small delicate speciesand juveniles are preserved in protected areas underneath boulders.These species were lost elsewhere along the rocky shore, probably dueto post-mortem transport and mechanical destruction.

The Campanian gastropod fauna and epifaunal aragonitic bivalvefauna are thus interpreted as having been much richer than the actualfossil assemblage. In contrast, the calcitic bivalve species are overrepre-sented compared to the original fauna, due to time averaging. The orig-inal Campanian fauna has thus experienced a change in the faunalcomposition from a gastropod-dominated life assemblage to a bivalve-dominated fossil assemblage due to dissolution of aragonite and excel-lent preservation of calcite. A study of life and death assemblages ofmodern rocky shores allows important inferences to be drawnconcerning interpretation of the taphonomic losses in an ancientrocky shore fauna and increase thefidelity in reconstructing the originalshelly invertebrate fauna.

5. Conclusions

• The Campanian rocky shoremollusc fauna shows high environmentalfidelity with a rocky shore environment and immediate adjacent sed-imentary sea floor with only one out-of-habitat species. By analogywith a modern and a Cenomanian rocky shore fauna it is inferredthat an originally high-diversity gastropod faunawas part of the Cam-panian rocky shore assemblage but is poorly represented. The gastro-pod shells have experienced a high degree of aragonite dissolution, asindicated by the presence of numerous boreholes made by non-preserved gastropod species.

• The rarity of moulds after aragonitic species at the Campanian rockyshore could be due to taphonomic processes and not to lower richnessof these species.

• The high richness of calcitic species in the Campanian fauna isinterpreted as a result of time averaging and a low loss by taphonomicprocesses.

• The original Campanian fauna is interpreted to have experienced achange in faunal composition froma gastropod-dominated life assem-blage to a bivalve-dominated fossil assemblage due to dissolution ofaragonite and excellent preservation of calcite.

• A study of life and death assemblages from a modern rocky shoregreatly increases the fidelity of the reconstruction of the shelly inver-tebrate fauna of an ancient example.

Acknowledgements

The study was supported by the Carlsberg Foundation and theNatural Science Faculty of the University of Copenhagen. Peter Alsen is

thanked for comments on an early manuscript version. We are gratefulto Markes E. Johnson and an anonymous reviewer for constructive andthoughtful comments which greatly improved the manuscript.

References

Behrensmeyer, A.K., Kidwell, S.M., Gastaldo, R.A., 2000. Taphonomy and paleobiology. In:Erwin, D., Wing, S. (Eds.), Deep Time, Paleobiology's Perspective. Paleobiology 26,pp. 103–147.

Best, M.M.R., Kidwell, S.M., 2000. Bivalve taphonomy in tropical mixed siliciclastic-carbonate settings. II. Effect of bivalve life habits and shell types. Paleobiology 26,103–115.

Bromley, R.G., 1981. Concepts in ichnotaxonomy illustrated by small round holes inShells. In: Martinell, J. (Ed.), Concepts and Methods in Paleontology. Acta GeólogicaHispánica 16, pp. 55–64.

Cherns, L., Wright, V.P., 2000. Missing molluscs as evidence of large-scale, early skeletalaragonite dissolution in a Silurian sea. Geology 28, 791–794.

Cherns, L., Wright, V.P., 2009. Quantifying the impacts of early diagenetic aragonite disso-lution on the fossil record. Palaios 24, 756–771.

Cherns, L., Wheeley, J.R., Wright, V.P., 2011. Taphonomic bias in shelly faunas throughtime: early aragonitic dissolution and its implications for the fossil record. In:Allison, P.A., Bottjer, D.J. (Eds.), Taphonomy: Process and Bias through Time. Topicsin Geobiology 32. Springer Science, pp. 79–105.

Christensen, W.K., 1975. Upper Cretaceous belemnites from the Kristianstad area inScania. Fossils Strata 7, 1–69.

Gale, A.S., Sørensen, A.M., 2014. Origin of the balanomorph barnacles (Crustacea,Cirripedia, Thoracica)—new evidence from the Late Cretaceous (Campanian) ofSweden. J. Syst. Palaeontol. http://dx.doi.org/10.1080/14772019.2014.954824.

Gale, A.S., Sørensen, A.M., 2015. Taxonomy and palaeoecology of thoracican cirripedes(Crustacea) from a Campanian rocky shoreline at Ivö Klack, southern Sweden. Cretac.Res. (in press).

Hancock, J.M., 1976. Petrology of the chalk. Proc. Geol. Assoc. 86, 499–535.Johnson, M.E., Baarli, B.G., 1999. Diversification of rocky-shore biotas through geologic

time. Geobios 32, 257–273.Johnson, M.E., Baarli, B.G., 2012. Development of intertidal biotas through Phanerozoic

time. In: Talent, J.A. (Ed.), Earth and Life; Global Biodiversity, Extinction Intervalsand Biogeographic Pertubations Through Time. Springer, pp. 63–128.

Kidwell, S.M., Flessa, K.W., 1996. The quality of the fossil record: populations, species, andcommunities. Annu. Rev. Earth Planet. Sci. 24, 433–464.

Kiel, S., Bandel, K., 2004. The Cenomanian Gastropoda of the Kassenberg quarry inMülheim (Germany, Late Cretaceous). Paläontol. Z. 78, 103–126.

Kominz, M.A., Browning, J.V., Miller, K.G., Sugarman, P.J., Mizintseva, S., Scotese, C.R., 2008.Late Cretaceous to Miocene sea-level estimates from the New Jersey and Delawarecoastal plain coreholes: an error analysis. Basin Res. 20, 211–226.

Lazo, D.G., 2004. Bivalve taphonomy: testing the effect of life habits on the shell conditionof the littleneck clam Protothaca (Protothaca) staminea (Mollusca: Bivalvia). Palaios19, 451–459.

Limpsaichol, P., 1981. Environmental factors estimated at PMBC. Phuket Mar. Biol. Cent.Res. Bull. 28, 23–26.

Powell, E.N., Parsons-Hubbard, K.M., Callender, W.R., Staff, G.M., Rowe, G.T., Brett, C.E.,Walker, S.E., Raymond, A., Carlson, D.D., White, S., Heise, E.A., 2002. Taphonomy onthe continental shelf and slope: two-year trends—Gulf of Mexico and Bahamas.Palaeogeogr. Palaeoclimatol. Palaeoecol. 184, 1–35.

Scheer, U., Stottrop, U., 1995. Die Kreide am Kassenberg. In: Weidert, W.K. (Ed.),Klassische Fundstellen der Paläontologie 3. Goldschneck-Verlag, Korb, pp. 127–141.

Scoffin, T.P., Tudhope, A.W., Brown, B.E., Chansang, H., Cheeney, R.F., 1992. Patterns andpossible environmental controls of skeletogenesis of Porites lutea, South Thailand.Coral Reefs 11, 1–11.

Smith, A.G., Smith, D.G., Funnell, B.M., 1994. Atlas of Mesozoic and Cenozoic Coastlines.Cambridge University Press, Cambridge (99 pp.).

Sørensen, A.M., 2008. A palaeoecological reconstruction of a Late Cretaceous rocky shore,Ivö Klack, Sweden. Unpublished Ph.D. thesis, University of Copenhagen.

Sørensen, A.M., 2012. Distribution, diversity, and abundance patterns of intertidal benthicmolluscs on rocky shores (Phuket Island, Thailand). Thai. Nat. Hist. Mus. J. 6, 113–129.

Sørensen, A.M., Surlyk, F., 2010. Palaeoecology of tube-dwelling polychaetes on a LateCretaceous rocky shore, Ivö Klack (Skåne, southern Sweden). Cretac. Res. 31,553–566.

Sørensen, A.M., Surlyk, F., 2011. Taphonomy and palaeoecology of the gastropod faunafrom a Late Cretaceous rocky shore, Sweden. Cretac. Res. 32, 472–479.

Sørensen, A.M., Surlyk, F., 2013. Mollusc life and death assemblages on a tropical rockyshore as proxies for the taphonomic loss in a fossil counterpart. Palaeogeogr.Palaeoclimatol. Palaeoecol. 377, 1–12.

Sørensen, A.M., Floris, S., Surlyk, F., 2011. Late Cretaceous scleractinian corals from therocky shore of Ivö Klack, southern Sweden, including some of the northernmostzooxanthellate corals. Cretac. Res. 32, 259–263.

Sørensen, A.M., Surlyk, F., Jagt, W.M., 2012. Adaptive morphologies and guild structure ina high-diversity bivalve fauna from an early Campanian rocky shore, Ivö Klack(Sweden). Cretac. Res. 33, 21–41.

Sørensen, A.M., Surlyk, F., Lindgren, J., 2013. Food resources and habitat selection of a di-verse vertebrate fauna from the upper lower Campanian of the Kristianstad Basin,southern Sweden. Cretac. Res. 42, 85–92.

Surlyk, F., Sørensen, A.M., 2010. An early Campanian rocky shore at Ivö Klack, southernSweden. Cretac. Res. 31, 567–576.

52 A.M. Sørensen, F. Surlyk / Palaeogeography, Palaeoclimatology, Palaeoecology 423 (2015) 44–52

Surlyk, F., Dons, T., Clausen, C.K., Higham, J., 2003. Upper Cretaceous. In: Evans, D.,Graham, C., Armour, A., Bathurst, P. (Eds.), The Millennium Atlas: Petroleum Geologyof the Central and Northern North Sea. Geological Society of London, pp. 213–224.

Tyson, R.V., Funnell, B.M., 1987. European Cretaceous shorelines, stage by stage.Palaeogeogr. Palaeoclimatol. Palaeoecol. 59, 69–91.

Wright, P., Cherns, L., Hodges, P., 2003. Missing molluscs: field testing taphonomicloss in the Mesozoic through early large-scale aragonite dissolution. Geology31, 211–214.

Ziegler, P., 1990. Geological Atlas of Western and Central Europe. Shell InternationaleMaatschappij B.V. (239 pp.).