Bulletin 51

New Mexico Museum of Natural History & Science

A Division of the

DEPARTMENT OF CULTURAL AFFAIRS

Crocodyle tracks and traces

edited by

Jesper Milàn, Spencer G. Lucas,Martin G. Lockley and Justin A. Spielmann

Albuquerque, 2010

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Milàn, J., Lucas, S.G., Lockley, M.G. and Spielmann, J.A., eds., 2010, Crocodyle tracks and traces. New Mexico Museum of Natural History and Science, Bulletin 51.

COPROLITES FROM THE DANIAN LIMESTONE(LOWER PALEOCENE) OF FAXE QUARRY, DENMARK

JESPER MILÀN

Geomuseum Faxe/Østsjællands Museum, Østervej 2, DK-4640 Faxe, Denmark and Department of Geographyand Geology, University of Copenhagen, Øster voldgade 10, DK-1350 Copenhagen K. Denmark; e-mail: jesperm@oesm.dk

Abstract—A collection of coprolites found in the Danian (Lower Paleocene) limestone of Faxe Quarry, Denmark,is described and attributed to the respective producers. Small, drop-like specimens with weak signs of spiral coilingare attributed to fish. Larger, heteropolar, spirally-coiled specimens are attributed to sharks, and large, cylindricalcoprolites with longitudinal striations on the surface are identified as crocodile coprolites. Fish and sharks areknown from abundant finds of otoliths and teeth in Faxe Quarry, and crocodiles are known from finds of singlebones and teeth.

INTRODUCTION

Faxe Limestone Quarry, situated in the southeastern part ofZealand, Denmark (Fig. 1), is world famous for its Danian, well-pre-served deep-water coral mounds and highly diverse invertebrate fauna(Bernecker and Weidlich, 1990, 2005; Willumsen, 1995; Surlyk andHåkansson, 1999; Graversen, 2001). Furthermore, the Faxe Quarry, to-gether with the nearby sea-cliff, Stevns Klint, is the type locality for theDanian Stage (Desor, 1847).

Faxe is situated in the Danish-Polish trough, which is bounded tothe south by the Ringkøbing-Fyn structural high and to the north by theFennoscandian shield (Fig. 1) (Surlyk and Håkansson, 1999). In additionto the extensive invertebrate fauna (Graversen, 2001), vertebrates arerepresented by 13 species of marine fish (Schwarzhans, 2003), 15 spe-cies of sharks (Jan Schultz Adolfssen, pers. comm, 2009) and crocodiles(Bonde et al., 2008). Further evidence of vertebrates is found in the formof polished quartz pebbles interpreted as gastroliths (Noe-Nygaard, 1975).Here, I describe a number of coprolites from the collections of GeomusemFaxe/Østsjællands Museum (10006-19, 10006- 58 and 10006-59) and ofthe private collectors Alice and Henning Rasmussen, Faxe, and assign the

coprolites to their respective producers.

COPROLITES

The coprolites were all collected in Faxe Quarry around 1998when an extremely fossil-rich layer was temporarily exposed. A total of49 coprolites were examined, but many were too fragmentary or erodedto be identified as more than just coprolites. However, 11 specimensranging from 11 to 26 mm long are sufficiently well-preserved to beidentified. Based on their external morphology, the coprolites are dividedinto three general morphotypes: One type consists of small, 11 to 14mm long, spherical to drop-like coprolites, with small, pointed ends. Thesurface is smooth, and the coprolite appears to be composed of numer-ous thin layers. There are weak signs of spiral coiling at the pointed endsof the coprolites (Fig. 2).

A second group consists of heteropolar, spiral coprolites with anirregular surface. They are composed of several layers “wrapped” irregu-larly around each other, giving the coprolite the superficial appearance ofa pine-cone. They measure 14 to 23 mm long and have a maximumdiameter of 11 mm (Fig. 3). A broken specimen shows the internal coiling

FIGURE 1. Faxe Limestone Quarry is located in the southeastern part of Denmark. Location map modified from Schnetler et al. (2001).

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to consist of six mm-thin layers tightly wrapped around each other (Fig.3D).

The last type is large coprolites, cylindrical in cross section, andwith diameters of up to 24 mm (Fig. 4). The surface of the coprolites issmooth, with occasional longitudinal striations (Fig. 4D). All the exam-ined specimens seem to be broken fragments of longer specimens, andthe unbroken ends of the coprolites are rounded, as they have beenterminated by constriction. Some of the broken surfaces show the copro-lites to be composed of concavo-convex units (Fig. 4A). One specimenhas preserved the partly dissolved remains of an indeterminate fish ver-tebra (Fig. 4E-F).

FIGURE 2. A-C, small drop-like coprolites, probably from fish. A, Geomuseum Faxe no. 10006-58. Scale bar = 1 cm.

FIGURE 3. Heteropolar, spirally-coiled coprolites from sharks. A-B,Complete specimens showing clear coiling of the surface. A, GeomuseumFaxe no. 10006-59. C, Specimens that are broken in half. D, The brokensurface of C, shows the internal coiling of the specimen. All specimensshown to same size. Scale bar = 1 cm.

DISCUSSION

All the coprolites collected in Faxe Quarry are in excess of 5 mmin total length. This excludes most invertebrates as producers, as theirfecal pellets normally are less than 5 mm long (Häntzschel et al., 1968).The vertebrate fauna from Faxe Quarry consists of 13 species of fish(Schwarzhans, 2003) and 15 species of sharks. Size-wise, the sharksranged from 0.5 to 5 meter long (Jan Schultz Adolfssen, pers. comm.2009). Crocodilian body remains from Faxe are known from two finds ofbones, a basioccipital and a cervical vertebra, both stored in the collectionof the Geological Museum of the Natural History Museum of Denmark(Bonde et al., 2008), and several loose teeth from the collection ofGeomuseum Faxe/Østsjællands Museum and private collectors. A com-plete skull and a partial upper jaw were described from the similar-agedLimhamn Quarry in Malmø, southern Sweden, as Thoracosaurus scanicus(Troedsson, 1923, 1924).

Spiral-shaped coprolites are generally attributed to fish having aspiral valve (Hunt et al., 1994; Sumner, 1994; Northwood, 2005), andthe heteropolar spiral coprolites are attributed to sharks, due to theirmore complex valves (McAllister, 1985). The large coprolites are allelongated and cylindrical to slightly flattened in cross-section. This is ashape commonly found in crocodylian coprolites of all ages, fossil andrecent (Young, 1964; Sawyer, 1981; Thulborn, 1991; Souto, this volume;Milàn & Hedegaard, this volume), and it is a general shape for fossil(Chin, 2002) and modern animals having a diet similar to that of crocodil-ians (Chame, 2003; Stuart and Stuart, 1998). The presence of a recogniz-able fish vertebra in one of the specimens (Fig. 4E-F), suggest that itoriginated from another animal, as the digestion system of crocodilestend to decalcify and dissolve bone tissue before it is excreted (Fischer,1981). The concave endings of some of the coprolite specimens (Fig. 4A)are consistent with that of Cretaceous crocodile coprolites from Brazil(Souto, this volume), and what is observed in recent crocodile faeces(Milàn and Hedegaard, this volume). Coprolites with longitudinal stria-tions on their surface have been described from Paleocene coprolitesattributed to crocodiles and in recent crocodile fecal pellets (Young, 1964),as well as in Cretaceous specimens (Rodríguez-de la Rosa et al., 1998).Northwood (2005) discusses longitudinally striated coprolites and at-tributes them to archosauromorphs. Crocodiles are the only archosaursknown from the fossil record of the Danian limestone of Faxe Quarry,and are thus the most likely producers of the large coprolites.

CONCLUSION

Three different types of coprolites are described from the Danianlimestone in Faxe Quarry. Small drop-like coprolites are attributed toindeterminate fish, and larger, spirally-coiled specimens are identified asshark coprolites. Large cylindrical coprolites, with longitudinal stria-tions on the surface and a content of fish remains, are identified ascrocodile coprolites. This is the first record of crocodilian coprolitesfrom Denmark.

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ACKNOWLEDGMENTS

The research of JM is supported by the Danish Natural ScienceResearch Council. I am grateful to Alice and Henning Rasmussen for

FIGURE 4. Large cylindrical crocodile coprolites. A-C, large specimens, that are all fragments of longer coprolites. The unbroken ends are rounded. B,Geomuseum Faxe no. 10006-19. D, Coprolite showing longitudinal striations preserved in parts of the surface, indicated by arrows. E, Coprolite containinga partially dissolved vertebra from a fish. This coprolite might not have been produced by a crocodile. F, Close-up of the fish vertebra in E. A-E arereproduced to the same scale. Scale bar = 1 cm.

making their coprolites available for scientific investigations. The criticalreviews by Richard G. Bromley and Paulo Souto helped to improve themanuscript significantly.

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