Tiger shark feeding on sirenian – first fossil evidence from the middle Miocene of the Styrian Basin (Austria)

ABSTRACT

Based on a shark-bitten partial skeleton of an immature sirenian (Metaxytherium cf. medium) from the middle Miocene of the Styrian Basin (Austria), we report on the oldest predator–prey interaction between tiger sharks and dugongs. The bite mark-bearing ribs and vertebrae are associated with seven teeth of Galeocerdo aduncus, which are otherwise rare in the fossil record of the Styrian Basin. The unique tooth morphology of the genus Galeocerdo is reflected by an unambiguous pattern of bite marks, which is repeatedly detected on one rib fragment. Similar bite marks were reproduced experimentally by using clay instead of bone. The obtained pattern is consistent with the observed bite marks on the sirenian rib fragment, which demonstrates that tiger sharks fed upon the Metaxytherium carcass. Furthermore, we also report on the first record of the angel shark Squatina sp. within the Styrian Basin.

KEYWORDS:

• Galeocerdo
• metaxytherium medium
• elasmobranchs
• badenian
• Paratethys

Acknowledgments

Our sincere thanks to Gerhard Wanzenböck (Bad Vöslau) for the report on this sirenian remain as well as Martin Gross (Joanneum) and Lafarge-Perlmooser for assistance during fieldwork. We thank Norbert Winkler (Joanneum Graz, Austria) for the preparation of the specimen and Daryl P. Domning (Howard University, Washington, D.C.) for his help on sirenian anatomy. We also want to thank Jürgen Pollerspöck (Stephansposching, Germany) and Shark-References for providing literature and Monika Herold-Wagner (Brisbane, Australia) for linguistic improvement. We also thank A. Collareta (Università di Pisa, Italy), one anonymous reviewer, and the Handling Editor Gareth Dyke for providing helpful comments, which improved the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).