Cheirogaster bacharidisi, sp. nov., a new species of a giant tortoise from the Pliocene of Thessaloniki (Macedonia, Greece)

ABSTRACT

In this paper, we describe a new species of a giant tortoise, Cheirogaster bacharidisi, sp. nov., from the Pliocene (Gonia Formation) of western Chalkidiki Peninsula, near Thessaloniki, Greece. The specimens constitute the most complete giant tortoise found to date in Greece, and provide materials for direct comparison with other described European forms. We assign it to the genus Cheirogaster, as opposed to Centrochelys, based upon the convex dorsal surface of the epiplastron. Direct comparison with material from Europe shows that it differs from other giant tortoises attributed to Cheirogaster mainly in cranial and plastral morphology. Exceptional postcranial preservation allows the description of many skeletal elements, previously unknown or poorly described for Cheirogaster, as well as for a reappraisal of the previously published specimens from Greece.

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ACKNOWLEDGMENTS

The authors express their sincere thanks to the researchers involved in the excavation and collection of specimens, especially N. Bacharidis, G. Lazarides, H. Luett, K. Chantzarides, A. Tzanoudakis, and A. Xanthis. We would like to thank G. Syrides and K. Vasileiadou for their help with stratigraphy; A. Pérez-García for valuable comments and information about Spanish material; and T. Kotsakis (Laboratorio di Paleontologia dei Vertebrati, Roma Tre). We thank F. de Lapparent de Broin for discussions on the material in the MNHN. Valuable comments from reviewers F. de Lapparent de Broin and M. Rabi (University of Tübingen) greatly improved the manuscript. S. Modesto is thanked for editorial work. For access to collections, we would like to thank G. Theodorou and S. Roussiakis (AMPG), M. Harzhauser and U. Göhlich (NHMW), R. Allain and B. Battail (MNHN), M. Moser (BSPG), H. Furrer (PIMUZ), and S. Scherrer (NWS).

Handling editor: Sean Modesto