The first record of a soft-shelled turtle (Testudines: Pan-Trionychidae) from southern Balkans (Pliocene, Gefira, N. Greece) and new information from bone histology

Abstract

Soft-shelled turtles (Pan-Trionychidae) are not included in the present-day chelonian fauna of Greece and have been unknown in the Greek fossil record up to now. Here we report the first fossil occurrence of a soft?shelled turtle from Greece, originating from the Pliocene Gefira Member (Angelochori Formation), in the lower Axios valley. The corresponding specimens were discovered with several mammalian remains, most of them attributable to the mastodon of Auvergne, Anancus arvernensis. The chelonian material includes five carapacial fragments that belong to the same individual and can be attributed to Pan-Trionychidae based on the typical sculpturing on the dorsal side of the carapace. Most of these bony plates were histologically sampled and thereby provide evidence for the ?plywood? structure, another characteristic of pan-trionychids. They represent the first extended sampling of trionychid plates that belong to the same individual, allowing the documentation of the variation of the relevant trionychid morphologies in the carapace. These findings expand the paleobiogeographic range of this taxon to the southern Balkans and Greece and allow a better estimation of the chelonian paleo-fauna of the area. They are also important for the temporal distribution of this clade in the Paleoarctic, as they join specimens from Italy as being the last trionychids in Europe.