Paleogene turtles of Eastern Europe: new findings and a revision

Abstract

The article provides an overview of all known 39 localities of the Paleogene turtles of Eastern Europe. Numerous remains of turtles are described for the first time from 19 localities, of which six are new, and 13 are the localities from which materials were only mentioned previously. Among them are Pan-Trionychidae indet., Pan-Cheloniidae indet., Dermochelyidae indet. and Pan-Testudines indet., as well as pan-cheloniids Argillochelys sp. from the Ypresian Novoivanovka and the Ypresian or Lutetian Gruzinov localities. Several indeterminate specimens from Eocene localities show similarity to pan-cheloniids Argillochelys cuneiceps (Owen, 1849) and Puppigerus camperi (Gray, 1831) or Tasbacka aldabergeni Nessov, 1987, and dermochelyids Natemys peruvianus Wood et al., 1996 or “Psephophorus” rupeliensis van Beneden, 1883. One specimen of costal 1 of Pan-Testudines indet. from the Lutetian Krasnorechenskoe locality resembles that of pleurodires Eocenochelus spp. and Neochelys spp. In addition, new materials of turtles are described from five previously known localities. Among them, new and additionally restored specimens from the Bartonian Ak-Kaya 1 locality of the pan-cheloniid Argillochelys sp., and the dermochelyid Cosmochelys sp., which expand data on their morphology and intraspecific variability. The specimens of pan-cheloniids with deep and dense sculpturing of the external shell surface from the Bakhmutovka, Bulgakovka, Krasnorechenskoe and Tripolye localities clearly belong to a new species, not described due to fragmentary material. It is supposed that Anhuichelys-like pan-testudinoids migrated from Asia in Eastern Europe in the Danian age, and were preserved as relict Dithyrosternon valdense Pictet et Humbert, 1855 until the Priabonian age.

A new Trachyaspis-like pan-cheloniid turtle from the Bartonian of Kazakhstan

“…In addition, the remains of sea turtles, referred to cf. Protrachyaspis sp., are also known from slightly older upper Lutetian deposits of the upper part of the Buchak -lower part of the Kiev formations on the northern periphery of eastern Tethys (Zvonok and Danilov 2023;Fig. 11).…”

“…The symphysis of the dentaries of Protrachyaspis shorymensis (ZIN PH 35/177) simultaneously has labial, symphyseal and lingual ridges, of which the labial A new Trachyaspis-like pan-cheloniid turtle The data on the stratigraphical distribution of pan-cheloniids is given according to the following sources: Ashleychelys palmeri, Osonachelus decorata, Puppigerus camperi, Trachyaspis lardyi (see Material and Methods section); Allopleuron hofmanni, Archelon ischyros, Calcarichelys gemma, Chelosphargis advena, Ctenochelys spp., Desmatochelys lowi, D. padillai, Protostega gigas, Rhinochelys pulchriceps and Toxochelys spp. (Danilov et al 2022); Cabindachelys landanensis, Eochelone brabantica, Erquelinnesia gosseleti, Tasbacka aldabergeni (Zvonok and Danilov 2023); Carolinochelys wilsoni, Pacifichelys spp. and Procolpochelys spp.…”