New material of Ulutrionyx ninae from the Oligocene of Kazakhstan, with a review of Oligocene trionychids of Asia

ABSTRACT

Six species of soft-shelled turtles (Trionychidae) have been previously described from the Oligocene of Asia. Four of those species were described based on fossils from the Turgai Depression and Zaisan (= Zaysan) Depression of Kazakhstan. We reevaluate those four species in light of new material from the Oligocene Chelkarnurinskaya Svita of the Turgai Depression. The new material is described and identified as Ulutrionyx ninae. Based on our revision, only two valid species of trionychid are present in the Oligocene of Asia. The relatively low diversity of Oligocene trionychids in Asia is mirrored by low trionychid diversity in North America during the same time period.

ACKNOWLEDGMENTS

We thank the two reviewers whose comments improved the manuscript. Financial support for research was provided by a grant from the President of the Russian Federation to the Leading Scientific Schools (NSh-2990.2014.4) and a grant of the Russian Foundation for Basic Research (no. 14-04-00416) to I.G.D. and a Geological Society of America graduate student research grant to N.S.V. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under grant no. DGE-1315138.

Handling editor: Patrick O'Connor.

Notes

¹ The direct translation of the word used in this description is ‘otic bone.’ It is unclear whether the author meant to refer to the prootic, opisthotic, or some other bone in the turtle skull.