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

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.