Adocus Kohaku, A New Species of Aquatic Turtle (Testudines: Cryptodira: Adocidae) from the Late Cretaceous of Kuji, Iwate Prefecture, Northeast Japan, with Special References to the Geological Age of the Tamagawa Formation (Kuji Group) LSID urn:lsid:zoobank.org:act:61376EEE-A386-416E-98AE-FF64FE2597A2

Authors: Ren Hirayama*, Teppei Sonoda, Hikaru Uno, Kenji Horie, Yukiyasu Tsutsumi, Kazuhisa Sasaki, Shunsuke Mitsuzuka and Toshio Takisawa

Volume 4, Issue 1

Abstract

A nearly complete shell of the genus Adocus (Adocidae; Pan-Trionychia; Cryptodira; Testudines) was collected from the late Cretaceous (Turonian) Tamagawa Formation of Kuji Group at Kuji City, Iwate Prefecture, northeast Japan. This turtle shows unique features such as the loss of cervical scute, extreme expansion of marginal scutes overlying costal plates, and exclusion of the humeral- pectoral sulcus from entoplastron. Thus, A. kohaku is erected as a new species. As A. kohaku shows most derived position of A. kohaku within this genus, morphological diversity of the genus Adocus seems to have occurred rather early in its evolution in Eastern Asia.

Keywords: Adocus Kohaku sp. nov.; Cretaceous; Kuji Group; Reptilia; Testudines; U-Pb Dating

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