A new crown-group salamander from the Middle Jurassic of Western Siberia, Russia

Abstract

A new crown-group salamander, Kiyatriton krasnolutskii sp. nov., from the Middle Jurassic (Bathonian) Itat Formation of the Berezovsk Quarry locality in Western Siberia, Russia, is described on the basis of new material and a dentary fragment previously referred to the undescribed salamander taxon “Berezovsk salamander B” (sensu Skutschas2013). Kiyatriton krasnolutskii sp. nov. differs from K. leshchinskiyi (type species of the genus Kiyatriton) in that the ventrolateral ridges on the atlas are sharper anteriorly, more ventrally oriented and reach the anterior cotylar rims and that the dentary has a relatively taller dental parapet. Kiyatriton krasnolutskii sp. nov. is one of the oldest salamanders in the fossil record. The finding of Kiyatriton krasnolutskii sp. nov. in Berezovsk Quarry is significant for: (1) clarifying that the previously reported “Berezovsk salamander B” is a crown-group salamander of the genus Kiyatriton; (2) extending the stratigraphic range of the genus Kiyatriton backward some 40 million years into the Bathonian, from the previously youngest record in the Aptian–Albian; (3) indicating that K. leshchinskiyi from the Aptian–Albian Shestakovo locality in Western Siberia, Russia, survived as a relic into the Early Cretaceous of present-day Western Siberia; (4) supporting the hypothesis that Bathonian vertebrate faunas of Europe and Western Siberia were homogeneous; and (5) suggesting that all Bathonian crown-group salamanders in Asia could be members of one cryptobranchoid clade and could represent the first radiation of Cryptobranchoidea.