The last of them? A new relic karaurid stem salamander from the Lower Cretaceous of Western Siberia, Russia

Abstract

A new karaurid stem salamander, Kuzbassia sola gen. et sp. nov., from the Lower Cretaceous (Aptian) Ilek Formation of Shestakovo 1 locality in Western Siberia, Russia, is described on the basis of isolated vertebrae, including incomplete atlantal and trunk vertebral centra. The new taxon is diagnosed by the following unique combination of vertebral characters: the presence of a shallow dorsolateral depression and low ridges (longitudinal, vertical and oblique ridges) flanking this depression on the lateral surface of the atlantal centrum; the absence of deep lateral grooves or depressions on the lateral surfaces and ventral depression on the ventral surface of the atlantal centrum; the absence of ventro-lateral ridges, transverse processes and alar processes associated with the transverse processes on the atlantal centrum; anterior cotyles with elliptical anterior outline, located at an angle of approximately 150–160 degrees to each other; and the presence of a pair of rugose surfaces with low tubercles (= ?anterior basapophyses) on the ventral surface of the anterior portion of the trunk vertebral centrum. Kuzbassia sola gen. et sp. nov. is the last karaurid salamander in the fossil record to date.