A new genus and species of basal salamanders from the Middle Jurassic of Western Siberia, Russia
A new basal stem salamander, <i>Urupia monstrosa </i>gen. et sp. nov., is described based on an atlantal centrum (holotype), fragments of trunk vertebrae, and some associated elements (fragmentary dentaries and a femur) from the Middle Jurassic (Bathonian) Itat Formation of Krasnoyarsk Territory in Western Siberia, Russia. The new taxon is characterized by the following combination of characters: lack of the spinal nerve foramina in the atlas, presence atlantal transverse processes and a deep depression on the ventral surface of the atlas; lateral surface of anterior part of the dentary is sculptured by oval and rounded pits; very short diaphyseal part of femur. The absence of intercotylar tubercle on the atlas and presence of atlantal transverse processes support for neotenic nature of <i>Urupia monstrosa </i>gen. et sp. nov. Large size, presence of sculpture on vertebrae, and the absence of spinal nerve foramina in the atlas suggest that <i>Urupia monstrosa </i>gen. et sp. nov. is a stem group salamander. The phylogenetic relationships of <i>Urupia monstrosa </i>gen. et sp. nov. with other stem group salamanders cannot be established on the available material.