A choristoderan reptile from the Lower Cretaceous of Japan

A new, small (c. 250 mm snout-vent length) choristoderan reptile, Shokawa i koi gen. et sp. nov., is described from the early Cretaceous Okurodani Form ation, Tetori Group, of Japan. It is distinguished from other known chorist oderans in having a long neck with at least 16 cervical vertebrae. The skel eton is pachyostotic and the caudal neural spines are much taller than thos e of the Jurassic Cteniogenys, both features suggesting a more aquatic life style. Phylogenetic analysis places the new Japanese form in a small clade with Cteniogenys and the Triassic Pachystropheus. This clade is the sister taxon of crown-group Neochoristodera.