Original paper

A choristoderan reptile from the Lower Cretaceous of Transbaikalia, Russia

Skutschas, Pavel P.

Abstract

New materials of the choristoderan reptile Khurendukhosaurus sp. are described from the Early Cretaceous Murtoi Formation, Transbaikalia. The Transbaikalian species is characterized by fused scapula and coracoid (uncertain polarity character) and such advanced features as a mediolaterally elongated marginal tooth bases, moderately laterally expanded basal tubera on the basioccipital, clavicular facets on the interclavicle that are continuous across the midline, closed vertebral notochordal canals and the absence of the ventromedial crest on dorsal vertebrae. The combination of derived states such as closed vertebral notochordal canals, the presence of small spinous processes below the presacral postzygapophyses, clavicular facets on the interclavicle that are continuous across the midline and the absence of the ventromedial crest on dorsal vertebrae, and primitive states such as closed neurocentral sutures; anteroposteriorly elongated neural spines with transversally expanded and rugose distal tips on dorsal vertebrae, elongated amphi- to platycoelus vertebral centra, and pronounced ventral longitudinal keels on the cervical vertebrae support the attribution of the Transbaikalian choristodere to Khurendukhosaurus. Phylogenetic analysis places Khurendukhosaurus in a one clade with the neochoristoderes, hyphalosaurids, Monjurosuchus and Lazarussuchus. The basal position of Khurendukhosaurus is not confirmed, nor is a referring of Khurendukhosaurus to the neochoristoderan family Simoedosauridae.

Keywords

choristoderakhurendukhosaurusphylogenyearly cretaceousasiatransbaikalia