The small theropod dinosaurs Tugulusaurus and Phaedrolosaurus from the early Cretaceous of Xinjiang, China

ABSTRACT

The type material of the small theropod dinosaurs Tugulusaurus faciles and Phaedrolosaurus ilikensis from the Lower Cretaceous (?Valanginian–Albian) Lianmugin Formation of Xinjiang, north-western China, is reviewed. Although based on an incomplete and rather poorly preserved specimen, Tugulusaurus can be shown to be valid on the basis of strongly broadened caudal vertebrae with an anteriorly placed neural arch and a short and highly asymmetrical metacarpal I. Phaedrolosaurus, based on an isolated tooth, must be considered a nomen dubium. A partial hind limb originally referred to this taxon can be demonstrated to be a distinct taxon of theropod on the basis of a posteriorly expanded fibular condyle on the proximal tibia and a longitudinal groove on the anterior side of the proximal end of the fibula. It is made the type of a new taxon, Xinjiangovenator parvus gen. et sp. nov. Whereas Tugulusaurus is the most basal coelurosaur known, Xinjiangovenator represents a maniraptoran.