New material of Phuwiangvenator yaemniyomi (Dinosauria: Theropoda) from the type locality: Implications for the early evolution of Megaraptora

Phuwiangvenator yaemniyomi is a mid-sized, early branching megaraptoran theropod from the Lower Cretaceous Sao Khua Formation of Phu Wiang Mountain, Khon Kaen Province, northeastern Thailand. The holotype includes dorsal and sacral vertebrae, lower legs, hand and foot elements. Here we describe new skeletal material pertaining to the same individual representing the holotype of Phuwiangvenator based on size, shape, and shared phylogenetic affinities. This material was recovered at the same quarry as the holotype and consists of an incomplete fibula, left and right metatarsals. A new autapomorphy observed from the new material is the presence of a long, deep fossa between the lateral and medial distal condyles of the metatarsal II that extends to the distal articular facet is visible in anterior view. The metatarsal III of Phuwiangvenator is relatively short, more similar to the proportion present in basal carcharodontosaur Concavenator than in the derived megaraptorans, but more gracile than other basal allosauroids. Its hindlimb proportions are similar to the basal carcharodontosaur Neovenator than other more derived megaraptorans and coelurosaurs. Phuwiangvenator shows a combination of features shared with allosauroids and basal coelurosaurs and appears to be “intermediate” between non-megaraptorid and megaraptorid theropods. The present work adds anatomical data on this theropod and provides information on the early evolution of the Megaraptora.