Anatomy and relationship of Shuvosaurus, a basal theropod from the Triassic of Texas



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Shuvosaurus inexpectatus was initially discovered in 1993 and was determined to be either an ornithomimosaur or a basal theropod. Later research proposed that the Shuvosaurus skull belonged to the postcranial material of Chatterjeea, based on association and relative sizes, but no anatomical evidence was presented. Recent research reconfirmed that Shuvosaurus is a basal theropod based on cranial characters. A complete reconstruction of the skull was done to evaluate the proper phylogeny of Shuvosaurus. Individual elements of the skull show a strong resemblance to basal theropods including Syntarsus and Coelophysis. Cladistic analysis using the cranial anatomy confirms that Shuvosaurus fits firmly in the basal theropods adjacent to Syntarsus in the Coelophysoidea. An analysis of the skull and endocast of Shuvosaurus reveals a large secondary palate with a groove for a horny beak, a shortened snout, an enlarged orbit, an enlarged olfactory bulb, and an enlarged floccular fossa. The horny beak and shortened snout are similar to turtles and birds. Birds with this type of beak feed primarily on nuts. The enlarged orbit and olfactory bulb indicates it had exceptional smell and sight. The enlarged floccular fossa indicates a high level of activity associated with bipedalism.