Shuvosaurus inexpectatus (Chatterjee 1993 ) Synonyms: Chatterjeea elegans Long & Murry, 1995, Carnian, Late Triassic ~210 mya, was originally considered the oldest ornithomimid dinosaur, based on the toothless skull. Associating the skull-less post-cranial skeleton with the skull came after the discovery of a sister taxon, Effigia. Brusatte et al. (2010), among others, considered Shuvosaurus and a sister taxon, Lotosaurus, poposaurid rauisuchians related to Saurosuchus and Prestosuchus. Here Shuvosaurus nests with poposaurids descending from Turfanosuchus, Sacisaurus and Silesaurus.

Distinct from Silesaurus, the skull of Shuvosaurus was overall smaller and had no teeth. The rostrum was straighter. The cranium was lower than the orbit.

The cervicals were elongated. The entire vertebral column appears more gracile, but neural spines were not well preserved.

The scapula was more robust, especially ventrally, with a fused scapula/coracoid. The humerus was more gracile.

The ilium was slightly smaller, but the pubis extended further ventrally and terminated in a longer "boot." The ischium was more gracile. The hind limbs were more gracile. The calcaneal "heel" curled proximally. Metatarsal 1 was more slender than the others, but digit I was as robust as the others. Enormous unguals tipped the toes.

Most paleontologists place too much emphasis on the calcaneal "heel". It grew smaller in Silesaurus and Lotosaurus and larger in Effigia and Shuvosaurus.

Comparing the skulls of Effigia (left) and Shuvosaurus (right). The skull of Shuvosaurus here is based on a photo of the original material restored and differs somewhat from the original drawings (above).

Sillosuchus longicervix (Alcober and Parrish, 1997, Late Triassic, Argentina) compared to Shuvosaurus is the only poposaurid known outside of North America.

Alcober O, Parrish JM. 1997. A new poposaurid from the upper Triassic of Argentina. Journal of Vertebrate Paleontology 17:548–556

Brusatte SL, Benton MJ, Desojo JB and Langer MC 2010. The higher-level phylogeny of Archosauria (Tetrapoda: Diapsida), Journal of Systematic Palaeontology, 8:1, 3-47.

Chatterjee S 1991. An unusual toothless archosaur from the Triassic of Texas: the world's oldest ostrich dinosaur? Abstract, Journal of Vertebrate Paleontology, 8(3): 11A.

Chatterjee S 1993. Shuvosaurus, a new theropod: an unusual theropod dinosaur from the Triassic of Texas. National Geographic Research and Exploration 9 (3): 274–285.

Rauhut OWM 1997. On the cranial anatomy of Shuvosaurus inexpectatus (Dinosauria: Theropoda). In: Sachs, S., Rauhut, O. W. M. & Weigert, A. (eds) 1. Treffen der deutschsprachigen Palaeoherpetologen, Düsseldorf, 21.-23.02.1997; Extended Abstracts. Terra Nostra 7/97, pp. 17-21.

Long R and Murry P 1995. Late Triassic (Carnian-Norian) Tetrapods from the Southwestern United States. New Mexico Museum of Natural History and Science Bulletin 4, Pp. 153-163.

wiki/Shuvosaurus