| Marshosaurus Temporal range: Late Jurassic |
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|---|---|
| Reconstructed skull of Marshosaurus at the Carnegie Museum of Natural History | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Sauropsida |
| Superorder: | Dinosauria |
| Order: | Saurischia |
| Suborder: | Theropoda |
| (unranked): | Tetanurae |
| Superfamily: | Megalosauroidea[1] |
| Genus: | Marshosaurus |
| Species: | M. bicentesimus |
| Binomial name | |
| Marshosaurus bicentesimus Madsen, 1976 |
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Marshosaurus was a genus of medium sized theropod, with a size up to 5 or 6 meters (16 to 20 feet) in length and a skull about 60 cm (2 feet) long. It is known from parts of at least three (possibly four) individuals from the Morrison Formation of Utah and Colorado.
The holotype is a left ilium, or upper pelvis bone found at the Cleveland-Lloyd Quarry in central Utah. It was named by James Madsen (1976) for Othniel Charles Marsh, who described many dinosaur fossils during the Bone Wars. The species name was chosen "in honor of the bicentennial of the United States of America"[2]
Characters on the skeleton show it was an avetheropod, a member of Avetheropoda, a group of more bird-like theropods including Tyrannosaurus, Velociraptor and Allosaurus. Benson (et al., 2009) found it to be a megalosauroid, using a lot of new characters of new Megalosaurus specimens. It lived during the Kimmeridgian (Late Jurassic), approximately 155 - 150 mya.
One right ilium of a Marshosaurus bicentesimus is deformed by "an undescribed pathology" which probably originated as a consequence of injury. Another specimen has a pathological rib.[3] In a 2001 study conducted by Bruce Rothschild and other paleontologists, 5 foot bones referred to Marshosaurus were examined for signs of stress fracture, but none were found.[4]