Marshosaurus
Encyclopedia
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"
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.
, but none were found.
Theropoda
Theropoda is both a suborder of bipedal saurischian dinosaurs, and a clade consisting of that suborder and its descendants . Dinosaurs belonging to the suborder theropoda were primarily carnivorous, although a number of theropod groups evolved herbivory, omnivory, and insectivory...
, 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
Morrison Formation
The Morrison Formation is a distinctive sequence of Late Jurassic sedimentary rock that is found in the western United States, which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltstone and limestone and is light grey, greenish...
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
Othniel Charles Marsh
Othniel Charles Marsh was an American paleontologist. Marsh was one of the preeminent scientists in the field; the discovery or description of dozens of news species and theories on the origins of birds are among his legacies.Born into a modest family, Marsh was able to afford higher education...
, who described many dinosaur fossils during the Bone Wars
Bone Wars
The Bone Wars, also known as the "Great Dinosaur Rush", refers to a period of intense fossil speculation and discovery during the Gilded Age of American history, marked by a heated rivalry between Edward Drinker Cope and Othniel Charles Marsh...
. The species name was chosen "in honor of the bicentennial of the United States of America"
Characters on the skeleton show it was an avetheropod, a member of Avetheropoda, a group of more bird-like theropods including Tyrannosaurus
Tyrannosaurus
Tyrannosaurus meaning "tyrant," and sauros meaning "lizard") is a genus of coelurosaurian theropod dinosaur. The species Tyrannosaurus rex , commonly abbreviated to T. rex, is a fixture in popular culture. It lived throughout what is now western North America, with a much wider range than other...
, Velociraptor
Velociraptor
Velociraptor is a genus of dromaeosaurid theropod dinosaur that existed approximately 75 to 71 million years ago during the later part of the Cretaceous Period. Two species are currently recognized, although others have been assigned in the past. The type species is V. mongoliensis; fossils...
and Allosaurus
Allosaurus
Allosaurus is a genus of large theropod dinosaur that lived 155 to 150 million years ago during the late Jurassic period . The name Allosaurus means "different lizard". It is derived from the Greek /allos and /sauros...
. Benson (et al., 2009) found it to be a megalosauroid, using a lot of new characters of new Megalosaurus
Megalosaurus
Megalosaurus is a genus of large meat-eating theropod dinosaurs of the Middle Jurassic period of Europe...
specimens. It lived during the Kimmeridgian
Kimmeridgian
In the geologic timescale, the Kimmeridgian is an age or stage in the Late or Upper Jurassic epoch or series. It spans the time between 155.7 ± 4 Ma and 150.8 ± 4 Ma . The Kimmeridgian follows the Oxfordian and precedes the Tithonian....
(Late Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
), approximately 155 - 150 mya.
Paleopathology
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. In a 2001 study conducted by Bruce Rothschild and other paleontologists, 5 foot bones referred to Marshosaurus were examined for signs of stress fractureStress fracture
A stress fracture is one type of incomplete fracture in bones. It is caused by "unusual or repeated stress" and also heavy continuous weight on the ankle or leg...
, but none were found.