Marshosaurus
Name:
Marshosaurus
(Marsh’s lizard).
Phonetic: Marsh-o-sore-us.
Named By: James Madsen - 1976.
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Theropoda, Megalosauroidea.
Species: M. bicentesimus
(type).
Diet: Carnivore.
Size: Estimated bertween 5 and 6 meters
long, Skull 0.6 meters long.
Known locations: Utah, Colorado - Morrison
Formation.
Time period: Kimmeridgian of the Jurassic.
Fossil representation: At least three individuals
with possible further remains.
In
terms of size Marshosaurus was a middle of the
range theropod but one
that seems built for strength. Aside from the fairly robust skull,
the short but thick humerus of the arms indicates that Marshosaurus
was adapted for holding onto and physically subduing its prey. A
right ilium (hip bone) of Marshosaurus is also
recorded as having a
deformity that was probably occurred through injury.
Marshosaurus
was named in honour of the Palaeontologist Othniel Charles Marsh who in
the nineteenth century was one of the most prolific describers of
prehistoric animals including some of the most famous ones today, all
while embroiled in a fierce rivalry with another Palaeontologist named
Edward Drinker Cope. Marsh would actually get another dinosaur named
after him in 2007 called Othnielosaurus. The
interesting thing
here is that Othnielosaurus was a small herbivorous
ornithopod dinosaur
that was also active at roughly the same time and locations as
Marshosaurus, and it’s not unreasonable to
speculate that
Marshosaurus may have on occasion hunted
Othnielosaurus. The type
species name of M. bicentesimus came about
because the USA was
celebrating two hundred years of existence in 1976.
Marshosaurus
is but one of the many theropod dinosaurs that have been discovered at
the Cleveland Lloyd Dinosaur Quarry, an area that is thought to have
been a huge predator trap back in the late Jurassic. Other theropods
here include Allosaurus
(the most common theropod here),
Ceratosaurus,
Ornitholestes,
Torvosaurus,
and Stokesosaurus.
In addition to these predators, other dinosaurs such as
Stegosaurus,
Brachiosaurus,
Camarasaurus
and Camptosaurus
are also
present in the Quarry. It is believed that these herbivores had
become stuck as they tried to cross mud flats that were present here.
Lured in by their distress calls and the smell of dead dinosaurs
that had succumbed to exhaustion, the meat eating dinosaurs came in
to feast upon the free bounty only to become trapped themselves.
Further reading
- A second new theropod dinosaur from the Late Jurassic of east central
Utah. - Utah Geology 3(1):51-60. - J. H. Madsen, Jr. - 1976.
- New data on the theropod Marshosaurus from the
Morrison Formation
(Upper Jurassic: Kimmeridgian-Tithonian) of Dinosaur NM. - D. Chure,
Brook Britt & James H. Madsen - 1993.
- A new specimen of Marshosaurus bicentesimus (Theropoda) from the
Morrison Formation (Late Jurassic) of Dinosaur National Monument. -
Journal of Vertebrate Paleontology. 17 (supp 3): 38A. - D. Chure, Brook
Britt & James H. Madsen - 1997.
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