Allosaurus

Allosaurus Temporal range: U.J.-L.K. 155–120 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Conservation status
Extinct
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Superorder:	Dinosauria
Order:	Saurischia
Suborder:	Theropoda
Family:	Allosauridae
Genus:	Allosaurus Marsh, 1877

Allosaurus was a large theropod dinosaur from the Jurassic period, a predatory carnivore.

Allosaurus averaged 8.5 metres (28 ft) in length, though some remains suggest it could reach over 12 meters (39 ft). Its three-fingered forelimbs were smaller than its large hind legs, and the body was balanced by a long, heavy tail.^[1] It weighed 2.3 tons.

It is the most common large predator found in the Morrison Formation of Colorado. This formation was laid down 155 to 145 million years ago, in the Jurassic.

Allosaurus was at the top of the food chain. It probably preyed on large herbivorous dinosaurs and perhaps even other predators, including Ceratosaurus and Marshosaurus. Potential prey included ornithopods, stegosaurs, and sauropods.

Some paleontologists think Allosaurus had cooperative behavior, and hunted in packs. Others believe they may have been aggressive toward each other.

Groups have been found together in the fossil record. This might be evidence of pack behavior, or just the result of lone individuals feeding on the same carcass.

Remains of many individuals have been found, including some which are almost complete. Over sixty-nine individuals from one species have been found.^[2]

1. ↑ Madsen, James H, Jr. 1993 [1976]. Allosaurus fragilis: a revised osteology. 2nd ed, Utah Geological Survey Bulletin 109. Salt Lake City: Utah Geological Survey.
2. ↑ Holtz, Thomas R., Jr.; Molnar, Ralph E.; and Currie, Philip J. 2004. Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds) The Dinosauria. 2nd ed, Berkeley: University of California Press. pp. 71–110. ISBN 0-520-24209-2