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The Allosaurus has a name that literally means the other lizard. Possibly this was due to the fact that the first bones were discovered during the bone wars between Edward Cope and Othniel Marsh during the late 19th century in Wyoming and Colorado. What started as competition for prestige degenerated into a bitter feud where employees of both scientists staged attacks on each other. Dinosaur bones were destroyed though underhanded means, with theft and bribery rife. When success was measured in the weight of bones found, is it any wonder that that the Allosaurus simply became the other lizard?.  

A guess of what the Allosaurus looked like

Physical Description

Allosaurs had short strong necks and a deep narrow body. The genus is characterised by two bony horns in front of the eyes and two lumps behind. These lumps and bumps were probably highly coloured and when set upon a muscle bound beast that could reach twelve meters in length, five meters in height and possibly weighing up to two tonnes would crown a quite formidable creature. Its eyes were relatively widely spaced so its binocular vision and depth perception cannot have been particularly keen. Despite this, the allosaurous was a winning formula; a perfect predator for prey that were growing ever biger.

Their arms were strong but short and both the arms and the legs would have had three toes.  Allosaurus like all carnosaurs had large curved serrated teeth and a powerful bite.  These teeth were replaced throughout the allosaurouses life and these fossil teeth are often found with the skeletons of herbivorous dinosaurs of the day such as sauropods and stegosaurs. Its skull is relatively small for a predator of its size measuring only about 9 cm, however this may have allowed it to sprint much faster than its heavier headed cousins. As is the case with nearly all reptiles the Allosaurs would have laid eggs. It is not thought that Allosaurs lingered near the nest to protect or feed their young. 


An allosaurus to scale


The Allosaurus was an active predator. This is known because Allosaurus bite marks have been found in the bones of prey with evidence of healing, indicating that the prey had managed to escape. This means that the Allosaurus attacked living creatures, rather than scavenging meals from dead ones. How the prey managed to escape alive with such injuries from such a vicious predator is another matter; possibly some other  member of the herd was eaten instead. Another possibility is that the attacking allosaur became a victim of its intended meal; many predators of the age have been found with crushed bones from the strike of a stegosauruses sledgehammer blow, or from a sauropods whip like tail. 

Here is a video of an allosaurus:



Allosauruses were the top predators of North America in the late Jurassic (similer species lived in Africa and Australia and their bones are amazingly common for a predator.  Hundreds of skeletons have been found some of which have been like big Al amazingly preserved (compare this to the fact that less than 20 sets of bones have been found of the much more popular Tyrannosaurus).  The Allosaurus is certainly a fabulous beast.




Did you know?

Until age 15, an Allosaurus would grow approximately 330 lbs per year.

Even with such a large head, the bite force of an Allosaurus was less than that of an alligator or even lion 

The Allosaurus was the top predator in Sir Arthur Conan Doyle's novel, The Lost World 


Kingdom: Animalia

Phylum: Chordata

Class: Sauropsida

Order: Saurischia

Family: Allosauridae

Genus: Allosaurus


  • A. fragilis Marsh, 1877 (type)
  • A. europaeus Mateus et al., 2006
  • A. “jimmadseni” Chure, 2000 vide Glut, 2003 (nomen nudum)
  • A. tendagurensis Janensch, 1925



La disparition des dinosaures