Allosaurus

'Different Lizard'

Geologic Time: 145 to 150 million years ago (Late Jurassic)

Geographic Range: Wyoming, Montana, Colorado, New Mexico, South Dakota, Utah, and Oklahoma
Adult Weight: 1.5 - 2 tons

Adult Length: 30 - 40 ft long

Habitat: Plains and lowlands

Diet: Meat

Characteristics: Allosaurus was the most common large carnivore of the Late Jurassic in North America. It was a smaller predecessor of the Cretaceous Tyrannosaurus. Strong forelimbs with sharp claws, powerful hind legs and recurved, dagger-like teeth are evidence that Allosaurus was a formidable predator. Although it was much smaller than sauropods like Apatosaurus (Brontosaurus), which were also common at the time, quite possibly Allosaurus hunted in packs to bring down larger prey. Like many meat eaters, it may also have been a scavenger.

Many Allosaurus specimens representing individuals of different ages have been recovered in exposures of the Morrison Formation in the Rocky Mountain West. This specimen is interpreted as a subadult.