Allosaurus in a dry and sandy landscape

Allosaurus

Allosaurus were big, mean killing machines that reigned supreme during the late Jurassic period. They were the most common huge predators in North America 140 million years ago, reaching an impressive 12 metres in length and weighing up to four tonnes. These carnivorous dinosaurs could rip and tear chunks out of the large plant-eating sauropods and stegosaurs of the time. The enormous jaw was filled with long, serrated, back-curving teeth. Near perfect examples of this classic shaped theropod dinosaur were discovered in Wyoming and called Big Al and Big Al Two. Allosaurus fossil remains are extremely rare outside America.

Scientific name: Allosaurus

Rank: Genus

Watch video clips from past programmes (11 clips)

In order to see this content you need to have an up-to-date version of Flash installed and Javascript turned on.

View all 11 video clips

Allosaurus size

An illustration showing allosaurus's size relative to humans.

A comparison of allosaurus's size in relation to humans.

Behaviours

Discover what these behaviours are and how different plants and animals use them.

Additional data source: Animal Diversity Web

When they lived

Discover the other animals and plants that lived during the following geological time periods.

Jurassic period Jurassic period
The Jurassic began after the mass extinction event that ended the Triassic. Life, however, was quick to recover from this blow and the Jurassic eventually became host to the most diverse range of organisms that Earth had yet seen.

BBC News about Allosaurus

  • Who buys a dinosaur skeleton? The BBC's Olivia Lang reports on the trend of collecting dinosaur fossils, as Sothebys auction house puts a partially complete Allosaurus skeleton up for sale in Paris.

Video collections

Take a trip through the natural world with our themed collections of video clips from the natural history archive.

  • Deadly dinosaurs Deadly dinosaurs

    More dinosaurs have been discovered in the last two decades than the past 200 years.