Allosaurus

Allosaurus is one of the most famous and thoroughly studied carnivorous dinosaurs of all time. Dominating Late Jurassic North America and western Europe around 150 million years ago, this apex hunter averaged eight to nine metres in length. It possessed a large skull adorned with low crests in front of its eyes, muscular jaws armed with dozens of serrated teeth, and strong forelimbs bearing three curved claws. Rather than exerting enormous crushing force, its skull acted like a lightweight hatchet, delivering slashing bites to weaken prey. Fossil evidence shows that Allosaurus tackled formidable herbivores, including Stegosaurus and diplodocid sauropods, with healed puncture wounds and tail spike impacts documenting these intense prehistoric clashes.

Cleveland-Lloyd Dinosaur Quarry in Utah has yielded thousands of Allosaurus bones from dozens of individuals.

Where and when

Allosaurus lived in the Late Jurassic, from 155 to 145 million years ago (Kimmeridgian-Tithonian age). Its remains come from United States and Portugal, in the Morrison Formation.

The numbers

Length 9.1 m (estimates run from 8.5 to 9.7 m). Mass about 1.9 t. Hip height about 2.7 m. That is 5.4 human-lengths, or 0.81 of a double-decker bus. These are estimates from near-complete skeleton; fields marked estimated by the site are length, mass, hip height.

Compare Allosaurus with a bus Place on the timeline