Allosaurus
Allosaurus fragilis • "Different / Other Lizard"
Allosaurus was a large meat-eating theropod that lived in Late Jurassic North America. It had three-fingered hands and bony crests above its eyes; fossils with bite marks show it fed on other dinosaurs, including Stegosaurus.
- Length
- ≈9.7 m
- Weight
- ≈2.5 t
- Diet
- Carnivore
- Danger
- ★★★★★
Overview
The lion of the Jurassic period. Allosaurus was the top apex predator of its ecosystem, using its upper skull like a surgical battleaxe to slash deep wounds into Stegosaurus and massive sauropods.
“Over 12,000 Allosaurus bones have been recovered from the Cleveland-Lloyd Dinosaur Quarry in Utah alone, suggesting they may have hunted in packs or gathered at waterholes in large numbers.”
Key facts
Strengths
- Hatchet-style downward strike acceleration powered by massive neck muscles
- Coordinated pack hunting tactics capable of bringing down giant sauropods
- Superior stamina and sprint agility over heavier Jurassic herbivores
Weaknesses
- Lower jaw muscle force than tyrannosaurids
- Lighter skeletal frame susceptible to heavy blunt trauma from tail clubs or thagomizers
Natural weapons
- Hatchet-like jaw strike with kinetic upper skull drive
- Three-fingered grasping forelimbs with 20cm curved claws
- Dozens of backward-curving razor serrated slicing teeth
Movies vs. science
Myth: Portrayed as a mindless brute that bites with crushing force.
Reality: Allosaurus had a relatively light bite force, but used its massive neck muscles to drive its upper jaw into prey like a battleaxe.
Size & simulator stats
The Natural History Museum lists a length of about 9.7 m and an estimated mass of 2.7 tonnes; individual size varied.
- Length
- 9.7 m
- Height
- 3.2 m
- Weight
- 2.5 t
Illustrative simulator values (not measured biology)
See how Allosaurus measures up in the sourced size comparison chart.
Habitat
Seasonal floodplain woodlands, open river channels, and semi-arid scrublands.
North America; well-known fossils come from the western United States.
Diet
Hunted Stegosaurus, Camarasaurus, Diplodocus, and juvenile sauropods in packs.
Carnivore. Fossils with Allosaurus bite marks and other evidence indicate it ate dinosaurs, though hunting and scavenging likely both occurred.
Fossils & discovery
First described from United States, Portugal & Tanzania in 1877 (Cleveland-Lloyd Dinosaur Quarry, Morrison Formation).Over 12,000 Allosaurus bones have been recovered from the Cleveland-Lloyd Dinosaur Quarry in Utah alone, suggesting they may have hunted in packs or gathered at waterholes in large numbers.
Research sources
Sources checked on by the Dinosaurs Names Editorial Team. Editorial policy
Gallery
Related dinosaurs
Battle Arena
Can anything beat Allosaurus?
Send Allosaurus into an illustrative matchup against any other species and compare attack, defense, and bite force.
Fight as Allosaurus