Allosaurus Facts for Kids
AL-oh-SORE-us · its name means “different lizard”
The top meat-eater of the Jurassic, long before T. rex.
- 📏 28 ft8.5 m1 long
- ⚖️ weight: not yet checked
- 🕰️ 145 to 155 million years ago145 to 155 million years ago2
- 🍽️ meat
Allosaurus was a big meat-eater. It walked on two legs. It lived long before T. rex.
Allosaurus was the biggest hunter where Stegosaurus and Brontosaurus lived. It had small horns over its eyes and long arms with three sharp claws each. Many of its bones have been found in one quarry in Utah.
Allosaurus was the top predator of the Late Jurassic in North America, long, long before T. rex. The Cleveland-Lloyd Quarry in Utah holds so many Allosaurus bones that scientists have studied how they grew from babies to adults. Its arms were longer than T. rex's, with three clawed fingers.
Every dinosaur number is scientists’ best guess from bones, so each one says where it came from.
How big was Allosaurus?
Allosaurus in numbers
| Length (nose to tail) | 28 ft8.5 m1up to; scientists' estimate |
|---|---|
| Height at the hips | no checked number yet |
| Weight | no checked number yet |
| When it lived | 145 to 155 million years ago145 to 155 million years ago2about; the Late Jurassic |
| What it ate | other dinosaurs, such as Stegosaurus |
| Fossils found in | western North America, especially Utah, Colorado and Wyoming |
| What kind | a theropod: a two-legged dinosaur, the group birds came from |
Wow!
- It had small horns above its eyes.
- Its arms had three sharp claws each.
- One quarry in Utah is full of its bones.
🦴 Allosaurus’s bones
Books about Allosaurus, free at the library
Ask a grown-up to tap the button: it shows where to borrow a book about Allosaurus for free.
Where was the land back then?
The continents were in different places when Allosaurus lived, 145 to 155 million years ago. Open Planet Earth, pick Drifting continents, and slide back in time to see where the land was.
Its neighbours in time
Where these numbers come from
- National Park Service, Dinosaur National Monument: Allosaurus, checked 30 October 2026.
- Bureau of Land Management, Jurassic National Monument, checked 30 October 2026.
- Wikidata, Allosaurus (Q14400), checked 30 October 2026.
To read more: the Natural History Museum’s Dino Directory (see also, not copied).