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Allosaurus

'Different lizard'

Walking with Dinosaurs - Allosaurus

Allosaurus was a large bipedal dinosaur with a huge skull balanced by a long and heavy tail. Being a large and powerful meat eater with formidable teeth and a savage bite, Allosaurus would have been top dog in its Jurassic ecosystem. It would have been quick enough to outrun its very slow prey.

They call it home

Allosaurus lived during the Late Jurassic and has been found primarily in North America's Morrison Formation, with a few fossils also known from Portugal. The Morrison Formation itself is a long stretch of ancient rock running from Montana, all the way to New Mexico. The rock formation allows us to step back in time to see a once verdant landscape of rivers, lakes, and vast plains – a perfect setting for such an awesome ecosystem.

What we heard about their hearing

What we heard about their hearing

Allosaurus had crocodile ears. It would have had poor hearing, only being able to hear low frequency sounds.


What big teeth you have

What big teeth you have

Allosaurus had backward facing teeth, which meant with each struggle, its hapless victim would be pushed further down the dinosaur's huge throat.

Nose knowledge

Nose knowledge

Allosaurus had a well-developed sense of smell, useful for sniffing out its prey.



The poop scoop

The poop scoop

Allosaurus droppings have been found to be 1.52m (nearly 5ft) in length and 10.2cm (4in) thick. That's a daunting amount of dung!

The most fantastic find

The most fantastic find In 1991, near Shell in Wyoming, a Swiss team led by Kirby Siber unearthed the best-preserved fossil Allosaurus ever found. It was an almost complete skeleton dubbed 'Big Al'. Big Al had unfortunately died very young with massive injuries. As a consequence, he intrigued the media with his story and featured in the BBC Walking With Dinosaurs special 'The Ballad of Big Al'. Later on, the same team discovered a similar Allosaurus fossil which was even better preserved than Big Al. The fossil was named 'Big Al 2'.

Allosaurus features

Allosaurus features Height: 5m (16.4ft)
Length: 12m (39.36ft)
Weight: 1.4 tonnes (1.57 short tons)
Top speed: 33.8kph (21.00mph)
Vision: Allosaurus had its eyes in front of its head facing forward, so that it would have been better able to work out distance and time to attack.
Skin: The skin of Allosaurus would have been smooth and leathery.
Brain: Allosaurus had an oval-shaped brain, about the size of a small loaf of bread, though probably not as tasty... unless you were another dinosaur.
Prey: Allosaurus was an active predator of large animals such as the long-necked Diplodocus and the plate-backed Stegosaurus. These were all found together at the same time in the same habitat and location.
Bite: The estimated maximum bite force of Allosaurus would be 3,500 newtons, less than alligators and leopards.

Allosaurus facts and theories

Allosaurus facts and theories

  1. Some scientists suspect Allosaurus was a solitary hunter and would have held large territories, much like a tiger, but this is difficult to prove using the fossil record.
  2. Allosaurus had a lifespan of about 25 years. This was about average for a dinosaur of its size, rate of growth and metabolism. By comparison, large dinosaurs such as Brachiosaurus would have lived for over 50 years.
  3. Amazingly, Allosaurus fossils had been preserved for the last 150 million years in the Morrison formation. For palaeontologists, it is a Jurassic playground.
  4. Allosaurus had knife-like teeth that were shed and replaced over its lifetime. The teeth were up to 10.16cm (4in) in length and became shorter, more curved and narrow towards the back of the mouth. These teeth would have been excellent at ripping off pieces of flesh.
  5. Allosaurus could most likely have taken a swim – imagine this gigantic beast coming toward you in the water...
  6. The forearm of Allosaurus was less than 35% the length of its hind limb. Scientists are uncertain why these dinosaurs, as well other bipedal meat eaters, had such short arms.
  7. Overall, dinosaurs were not the brainiest bunch. And though Allosaurus was only as smart as an ostrich, it was a total brainiac compared to dinosaurs like the plate-backed stegosaurs, which had some of the tiniest brains among dinosaurs.