Allosaurus was one of the largest theropods to have ever existed and inhabited Africa, Europe, and North America about 150 million years ago. The Allosaurus was a genus of the large Carnosaurian dinosaurs, which consists of other theropod dinosaurs.

Allosaurus Key facts

Allosaurus pronunciationThis species is pronounced as “AL-oh-saw-russ”
What does Allosaurus mean?The name is derived from two Greek words “allos”, which means different, and “saurus”, which means lizard.
Dinosaur typeTheropod
On the menuCarnivore
Length12.1 meters (39.7 feet) for females
10.4 meters (34.1 feet) for males
Height3.8 meters (12.5 feet) for females
3.2 meters (10.5 feet) for males
Weight2.3 tons (4,600 lbs)
Life expectancyScientists have concluded that an Allosaurus may have reached full adulthood at 15 years old, and have been expected to live until 28 years old.
Legs usedBipedal
Estimated top speedDue to the Allosaurus’ massive body and two powerful hind legs, researchers show that they can reach up to 33.8 kp/h or 21 mp/h.
When they livedThe Allosaurus lived during the Upper Jurassic Period 150-144 million years ago.
Where they have been found?The fossils of the Allosaurus were found in Utah’s Cleveland-Lloyd Quarry, which contains other dinosaur bones that have been found.

When & Where

The first discovery of the Allosaurus was found in 1869, which was likely to be retrieved from Morisson Formation strata near Granby, CO. In 1877, the fossil was named by Othniel Charles Marsh with the name Allosaurus fragilis, which means a different lizard. The name was given after O.C. Marsh studied the fossil, and discovered that it has features that made the vertebrae lighter.

Size & Weight

Being one of the largest theropods to ever exist, the Allosaurus can weigh about 2.3 tons, which is about 4,600 lbs. Their height also varies depending on being male and female. For females, their height can reach up to 3.8 meters, which is about 12.5 feet. For males, they can reach a height of 3.2 meters, or about 10.5 feet. Their lengths also differ as females can measure up to 12.1 meters or 39.7 feet and males can reach about up to 10.4 meters or 34.1 feet.

Mobility & Diet of the Allosaurus

They had four legs, but their hind legs were much longer than their rear legs, which means that they were bipedal and were known to have used their front legs as a way to attack their prey.

Just like other theropods, they were carnivore, which means that they hunted and ate other dinosaurs. Paleonthologist believe they likely ate large herbivores such as sauropods, ornithopods, and the stegosaurus. Other fossil evidence has shown bite marks on sauropods and stegosaurus that match that of an Allosaurus.

Interesting Points

  • At first it was known as Antrodemus, which means “body cavity” in Greek.
  • The most famous fossil specimen found is named “Big Al”, which can be found at the heart of the University of Wyoming campus.
  • Upon discovery of the fossils, the vertebrae of the Allosaurus fragilis (Latin for “fragile”) were concave on both sides and contained shallow cavities, giving them an hourglass shape, which is different from the other dinosaurs to exists during that time.