Profile view of Allosaurus fragilis
Kingdom Animalia
Phylum Chordata
Superclass Tetrapoda
Class Reptilia
Subclass Diapsida
Superorder Dinosauria
Order Saurischia
Suborder Theropoda
Superfamily Allosauroidea
Family Allosauridae
Subfamily Allosaurinae
Genus Allosaurus
1st Species Allosaurus fragilis
2nd Species Allosaurus europaeus
3rd Species Allosaurus jimmadseni
Other attributes
Time Range 155-150 mya
Location United States of America, Portugal
Name Meaning Different reptile
Physical Dimensions 9.1 meters long for A. fragilis; 8 meters long for A.europaeus; 7.6 meters long for A.jimmadseni
Weight 2.7 tonnes for A.fragilis; 1.7 tonnes for A.europaeus; 1.6 tonnes for A.jimmadseni
Dietary Classification Carnivore
Allosaurus is an allosaurid theropod dinosaur from the Late Jurassic of the United States of America and Portugal. It was named in 1877 by Othniel Charles Marsh. It was the most common large Jurassic carnivore in the Western United States; as well as this, it is a prominent Mesozoic apex predator in pop culture, only being overshadowed by Tyrannosaurus.


Allosaurus was a bipedal dinosaur with a semi-bulky body, moderately long legs, a long tail, a moderately long neck, and a large head with a mouth containing lots of big teeth. Perhaps the most defining trait of Allosaurus was the pair of large, backwards-facing, horn-like crests atop its head; as well as this, its arms were longer than those of other large theropods (bipedal, mostly carnivorous dinosaurs), and bore 3 fingers on each hand. Its body would have been covered in scaly skin.


Allosaurus was a predator, preying on ornithopods, mid-sized sauropods, stegosaurians, small crocodylomorphs, small pterosaurs, and smaller theropods. Its teeth had knife-like serrations from back to back, and were used to slice off pieces of flesh from the bodies of large prey.


Like the later Tyrannosaurus, Allosaurus was an efficient hunter, equipped with good olfactory (smelling) senses, a tremendously wide gape, and razor-sharp teeth; once it spotted a large herbivore, it would charge at it, bite a large chunk of flesh off its body with its jaws, and let it attempt to run away, as the great amount of blood loss would soon weaken it and allow the theropod to go in for the kill. For a while, it has been suspected that Allosaurus had a bite weaker than that of a lion, and some people have said that it had to use its head like an axe in order to kill prey; however, this has been disproved, as people have discovered that such attack strategies would break all of its teeth (proving very costly for even a dinosaur with teeth that continually replaced themselves), and that a simple, muscle-powered bite that ripped through flesh would have sufficed instead. As well as this, a later study proved that its bite performance was similar to that of dinosaurs such as Carnotaurus and Majungasaurus, proving more than capable of biting through smaller animals. Due to a massive bonebed containing multiple Allosaurus individuals, we can assume that the theropods hunted in packs in order to take down herbivores such as Stegosaurus, Diplodocus, and Brontosaurus; however, while pack-hunting is suitable for almost any carnivorous theropod, these bonebeds actually show that the dinosaurs descended into a feeding frenzy and cannibalized their younger brethren, very similarly to modern reptiles such as crocodiles and Komodo dragons.

In popular cultureEdit

Allosaurus was first introduced to the public in the 1912 novel, The Lost World, where it appears as the main antagonist and tries to eat the exploration team. Since then, it has managed to become an extremely popular theropod dinosaur, appearing in every adaptation of the novel, as well as other major pieces of media such as Land of the Lost, One Million Years B.C, The Valley of Gwangi, Walking with Dinosaurs, Planet Dinosaur, and Jurassic World: Fallen Kingdom; an interesting thing to note is it has a reputation and "personality" similar to that of Tyrannosaurus, depicted as a murderous, persistent brute in fantasy films, and portrayed as more passive and animalistic in documentaries. Its latest public appearance was in the 2019 science fiction short film, Battle at Big Rock, where it attempts to prey on a family of Nasutoceratops right before breaking into the nearby RV to attack everyone inside due to hearing a baby crying loudly.

Community content is available under CC-BY-SA unless otherwise noted.