Dinosaur Facts: Allosaurus

During the late Jurassic period, the Allosaurus was the largest meat-eating dinosaur. This terrifying predator was dubbed the ‘Different Lizard’ because it possessed a vertebrae that was different that the other dinosaurs of its time. In this article, you will learn other distinguishing characteristics of the Allosaurus, including its diet, body parts, and common behavior.

The Body

The Allosaurus had a body that grew up to 38 feet long and 16 ½ feet tall, and could weight around 1400 kilograms. Depending on the species of Allosaurus, the weight varied. For example, the Allosaurus fragilis could reach a weight between 1.1 and 1.9 tons, while the A. amplexus reached heavier weights up to 5 tons. It’s skull alone was 3 feet long decorated with two short brow-horns and bony knobs and ridges positioned above the eyes and on the top of his head. Long, sharp teeth with serrated edges measured 2 to 4 inches long within the powerful jaws of the dinosaur.

Walking through the jungles of prehistory, the Allosaurus powered its body with two strong legs. Attached to his bulky body filled with heavy bones, a massive tail trailed behind the dinosaur. The Allosaurus had short arms with hands that displayed three fingers with sharp claws that measured up to 6 inches long.

The Allosaurus was equipped with thin, fragile ribs in the middle of its body called gastralia that served as support and protection for the internal organs of the dinosaur. The creature did not have ribs that were attached to a backbone. Instead, they were connected to the skin in the stomach region.


With its sharp, pointed teeth and strong jaws, the Allosaurus was the largest of its kind within the habitat. It is thought that the Allosaurus preyed on plant-eating dinosaurs, such as the Stegosaurus. The dinosaur was fierce and had the power to kill medium-sized sauropods, like the Apatosaurus. Evidence of this type of kill showed Allosaurus tooth marks on the vertebra of an Apatosaurus. Some researchers also believe the Allosaurus was a scavenger.


Scientists believe the Allosaurus may have hunted in groups, which gave them the advantage of ambushing huge sauropods , like the Diplodocus and Camarasaurus. During the late Jurassic period, the Allosaurus was the most abundant predator in North America. The Allosaurus ranked high in intelligence when comparing its brain to its body weight.
Allosaurus Fossils and Discoveries

The largest meat-eater during the late Jurassic period lived around 154 to 144 million years ago. It was given its name in 1877 from a paleaontologist named Orthniel C. March. In 1877, the first nearly complete skeleton of the dinosaur was found by a rancher named M P Felch , in Colorado. To date, more than 60 Allosaurus fossils have been discovered. Most have been located in the Morrisson Formation in Colorado. Around the world, there is evidence to indicate that the Allosaurus also lived in Portugal, Africa, Australia, and western North America.

Classification of the Allosaurus

When classifying the Allosaurus, it had a hollow nerve chord ending in a brain (Phylum Chordata), lizard-hipped dinosaurs (Order Saurischia), diapsids with socket-set teeth (Class Archosauria), bibedal carnivores (Suborder Theropods), and was a large predator with bony head ridges (Family Allosauridae).