One of the best-known of the giant flesh-eating dinosaurs of the Jurassic Period was Allosaurus. This animal resembled Tyrannosaurus, the monster dinosaur that would appear 70 million years later. Since fossil footprints of several Allosaurus have been found together, some scientists believe these animals may have hunted in packs to bring down much bigger game. Others think that large allosaurs may have killed and eaten smaller individuals that tried to muscle in on their dinner.
■ When: 150 million years ago (Late Jurassic)
■ Fossil location: USA, Portugal
■ Habitat: Plains
■ Length: 39 ft (12 m)
■ Diet: Meat
When young, Allosaurus was a fast runner and probably actively chased after prey, sprinting on its long and powerful hindlimbs. Older individuals were heavier and probably relied more on ambushing victims than running them down. The long, curved claws on the hands were used like meat hooks to capture prey. As well as hunting, Allosaurus may have also scavenged on dead animals.
The massive skull had large openings that made it lightweight, yet strong. The bone was also riddled with smaller holes that may have contained air sacs linked to the lungs.
Although Allosaurus was a fierce predator, scientists think it had a rather weak jaw that prevented it from crunching bones. Its teeth were like saw blades and could slice through skin and muscle to tear out great ribbons of flesh. Victims that managed to escape after being attacked would probably have bled to death.