Allosaurus, a formidable bipedal theropod, dominated the Late Jurassic landscapes of North America and parts of Europe approximately 155 to 145 million years ago. Averaging about 8.5 meters (28 feet) in length, this large carnivore was a top predator in its ecosystem.
Prey of the Allosaurus
Allosaurus primarily preyed upon the large herbivorous dinosaurs that shared its Late Jurassic environment. Its diet included ornithopods such as Camptosaurus and Dryosaurus, as well as armored stegosaurids like Stegosaurus. Sauropods, which were massive long-necked dinosaurs, also formed a portion of its diet, including species such as Apatosaurus, Diplodocus, and Camarasaurus.
While capable of taking down medium-sized dinosaurs, Allosaurus likely focused on more vulnerable targets among the larger prey. This often meant pursuing juveniles, or sick and old individuals. There is also speculation that Allosaurus may have engaged in “flesh grazing,” taking bites from very large, still-living sauropods without necessarily killing them.
Scavenging was also a probable feeding strategy for Allosaurus, particularly on the immense carcasses of sauropods. It was an opportunistic feeder, not averse to consuming carrion. During times of environmental stress or food scarcity, Allosaurus may have even resorted to cannibalism.
Hunting Methods and Physical Adaptations
Allosaurus possessed a suite of physical adaptations that enabled its predatory success. Its skull, while large, was relatively light and equipped with dozens of sharp, serrated teeth. These blade-like teeth were designed for slicing through flesh, rather than crushing bone, and were continually shed and replaced throughout the dinosaur’s life.
Its forelimbs, though proportionally smaller than its powerful hind limbs, featured three sharp, curved claws on each hand. These claws were used for grasping and tearing prey, helping to secure struggling victims. The hind limbs were also equipped with strong, raptor-like claws, aiding in holding down prey.
Allosaurus had a relatively weaker bite force compared to later theropods like Tyrannosaurus rex, with estimates around 3,572 Newtons (2,110 PSI). Despite this, its robust skull, strong neck muscles, and ability to open its jaws very wide (up to 90 degrees) allowed for an effective “hatchet-like” attack strategy. This involved slamming its head down to inflict deep, slashing wounds, or using a “strike-and-tear” method to rip off flesh.
The dinosaur was built for speed and agility, with powerful hind legs and a long, muscular tail that provided balance and aided in rapid turns during pursuit. Estimates suggest Allosaurus could reach speeds of 30-55 kilometers per hour (19-34 mph), making it faster than many of its potential prey items. The debate continues regarding whether Allosaurus hunted in coordinated packs or congregated at kills, similar to modern crocodiles or Komodo dragons, where multiple individuals might feed together.
Fossil Evidence of Its Diet
Scientists have pieced together the diet and hunting behaviors of Allosaurus through fossil discoveries. Direct evidence comes from bite marks on the bones of other dinosaurs. For example, Stegosaurus fossils show distinctive wounds matching Allosaurus teeth or tail spikes, indicating predator-prey encounters.
Sauropod bones also exhibit scrapings and bite marks consistent with Allosaurus feeding. Shed Allosaurus teeth alongside sauropod remains further support that Allosaurus either actively hunted these large herbivores or scavenged their carcasses.
Associated remains at fossil sites like the Cleveland-Lloyd Dinosaur Quarry, where numerous Allosaurus skeletons are found alongside potential prey, offer further insights. While these bone beds do not definitively prove coordinated pack hunting, they suggest multiple Allosaurus individuals gathered around abundant food sources, such as carcasses trapped in mud.
Fossilized injuries on Allosaurus specimens also provide clues. Healed wounds, such as those on a tail vertebra likely inflicted by a Stegosaurus spike, indicate dangerous struggles with prey. Bite marks on Allosaurus bones suggest intra-species aggression or cannibalism, particularly in environments with limited resources.