Allosaurus

Allosaurus is a genus of large theropod dinosaurs that lived during the Late Jurassic, about 155 to 150 million years ago. Fossils have been found in the Morrison Formation of western North America, making it one of the best-known predatory dinosaurs of its time. It shared its environment with sauropods, armored dinosaurs, and other theropods, and its fossils have contributed to understanding Jurassic predator communities.

Allosaurus was a bipedal carnivore with a massive skull, long jaws, and sharp serrated teeth. Estimates commonly place mature individuals at about 8 to 12 meters in length and around 1 to 3 metric tons in weight. The forelimbs were relatively short with three clawed fingers, while the hind limbs were long and powerful. The tail was long and helped balance the body during movement. The skull features multiple openings, or fenestrae, and a robust jaw capable of delivering strong bites.

Allosaurus fragilis, described by Marsh in 1877, is the type species of the genus. The name Allosaurus means “different” or “other lizard.” Numerous additional fossils have been attributed to various species, making Allosaurus one of the best represented theropod groups from the Morrison Formation.

Ecology and behavior: Allosaurus likely played the role of top predator in its ecosystem. It probably preyed on large herbivores such as sauropods and ornithopods, and may have scavenged as well. Its limb proportions and muscle attachment suggest it was capable of rapid bursts to capture prey, though precise hunting strategies remain debated among paleontologists.

Fossil record: Dozens of skeletons and skulls have been found, including nearly complete specimens. These finds provide important data on theropod anatomy, growth, and evolution and help illuminate the dynamics of Jurassic predation in North America.