Allosaurus was a genus of large predatory theropod dinosaur that lived in the late Jurassic Period around 155–145 million years ago.
Background[]
Real life[]
Allosaurus is one of the most famous and best-studied dinosaurs currently known to science. Its name means "different lizard", alluding to its unique (at the time of its discovery) concave vertebrae. Growing to an average of 8.5 meters (28 feet), 11 meters (36 feet) in the largest specimens and weighing up to two to four tons, it was one of the most formidable and common predators of the late Jurassic Period. Fossils of Allosaurus have been discovered in North America and Portugal, showcasing how widespread it was. Four species of Allosaurus are considered valid; Allosaurus fragilis, Allosaurus jimmadseni, Allosaurus europaeus, and largest of all, Allosaurus anax, which was once thought to be another genus of related dinosaur called Saurophaganax (meaning "king of the lizard-eaters"). Allosaurus had two noticeable crests above and in front of its eyes, which were probably for species recognition and attracting mates.
Like with Tyrannosaurus rex, it was once assumed in the 19th and early 20th centuries that Allosaurus walked in a kangaroo-like posture with a dragging tail, but is now known that the dinosaur walked with its tail straight out behind it and its back level with the ground. Another error made long ago was that it was once thought to be related to Tyrannosaurus, but it is now known that Tyrannosaurus and Allosaurus are from two different families of dinosaurs: Allosaurus is a carnosaur, a member of a group of large predatory dinosaurs that include the larger and later Giganotosaurus and Carcharodontosaurus (and more recently has been shown to include the Megalosaurs and Spinosaurs); while Tyrannosaurus is a coelurosaur, a member of a superfamily of dinosaurs that includes Velociraptor and birds (themselves being highly derived coelurosaurs) as other notable members.
Allosaurus was first discovered in 1869, and described by the famous paleontologist Edward Drinker Cope. Since his initial description, hundreds of specimens of Allosaurus have been found in the late Jurassic fossil beds of the Morrison Formation, which runs from Colorado into Wyoming, Utah, Montana, Kansas, Texas, New Mexico, Arizona, Idaho, North and South Dakota, Oklahoma, and Nebraska. In Europe, Allosaurus has been found in the Lourinha Formation of Portugal. During the late Jurassic, Portugal was a large island close to North America, close enough to have similar animals. One of the best assortments of specimens of Allosaurus anywhere in the world comes from the Cleveland-Lloyd Quarry in Dinosaur National Monument, where the remains of more than 44 Allosaurus have been unearthed. Initially believed to be a predator trap akin to the La Brea tar pits of California, the quarry is now believed by some to have been a watering hole where dinosaurs may have died and were scavenged by hungry Allosaurus, which themselves may have died of disease and harsh conditions after drinking the stagnant, dirty water. This theory is itself supported by the fact that many Allosaurus are juveniles, but cannot yet be completely proven or disproven.
Three of the four species of Allosaurus lived alongside many other famous dinosaurs in the Morrison Formation of North America. There were many herbivores, which consisted of Stegosaurus and its relative Hesperosaurus, the sauropods Brachiosaurus, Diplodocus, Apatosaurus and its close cousin Brontosaurus, Barosaurus, Supersaurus, Amphicoelias, Maraapunisaurus, and Haplocanthosaurus, the ornithopods Dryosaurus, Nanosaurus, Fruitadens and Camptosaurus, and ankylosaurs like Mymoorapelta and Gargoyleosaurus. Carnivores that shared the environment with Allosaurus in America included Ceratosaurus, small coelurosaurs such as Coelurus and Tanycolagreus, the small tyrannosaur Stokesosaurus, Fosterovenator, and the megalosauroids Marshosaurus and Torvosaurus. In Portugal's Lourinha Formation, the fourth species of Allosaurus (A. europaeus) likewise lived alongside Stegosaurus, Ceratosaurus, Torvosaurus, and Supersaurus (once called Dinheirosaurus until it was found they were the same animal). Other, unique dinosaurs from Lourinha included the additional carnivore Lourinhanosaurus, Lusovenator (a small, early carcharodontosaur), Lusotitan (a relative of Brachiosaurus), the camptosaur Draconyx, and the long-necked and heavily spiky stegosaur Miragaia. At the time. Portugal was a massive island close to the North American coastline, allowing for many species to travel and eventually evolve into new species without the dinosaurs shrinking in size from limited resources.
Because of the vast numbers of specimens recovered from Allosaurus, much is known about its life history, behavior, and habits. Allosaurus were apparently similar in lifespan to the later Tyrannosaurus rex, living upwards of 30 years. Juveniles grew quite rapidly, reaching adulthood in about 15 years. In at least one specimen, medullary tissue has been found, suggesting the Allosaurus it belonged to was a female, as medullary tissue is only found in pregnant birds and dinosaurs. Little is known about the nesting habits of Allosaurus, but crushed eggshells from Colorado have been attributed to them. Young Allosaurus were apparently faster than adults and may have hunted smaller, faster prey until they grew to adulthood, when they would focus on larger animals.
The razor-sharp teeth of Allosaurus were best suited for slicing flesh, and biomechanics studies show it was built to take rapid, snapping bites and slice meat rather than crushing bone. Its bite was weaker than a modern lion's, but it could open its jaws more than 90 degrees to take larger bites out of prey. Like sharks, it may have dashed in, taken a bite to wound its victim, and retreated to let its victim weaken from blood loss before attacking again. Similar studies show it also fed like eagles and falcons, using its powerful back and neck to strip meat off bones. Its long arms were also used for wrestling and restraining prey, and the three-fingered hands were tipped with large claws to grip and tear flesh. It is believed to have hunted by ambush, as it was not built for long distance pursuits. Whether or not Allosaurus hunted in groups or cared for its young is still debated.
As a result of its fame and the high interest in understanding its life, Allosaurus has appeared many times in movies, television, and documentaries. In older public media, it has often been confused with Tyrannosaurus, such as Ray Harryhausen's movie The Valley of Gwangi. One of the reasons for this is because in first years after Tyrannosaurus was discovered in the early 20th century, replicas of Allosaurus bones were used to complete the missing areas of the skeleton. More recent media and scientific discoveries have since corrected this.
Appearances[]
The Timekeeper[]
An Allosaurus attacked 9-Eye when she traveled to the Jurassic period.
Toy Story 3[]
Lotso is seen hugging a brown Allosaurus toy, which was among one of the many toys living in Sunnyside Daycare.
Mickey Mouse[]
A Goofy version of an Allosaurus makes a cameo in "Outta Time".
Penn Zero: Part-Time Hero[]
An Allosaurus served as Penn's steed in "The Old Old West" and "Amber".
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