The Allosaurus was a truly terrifying creature. Sharing a similar appearance and appetite with its theropod cousin the Tyrannosaurus, the Allosaurus was likely also an apex predator. Two massive legs supported a body which could weigh up to 1,500 kilograms. The Allosaurus, however, did not possess the skeletal leg makeup of the tyrannosaurids, meaning that its running speeds were limited. There is ample evidence to suggest that the Allosaurus hunted large prey, like the Stegosaurus. Skeletons of both species have been found bearing wounds which could only have been inflicted by the other, including an Allosaurus with thagomizer, or tail spike, wounds in its skull and a Stegosaurus with Allosaurus jaw imprints in its neck plate.
The discovery of the Allosaurus dates back to Ferdinand Hayden in 1869. He received a fossil, which the locals believed to be a petrified horse bone, secondhand from Colorado. Examinations determined that this was no horse bone, but half of a vertebrate from a theropod. At the time the vertebrate was given its own genus, Antrodemus. In 1877, this bone, along with others which were believed to come from the same species, were deemed Allosaurus Fragilis. Allosaurus means different lizard; the vertebrates which had been discovered at the time were very different than all other dinosaur fossils. The second part of its name, Fragilis, was given because the bones had lightening features like cavities within them. The most significant Allosaurus findings occurred between 1960 and 1965 at the Cleveland-Lloyd Dinosaur Quarry in Utah. Remains from an estimated 46 Allosaurs have been recovered there.
There is much debate between experts in the field about whether the Allosaurus was a solitary or pack predator. Skeletons of the creature have typically been found in groups, but this could also mean that numerous unfriendly Allosaurs would feed on the same carcass. Even the largest Allosaurs wouldn’t have had the appetite to devour an entire Stegosaurus in one “sitting”, and leftovers probably weren’t worth risking your life over. Day old Stegosaurs probably didn’t hold up as well as cold pizza.
The Allosaurus didn’t just feed on Stegosaurs though. Stegosaur was a large, well defended animal that wouldn’t have made easy prey. Its large spine plates and spiked tail were daunting defenses. Other, smaller creatures would have been prey to the Allosaurus as well. Studies suggest that juvenile prey was more desirable to the Allosaur than adult prey, likely because they lacked the defense of the adults. Biomechanical analysis of the skeletons has revealed that the Allosaurus could open its jaws to a whopping 79 degrees.
The Allosaurus lived during the late Jurassic Era, and for many years it was believed to be an ancestor of the Tyrannosaurus, but this has been rejected. The Tyrannosaurids belong to a separate family of Carnosauria. Out of the four main families of Carnosauria, the Allosauridae is the smallest.
Popular culture has loved the Allosaurus since its discovery. In Sir Arthur Conan Coyle’s novel The Lost World and its 1925 feature film adaptation (the first film ever to feature dinosaurs) it serves as the apex predator. Along with the Tyrannosaurus, the Allosaurus has come to be recognized as the quintessential large, predatory dinosaur.
The true discovery and classification of the Allosaurus was delayed by a series of events which has become known as the Bone Wars. Also known as the “Great Dinosaur Rush”, the events centered around the fierce rivalry between Edward Cope and Othniel Marsh. The two met in Berlin in 1864 and were fast friends. Between 1872 and 1874 their relationship slowly broke down, and a period of open hostility began. Marsh had access to more financial means than Cope, and was able to hire local fossil excavators while remaining at home to study the fossils he had already found. Cope had to go along with his expeditions. After a series of bribes, thefts, slander, and even the destruction of bones, both men exhausted all of their money. When the dust finally settled in 1892, the two men had discovered a combined 142 new species of dinosaur, although only 32 of these are valid today.
Could more progress have been made if these two great scientists had set aside their egos and worked together? Yes, but then we wouldn’t have something called the Bone Wars.
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