Acrocanthosaurus

***Acrocanthosaurus*** was a very large theropod allosaurid (carnosaur) dinosaur from North America during the Early Cretaceous Period about 112 million years ago, from the Acrocanthosauridae.

## Discovery Edit

In 1950, a team of scientists, led by paleontologists J. Willis Stovall and Wann Langston, Jr, was excavating in the deserts of Oklahoma when they came across very large fossilized bones and tall vertebrae. They were taken to a nearby museum and were found to belong to a new species of very large theropod dinosaur. It wasn't long afterward that it was officially named *Acrocanthosaurus atokensis*, or "Atoka's high-spined lizard", after the tall spines along its back and the area in Oklahoma where it was first found. However, it was first discovered in 1940s but hadn't gained any attention until its rediscovery a decade later. Since then, several more *Acrocanthosaurus* specimens have been found, and even a very well preserved fossil trackway of it chasing down a *Sauroposeidon*. It's been found in several states along the western half of America, including Oklahoma, Texas, Wyoming, Arizona, and even as far east as Maryland some specimens have been found, suggesting *Acrocanthosaurus* was a very successful predator. And in 2012, the pubic bones, vertebrae, and fibula of a juvenile Acrocanthosaurus were found in the Cloverly Formation in Wyoming, suggesting this theropod was the only large predator in this formation during the time of the dinosaurs.

## Description Edit

*Acrocanthosaurus* was a large carnosaur theropod dinosaur that had a large head, many sharp teeth, strong arms, powerful back legs, and a long slender tail that balanced its body when it ran. It lived alongside the small raptor *Deinonychus*, some small ankylosaurs, and hunted large sauropods. *Acrocanthosaurus* had one feature that made it look very different from other theropods; the tall "sail" along its neck, back, and tail. The sail was formed by very tall spines on the bones of the spine (vertebrae). Some of these spines were over a foot tall. It may represent an evolutionary link between the Late Jurassic *Allosaurus* and the gigantic Early Cretaceous *Carcharodontosaurus*. It was one of the largest bipedal carnivorous dinosaurs, with one mounted specimen reaching a length of possibly 12.5 meters (41 feet) and an estimated weight of 4 to 6 tons. Many of its vertebrae had high neural spines, though nowhere as high as those of *Spinosaurus*.

Scientists have debated why *Acrocanthosaurus* had a sail or a ridge along its back. Some think it released heat when the animal was too hot. It also may have been used for display to make the animal look bigger when it faced rivals for territories or mates. This is much like a house cat fluffing up its fur and arching its back to make itself look bigger. There are other large tall-spined dinosaurs from Europe and Africa, but scientists don't know how *Acrocanthosaurus*is related to them. *Altispinax* had spines almost three-feet tall and *Spinosaurus* had six foot tall spines on its back. Paleontologists have built the dinosaur from parts of three skeletons. One skeleton had a three-foot-long skull. An adult *Acrocanthosaurus* was about ten feet tall at the hips and weighed between three to five tons.

Scientists have found footprints probably made by *Acrocanthosaurus* in several places in Texas. In one place, it looks like an *Acrocanthosaurus* stalked a large sauropod across a mud flat, possibly *Sauroposeidon*. When the sauropod footprints changed direction, so did those of *Acrocanthosaurus*. The outcome of this discovery shows that the *Acrocanthosaurus'* jaws were hanging onto one of the thighs of the sauropod while the it was running. The predator would then rip out a chunk of flesh and the sauropod later died of loss of blood and infection. This discovery concluded that *Acrocanthosaurus* was known for hunting large sauropods, something that most carnivores would never do.

## The Land Before Time Edit

A family of three Acrocanthosaurus appear in The Lonely Journey. After hiding from Red Claw, Chomper came across a young Acrocanthosaurus. He tried to teach it to play catch but it didn't understand him (probably because he was talking in leafeater). It brought it's parents who chased Chomper, but Chomper escaped by hiding behind a rock, where the adults could not find him.