Temporal range: Early Cretaceous
|An artist's illustration of Acrocanthosaurus atokensis|
Stovall & Langston, 1950
| Acrocanthosaurus atokensis|
Stovall & Langston, 1950
Acrocanthosaurus was a very large theropod carcharodontosaurid (carnosaur) dinosaur from North America during the Early Cretaceous Period about 112 million years ago, from the Carcharodontosauridae. It is one of the largest carnivores of said family, and also the fifth largest of North America.
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.
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 11.5 meters (38 feet) and an estimated weight of 5.7 to 6.2 tonnes (6.3 to 6.8 tons), with an upper maximum weight of 7.25 t (7.99 tons) within the realm of possibility. 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 carnivorous theropods would never do.
Acrocanthosaurus is classified in the superfamily Allosauroidea within the infraorder Tetanurae. This superfamily is characterized by paired ridges on the nasal and lacrimal bones on top of the snout and tall neural spines on the neck vertebrae, among other features. It was originally placed in the family Allosauridae with Allosaurus, an arrangement also supported by studies as late as 2000. Most studies have found it to be a member of the related family Carcharodontosauridae.
At the time of its discovery, Acrocanthosaurus and most other large theropods were known from only fragmentary remains, leading to highly variable classifications for this genus. J. Willis Stovall and Wann Langston Jr. first assigned it to the "Antrodemidae", the equivalent of Allosauridae, but it was transferred to the taxonomic wastebasket Megalosauridae by Alfred Sherwood Romer in 1956. To other authors, the long spines on its vertebrae suggested a relationship with Spinosaurus. This interpretation of Acrocanthosaurus as a spinosaurid persisted into the 1980s, and was repeated in the semi-technical dinosaur books of the time.
Tall spined vertebrae from the Early Cretaceous of England were once considered to be very similar to those of Acrocanthosaurus, and in 1988 Gregory S. Paul named them as a second species of the genus, A. altispinax. These bones were originally assigned to Altispinax, an English theropod otherwise known only from teeth, and this assignment led to at least one author proposing that Altispinax itself was a synonym of Acrocanthosaurus. These vertebrae were later assigned to the new genus Becklespinax, separate from both Acrocanthosaurus and Altispinax.
Most cladistic analyses including Acrocanthosaurus have found it to be a carcharodontosaurid, usually in a basal position relative to the African Carcharodontosaurus and Giganotosaurus from South America. It has often been considered the sister taxon to the equally basal Eocarcharia, also from Africa. Neovenator, discovered in England, is often considered an even more basal carcharodontosaurid, or as a basal member of a sister group called Neovenatoridae. This suggests that the family originated in Europe and then dispersed into the southern continents (at the time united as the supercontinent Gondwana). If Acrocanthosaurus was a carcharodontosaurid, then dispersal would also have occurred into North America. All known carcharodontosaurids lived during the early-to-middle Cretaceous Period.
- Acrocanthosaurus appears in the Vivendi Universal video game Jurassic Park: Operation Genesis for PC and console platforms. It can live with Carcharodontosaurus without a fight in the game.
- Acrocanthosaurus also appears in Robert Bakker's novel "Raptor Red" about Utahraptor.
- Acrocanthosaurus appeared in the Dreamworks Interactive video game Warpath: Jurassic Park for the Sony Playstation game console.
- Acrocanthosaurus also appears in Monsters Resurrected: Great American Predator (known as Mega Beast: Dinosaur King in some versions) as top predator and being driven to extinction by climate change and help from Deinonynchus (in real life, Deinonynchus wouldn't be much competition for the larger theropod) and taking down large
- It also appears in the Discovery Channel show Prehistoric as predator to Astrodon and Sauroposeidon (called Paluxysaurus in the documentary).
- It appears in Jurassic Park: Builder as a sliver dinosaur.
- Acrocanthosaurus makes a cameo as a database scene with sauroposiedon in Planet Dinosaur: Episode 5.
- It also made some appearances in Dinosaur King.
- Acrocanthosaurus appears in the game Primal Carnage: Extinction as subclass in the wider tyrant class. It is possible however that like some of the other dinosaurs in the game it is modified (though this is unlikely as it is lighter and smaller than the T. rex as it would be, also the Phoenix documents in the loading screen say the length is 38FT).
- A family of three Acrocanthosaurus appear in The Land Before Time series episode "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.
- It appears in Jurassic World: The Game as a VIP creature.
- Acrocanthosaurus is featured in The Isle as a tier 4 carnivore
- Acrocanthosaurus was gonna make an appearance In the Disney Pixar Film The Good Dinosaur, But was either cut out or deleted.
- In Dinoverse: Raptor Without A Cause and Dinoverse: Please Don't Eat The Teacher, Acrocanthosaurus feature heavily. Patience McCray winds up possessing one she dubs Monica and meets its extended family, a large and loving cooperative pack.
- Acrocanthosaurus also appeared in the ROBLOX game "Era of Terror" before the game was shut down and replaced with "Era of Terror: Remastered".
- Acrocanthosaurus was added to Jurassic World: Evolution on April 17 in the Carnivore Dinosaur Pack. It inaccurately has a very thick head, body and teeth, making it look more like a tyrannosaurid. It also nearly lacks the spine down its back that it was named after, though it is there in the model.
Mosters Resurrected: Great American Predator
The Audubon Society Pocket Guides Familiar Dinosaurs; by Alfred A. Knopf