The featured exhibit in the new museum is the Terror of the South exhibit, with a skeleton of a theropod dinosaur known as Acrocanthosaurus atokensis. The name is Greek for "high-spined lizard from Atoka County [Oklahoma] ". (See my article "Biological Nomenclature" for more information about how biologists name organisms.) It was originally named and described in 1950 by Dr. J. Willis Stovall and Dr. Wann Langston Jr., from fragmentary skeletal remains.
You might not have ever heard of Acrocanthosaurus before, it is not a well-known genus of dinosaur. Acrocanthosaurus is known from only four specimens, all found from sediments of the Trinity Group in southern Oklahoma and north central Texas, and a few isolated teeth in Maryland.
Acrocanthosaurus lived about 110 million years ago, during the early Cretaceous Period (140 to 65 million years ago). It stood three meters (9 feet) tall at the hips, was 13 meters (40 feet) in length, and weighed about 2,400 kg (5,280 pounds). From the location of the four known specimens, we know that Acrocanthosaurus lived in Oklahoma and Texas, and it may have ranged across the Southeastern United States as far north as Maryland.
Acrocanthosaurus is in the shadow of the much more famous Tyrannosaurus rex. Let's compare the two dinosaurs. First of all, Acrocanthosaurus lived about 45 million years before Tyrannosaurus rex. Acrocanthosaurus was about the same length as Tyrannosaurus, but not quite as tall, and it was only about half the weight of Tyrannosaurus. Acrocanthosaurus had a narrower, less muscular skull than Tyrannosaurus, and longer, more powerful forelimbs. Tyrannosaurus, with its muscular skull and large teeth, could crush bones, while the thinner, razor-sharp teeth of Acrocanthosaurus were used to tear meat off the bones of its prey.
Acrocanthosaurus gets its name from the tall neural spines on the vertebrae from its neck to the front half of its tail. This was originally interpretted to mean that Acrocanthosaurus had a "sail" on its back, similar to the therapsid reptile Dimetrodon. Jerry Harris at the New Mexico Museum of Natural History and Science, notes that the presence of ligaments and muscles would have given Acrocanthosaurus more of a "hump" on its back, rather than a sail. He speculates that the combination of ligaments and certain features of the vertebrae might indicate that the back of Acrocanthosaurus was designed to be very rigid, anchoring its body against a prey animal trying to shake the predator off.
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