Acrocanthosaurus

Dinosaur Discovery Chronicles: The first Acrocanthosaurus bones were found in southeastern Oklahoma and unearthed by Cephis Hall and Sid Love. They sold it to Grafham Enterprises of Ardmore, Okla. There is one named species (A. atokensis), which is named after Atoka County in Oklahoma, where the original specimens were found. The name was coined in 1950 by American paleontologists J. Willis Stovall and Wann Langston, Jr. Langston had proposed the name "Acracanthus atokaensis" for the genus and species in his unpublished 1947 master's thesis, but the name was changed to Acrocanthosaurus atokensis for formal publication.



Mounted Acrocanthosaurus skeleton (NCSM 14345) at the North Carolina Museum of Natural Sciences.
Acrocanthosaurus(ACK-roh-KAN-thuh-SAW-rus), meaning 'high-spined lizard') is a genus of theropod dinosaur that existed in what is now North America during the Aptian and early Albian stages of the Early Cretaceous. Like most dinosaur genera, Acrocanthosaurus contains only a single species, A. atokensis. Its fossil remains are found mainly in the U.S. states of Oklahoma and Texas, although teeth attributed to Acrocanthosaurus have been found as far east as Maryland.

Acrocanthosaurus was a bipedal predator. As the name suggests, it is best known for the high neural spines on many of its vertebrae, which most likely supported a ridge of muscle over the animal's neck, back and hips. Acrocanthosaurus was one of the largest theropods, approaching 12 meters (40 ft) in length, and weighing up to 6–7 metric tons (6.5–7.5 short tons). Large theropod footprints discovered in Texas may have been made by Acrocanthosaurus, although there is no direct association with skeletal remains.

Recent discoveries have elucidated many details of its anatomy, allowing for specialized studies focusing on its brain structure and forelimb function. Acrocanthosaurus was the largest theropod in its ecosystem and likely an apex predator which possibly preyed on large sauropods and ornithopods.

Discovery and naming
Acrocanthosaurus is named for its tall neural spines, from the Greek akra ('high'), akantha ('thorn' or 'spine') and sauros ('lizard').

There is one named species (A. atokensis), which is named after Atoka County in Oklahoma, where the original specimens were found. The name was coined in 1950 by American paleontologists J. Willis Stovall and Wann Langston, Jr. Langston had proposed the name "Acracanthus atokaensis" for the genus and species in his unpublished 1947 master's thesis, but the name was changed to Acrocanthosaurus atokensis for formal publication.

The holotype and paratype (OMNH 10146 and OMNH 10147), described at the same time in 1950, consist of two partial skeletons and a piece of skull material from the Antlers Formation in Oklahoma.

Two much more complete specimens were described in the 1990s. The first (SMU 74646) is a partial skeleton, missing most of the skull, recovered from the Twin Mountains Formation of Texas and currently part of the Fort Worth Museum of Science and History collection.

An even more complete skeleton (NCSM 14345, nicknamed 'Fran') was recovered from the Antlers Formation of Oklahoma by private collectors, prepared by the Black Hills Institute in South Dakota, and is now housed at the North Carolina Museum of Natural Sciences in Raleigh. This specimen is the largest and includes the only known complete skull and forelimb.

Skeletal elements of OMNH 10147 are almost the same size as comparable bones in NCSM 14345, indicating an animal of roughly the same size, while the holotype and SMU 74646 are significantly smaller.

Acrocanthosaurus may be known from less complete remains outside of Oklahoma and Texas. A tooth from southern Arizona has been referred to the genus, and matching tooth marks have been found in sauropod bones from the same area. Several teeth from the Arundel Formation of Maryland have been described as almost identical to those of Acrocanthosaurus and may represent an eastern representative of the genus. Many other teeth and bones from various geologic formations throughout the western United States have also been referred to Acrocanthosaurus, but most of these have been misidentified.


More info
It’s very, very rare. Only four skeletal specimens have been found and most of the remainder are fragments or teeth. The Museum’s Acrocanthosaurus specimen is the best yet unearthed, with 54 percent of the bones represented, and the only one with a complete skull.Before this specimen was discovered, paleontologists couldn’t even determine the dinosaur’s general appearance. One other museum has a cast of Acro, but the N.C. Museum of Natural Sciences is the only place in the world to see the actual fossil.