"Fran" the Acrocanthosaurus atokensis

CRETACEOUS KILLER COMES OUT OF THE CLOSET

after 120 million years

Friday, August 30, 1996

Hill City, South Dakota-- Today, Geological Enterprises of Ardmore, Oklahoma and Black Hills Institute of Geological Research, Inc. of Hill City, South Dakota announce the unveiling of a new dinosaur skeleton at 2:00 p.m. on Sunday, 8 September 1996 at the Black Hills Museum of Natural History in its temporary home at 217 Main Street in Hill City.

After more than a decade of excavation and preparation, not to mention 120 million yearsof lying entombed in an ancient stream bed, the nearly forty foot long skeleton of this predatory dinosaur, Acrocanthosaurus atokensis is standing tall. "Even those of us involved in the preparation of this skeleton are awed by the sense of power we feel in the presence of the mounted skeleton." explained Terry Wentz while showing the dinosaur to a visitor. This enormous carnivore was closely related to Carcharodontosaurus saharicus from Africa (new remains of this dinosaur were recently unearthed by Dr. Paul Sereno of the University of Chicago) and was nearly as large as Tyrannosaurus rex but lived more than 50 million years earlier.

This skeleton of Acrocanthosaurus was excavated over a period of three years, beginning in 1983, from private land in McCurtain County in southeastern Oklahoma by amateur collectors, Cephis Hall and Sid Love. The specimen was eventually purchased by Allen and Fran Graffham of Geological Enterprises in Ardmore, Oklahoma. Transported to Black Hills Institute in Hill City, South Dakota, a team of expert fossil preparators invested thousands of hours in the painstaking process of cleaning the bones, restoring the skeleton and mounting a museum quality cast replica. A cast replica was mounted rather than risk damaging any of the original skeleton. Mr. and Mrs. Graffham also financed the preparation and restoration of this magnificent skeleton and will be present for the unveiling. Bob Farrar of Black Hills Institute told the press that "Without the Graffham's willingness to invest in the purchase and preparation of this specimen, scientists would still know very little about this intriguing but poorly understood dinosaur genus."

The name Acrocanthosaurus atokensis was first assigned to two very incomplete skeletons excavated from Atoka County in Oklahoma which were described in 1950. Many trackways have been found with what have been described as the footprints of this, apparently abundant, but extremely elusive killer dinosaur. One well known trackway discovered near Glen Rose Texas shows what appears to be an attack upon a much larger sauropod (long necked) dinosaur by an Acrocanthosaurus.

Surprisingly, however, until the discovery and study of this specimen, very little was known about this genus and species of dinosaur. In fact, the remains which had previously been found were so incomplete that scientists could not determine the lineage of Acrocanthosaurus, i.e. who were its relatives? Now, with this specimen prepared, a great deal more about Acrocanthosaurus and its family history has been discovered. As a result of the completeness of this specimen and its collection and preparation, scientists have been able to determine the close relationship of Acrocanthosaurus to Allosaurus, a Jurassic dinosaur from North America. and unite the mid Cretaceous, African dinosaur, Carcharodontosaurus saharicus, to the Allosaurs, as well.

The skeleton is marvelously preserved, the bones turned nearly jet black by minerals migrating via ground water through the sediment. The skull is so well preserved that it is one of the most complete dinosaur skulls ever excavated. This specimen also has nearly complete arms and shoulder girdles. The arms and shoulders of this Acrocanthosaurus are much larger and more heavily muscled and thus probably more powerful than the arms of Tyrannosaurus rex. Each arm terminates in three wickedly curved large claws, well designed for capturing and holding prey.

There is evidence in the skeleton of what was probably a near fatal 'hunting accident' in a punctured shoulder blade and several broken ribs that have healed. "Obviously, even this powerful predator had enemies capable of causing it serious damage," said Neal Larson when the injuries were uncovered during preparation.

One of the most bizarre and prominent identifying features of the Acrocanthosaurus species is the presence of extremely long spines along the top of the vertebrae of the back, hips and tail. These long spines give this dinosaur a surreal appearance even as a skeleton. They must have imparted a fiercely menacing, almost armored look, to the living predator. These spines also gave this dinosaur its name as Acrocanthosaurus, literally translated, means "high spined lizard". Allen Graffham says; "Everyone who sees this magnificent skeleton will understand how and why it got its name".

Allen and Fran Graffham

The beautiful skull of "Fran" the Acrocanthosaur

Casts of "Fran" are Available from the WMNH giftshop!