"High-spined lizard (from) Atoka"

Acrocanthosaurus atokensis —or Acro—was a bipedal carnivore that lived 100 to 115 million years ago. Acro’s most distinctive feature was a tall “sail” along its neck, back, and tail. Scientists are unsure what purpose it served. One possibility is that Acro used the sail to regulate its body temperature. The sail may have also served as a defensive measure. For example, Acro could have used the sail to appear larger when facing rival dinosaurs. 

Acro was one of the largest predators to ever walk the earth (38 ft. long). It preferred to stalk its prey in open, arid environments or low-lying riverbeds. The bulk of its diet was probably made up of small, plant-eating dinosaurs like Tenontosaurus (26 ft. long). Footprints in the Glen Rose trackway suggest that Acro may have even hunted larger dinosaurs like Sauroposeidon (112 ft. long). However, a few scientists dispute that theory. After all, a full grown Acrocanthosaurus was only as big as Sauroposeidon’s neck! 

McCurtain County “bones”

Acrocanthosaurus was discovered by J. Willis Stovall and Wann Langston, Jr. near Atoka, Oklahoma in 1940. Scientists have found other fossils in in Texas, Utah, and even Maryland. However, the most complete skeleton was unearthed by two amateur paleontologists, Cephis Hall and Sid Love, less than twenty miles away from the Museum in 1983. The two men managed to recover fifty percent of the skeleton—including the entire skull.

Unfortunately, the fossil was extremely fragile. The organic matter in prehistoric remains is usually replaced by stable quartz compounds. However, this fossil was made up of unstable marcasite and pyrite. The former crumbles in open air when in a non-crystalline state. The latter can emit sulfuric acid fumes when removed. The two men needed more help.

The men contacted Allen and Fran Graffham of Geological Enterprises in Ardmore, OK. With their help, the remains were moved to the Black Hills Institute for Geological Research in South Dakota. A dedicated lab space was built to handle the hazardous and brittle remains; the fossil was saved a few years later. It was sold to the North Carolina Museum of Natural History, where it rests today.

The cast at the Museum of the Red River is a faithful copy of the original bones, with scientifically-determined replacements for the rest. Its acquisition was made possible by a group of third and fourth graders, who led a two-year, county-wide effort to obtain the cast.

Please note, due to ongoing construction, Acro is off display.