Trilobite finds are common in Oklahoma.
Five major fossil discoveries were made in Oklahoma between the 1930s and 2010. Most counties of Oklahoma, especially the eastern and southern parts of the state, have fossils of some type that range in age from 85 million to about 500 million years old.
Saurophaganax Maximus, a carnivorous dinosaur from the Jurassic Period, became Oklahoma’s official fossil in 2000 as an honor to the state’s paleontological history. Saurophaganax Maximus is the only dinosaur known to have been on the terrain that became the state. This theropod was 5 meters high with a length of 12 meters. It would have hunted on plains as well as lowlands.
Aciculopoda Mapesi is the oldest known shrimp at 370 million years old as well as the oldest decapod found in the United States. Its discovery by Ohio University paleontologist Royal Mapes and his students was confirmed to the public in 2010. The previous oldest shrimp was a 245 million year old version found in Madagascar. Preservation of muscle tissue from the tail gave scientists the chance to run tests they could not do with many fossil finds.
Trilobites are representative of at least half of the Cambrian period fossils in the United States. Their flat, oval bodies show a relation to present chelicerates such as horseshoe crabs. Many areas of Oklahoma list trilobite discoveries because the land was under shallow sea in the Paleozoic Era. The fossils range in age from 250 million to 540 million years old.
The Cretaceous Period between 65 million and 144 million years ago saw many sea creatures such as cephalopods inhabit the area that would be Oklahoma. Clam and snail fossils are constantly discovered across the state.
Paleontologists J. Willis Stovall and Wann Langston, Jr. found Acrocanthosaurus Atokensis in Atoka County during the 1950s. They chose the name to highlight the sizeable spines that go across certain areas of the dinosaur’s body. The fossils indicate the 18-foot tall meat-eater was between 146 and 100 million years old.
The Morrison Formation of Cimarron County is a prominent site for fossil discoveries from the Jurassic period. Richard Cifelli and a team from the Oklahoma Museum of Natural History are credited with the discovery of the Sauroposeidon in 1994. At 56 feet, the dinosaur is the tallest known specimen from southwestern Oklahoma.