NORMAN — A new dinosaur called “thunder thighs,” after its enormously powerful leg muscles, has been discovered in Utah.
The discovery of the Brontomerus Mcintoshi is described in a paper published Tuesday in a British journal by an international scientific team that includes Richard L. Cifelli, curator of vertebrate paleontology at the Sam Noble Oklahoma Museum of Natural History.
The fossilized bones of two specimens — an adult and a juvenile — were rescued in the mid-1990s by Sam Noble researchers from a quarry in eastern Utah that had been looted and damaged, possibly by fossil hunters, Cifelli said.
Cifelli and his co-authors classified the new genus based on an incomplete skeleton now held at the Sam Noble museum, including bones from the shoulder, hip, ribs, vertebrae and some unidentifiable fragments.
Brontomerus is a sauropod, a member of the large, plant-eating group of dinosaurs that includes Diplodocus, Aptosaurus and Brachiosaurus, Cifelli said.
The shape of the hip bone indicates the animal would likely have had the largest leg muscles of any dinosaur in the long-necked sauropod family, Cifelli said.
This is reflected in the name Brontomerus, which literally means “thunder thighs.” The dinosaur's species name, Mcintoshi, was chosen in honor of John “Jack” McIntosh, a retired physicist at Wesleyan University, Conn., and lifelong avocational paleontologist.
Brontomerus may have used its powerful thighs as a weapon to kick predators, or to help travel over rough, hilly terrain, Cifelli said.
The Brontomerus lived about 110 million years ago, during the early Cretaceous period, and may have had to contend with fierce raptors, such as Deino
Co-authors with Cifelli of the paper detailing the discovery are Mike Taylor, a researcher in the Department of Earth Sciences at University College London, and Matthew Wedel, assistant professor of anatomy at Western University of Health Sciences, Pomona, Calif.
The paper is published in the British journal Acta Palaeontologica Polonica.
Taylor said the bones discovered by the Sam Noble researchers were used to identify the dinosaur's unique features, primarily the shape of the hip bone.
The wide, blade-shaped bone projects forward ahead of the hip socket, providing a proportionally massive area for the attachment of muscles.
“When we recognized the weird shape of the hip, we wondered what its significance might be, but we concluded that kicking was the most likely,” Taylor said.
Wedel, who first studied the bones as a graduate student at OU, said other marks give additional clues to its lifestyle and environment.
The Brontomerus probably had powerful forelimb muscles and may have been more athletic than other sauropods, he said.
The powerful leg muscles “were perhaps sort of a dinosaur four-wheel drive,” Wedel said.
Brontomerus' unusual hip structure and enormous thigh muscles place it on the list of most extreme dinosaurs, Cifelli said.
Cifelli said the discovery also is significant because it is one of a number of finds over the past 20 years that challenge the previously held idea that sauropods began to disappear in the early Cretaceous period.