The discovery included two complete skulls from other types of sauropods — an extremely rare find, scientists said.
The fossils offer fresh insight into lives of dinosaurs some 105 million years ago, including the evolution of sauropod teeth, which reveal eating habits and other information, said Dan Chure, a paleontologist at the monument that straddles the Utah-Colorado border.
“You can hardly overstate the significance of these fossils,” he said.
Of the 120 or so known species of sauropods, complete skulls have been found for just eight. That’s mostly because their skulls were made of thin, fragile bones bound by soft tissue that were easily destroyed after death.
“This is absolutely No. 1 in terms of projects I’ve had the opportunity to work on,” said Brooks Britt, a Brigham Young University paleontologist who co-authored a study on the fossils along with University of Michigan researchers.