Dinosaur National Monument

Dinosaur National Monument

New Dinosaur Species Discovered at Dinosaur National Monument

February 24, 2010, 6:47 am

Scientists, such as Dan Chure, refer to sauropods, the massive, long-necked plant-eating dinosaurs, as "headless wonders."

Not only are their noggins puny in relation to their colossal bodies, but very rarely do paleontologists ever recover complete sauropod skulls, said Chure, of Dinosaur National Monument. But a new species unearthed at the monument several years ago was identified from four skulls - two fully intact - found within a few feet of each other.

Abydosaurus mcintoshi was introduced to the world Tuesday in the German science weekly Naturwissenshaften, where Chure published findings with Brigham Young University collaborators. The new sauropod is believed to be a distant descendant of brachiosaurus, which roamed Utah 150 million years ago.

Finding just one skull would be impressive, but four is beyond what any dinosaur hunter could hope for. The skulls revealed jaws crammed with dozens of tiny teeth.

"It's quite a fortuitous thing. In many dinosaurs, the bones of the head do not fuse up, especially in sauropods. You have an array of components that are held together by soft tissue. The only thing that stays together is the brain case," said Brooks Britt, a BYU geology professor.

National Park Service employees first discovered an interesting cache of bones near the monument's visitor's center in the late 1990s and enlisted Britt's help to prepare the specimens. The monument is famous for dinosaur discoveries made in late-Jurassic-era Morrison Formation. But these new bones were in the younger Cedar Mountain Formation, a 105-million-year-old sandstone that dates the bones to the middle of the Cretaceous, the third and final chapter of dinosaurs' reign that ended 66 million years ago.

After the initial find, park staff delivered a three-ton block to BYU's Museum of Paleontology. Dinosaur bones, including pieces of a skull, were apparent on the surface, but as researchers knocked apart the block, another fully articulated skull emerged. Britt realized he had a rare find.

Of the 120 known species of sauropod at the time, scientists possessed skulls for only seven and most of those were from the Jurassic.

The skulls are on display at the BYU museum, where visitors can watch students prepare other abydosaurus bones.

"The hardest bone I personally have worked on is a vertebra that was half-eroded before discovery and is so fragile that it crumbles if you look at it wrong," said BYU geology major Kimmy Hales.

Britt made follow-up trips to the quarry and found a fourth skull in 2003. All four specimens belonged to juveniles who may have died in the same event and were quickly buried before scavengers and bacteria could destroy the carcasses.

Skull fossils reveal much about an ancient creature's biology and evolution. For Britt and Chure, the abydosaurus' teeth held the most intrigue.

"They are small, small as a triple-A battery cut in half, a centimeter in diameter. Why is that?" Britt said. Perhaps the teeth reflect food sources and eating habits, but the small teeth fit a pattern seen over the course of dinosaur evolution from the Jurassic to the Cretaceous.

"There is a trend from large to small teeth, packing them in there close together, not just in brachiosaurus, but all the sauropods that survived into the Cretaceous," Britt said. "In the Jurassic, they had an array of tooth sizes, but in the end everyone has these small pencil-like teeth. We attribute it to a way to increase the enamel, so their teeth last longer."