ScienceDaily (Feb. 24, 2010) — A team of paleontologists has discovered a new dinosaur species they're calling Abydosaurus, which belongs to the group of gigantic, long-necked, long-tailed, four-legged, plant-eating dinosaurs such as Brachiosaurus.
In a rare twist, they recovered four heads -- two still fully intact -- from a quarry in Dinosaur National Monument in eastern Utah. Complete skulls have been recovered for only eight of more than 120 known varieties of sauropod.
"Their heads are built lighter than mammal skulls because they sit way out at the end of very long necks," said Brooks Britt, a paleontologist at Brigham Young University. "Instead of thick bones fused together, sauropod skulls are made of thin bones bound together by soft tissue. Usually it falls apart quickly after death and disintegrates."
Analysis of the bones indicates that the closest relative of Abydosaurus is Brachiosaurus, which lived 45 million years earlier. The four Abydosaurus specimens were all juveniles.
Most of what scientists know about sauropods is from the neck down, but the skulls from Abydosaurus give a few clues about how the largest land animals to roam the earth ate their food. "They didn't chew their food; they just grabbed it and swallowed it," Britt said. "The skulls are only one two-hundredth of total body volume and don't have an elaborate chewing system."
All sauropods ate plants and continually replaced their teeth throughout their lives. In the Jurassic Period, sauropods exhibited a wide range of tooth shapes. But by the end of the dinosaur age, all sauropods had narrow, pencil-like teeth. Abydosaurus teeth are somewhere in between, reflecting a trend toward smaller teeth and more rapid tooth replacement.
The fossils were excavated from the Cedar Mountain Formation in Dinosaur National Monument near Vernal, Utah. The site is just a quarter of a mile away from the condemned visitor center that displays thousands of bones that remain in place on an uplifted slab of sandstone.