未分类题

Once found almost entirely in the western United States and ill Asia, dinosaur fossils are now being discovered on all seven continents. A host of new revelations emerged in 1998 that promise to reshape scientists' views of dinosaurs, including what they looked like and when and where they lived.
It is doubtful that Tyrannosaurus Rex had lips or that Triceratops had cheeks, says Lawrence Witmer, an assistant professor of anatomy at Ohio University in Athens, Ohio. Witmer was a leading researcher for a study on dinosaur anatomy that was presented at the annual meeting of the Society for Vertebrate Paleontology, which concluded on October 3 in Snowbird, Utah.
Witmer’s study reached its conclusions by using high-tech computerized axial tomography ( CT or CAT) scans &long with comparative anatomy studies. For example, the theory that Triceratops and similar dinosaur species had cheeks was based on past comparisons with mammals such as sheep. But Witmer’s careful analysis found the structure of the tricera tops jaw and skull made it more likely that Triceratops had a beak like that of an eagle. Witmer said that scientists should use birds and crocodiles as models when researching the appearance of dinosaurs.
In early October scientists announced that they had confirmed the discovery of a new type of ceratopsian dinosaur. The dinosaur's bones, found in New Mexico in 1996, are forcing paleontologists to rethink their theories about when ceratopsians migrated to what is now Noah America.
Scientists previously thought that ceratopsians, the group that included the well-known Triceratops, arrived in North America from Asia between 70 million and 80 million years ago. During this time, the late Cretaceous Period, the cash’s two supercontinents m Laurasia in the north and Gondwanaland in the south -- were in the process of pulling apart, cutting dinosaur populations off from each other and interrupting migratory patterns.
The fossilized bones, found by eight-year-old Christopher Wolfe and his father, paleontologist Doug Wolfe of the Mesa Southwest Museum in Arizona, date to about 90 million years ago. This could mean that ceratopsians originated in Noah America and migrated to Asia rather than the reverse, paleontologists said. Doug Wolfe named the important new species of dinosaur Zuniceratops christopheri after his son.