Washington, DC - Dinosaur fossils are providing the answers to some of scientists' biggest questions about evolution, according to paleontologist Paul Sereno, who has assembled the most up-to-date picture yet of dinosaur evolution in the 25 June 1999 issue of Science.
In his article, which is part of Science's special issue about evolution, Sereno shows how dinosaur fossils hold the clues to questions such as: How does an upstart group of species beat out the dominant group? How do organisms develop nifty new tricks like flying? And how does the breakup of a supercontinent affect the course of evolution?
These major events in the history of life, involving global patterns and trends that occur over millions of years, are crucial aspects of evolution not accessible from the anatomy and genes of living animals. "Certain questions about evolution can only be investigated at the grandest scales using the fossil record," said Sereno, who is from the University of Chicago.
The radiation of new dinosaur species was a spectacular and long-lasting success. In fact, during the Mesozoic era (248 to 65 million years ago), all the land animals more than one meter long were dinosaurs. The only other group of animals to dominate their ecosystem so thoroughly were the mammals of the following era, the Cenozoic (65 million years ago to the present).
Paleontologists have argued about the secret of the dinosaurs' success for
years. Does one group of animals make it to the top by gradually pushing other,
less well-adapted animals out of the picture? Or does the group take a more
opportunistic approach, moving in after a mass extinction event has wiped out
its competition? Recent dinosaur fossil finds suggest the latter, Sereno and
other scientists conclude. For example, the dinosaurs' heyday didn't begin until
at least 15 million years after the first dinosaurs appeared on Earth,
but it did coincide with a mass extinction that killed off many
Contact: Heather Singmaster
American Association for the Advancement of Science