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BOB HIRSHON (host):
Charting the dinosaurs’ rise to power. I’m Bob Hirshon and this is Science Update.
Did dinosaurs rocket to success, or claw their way to the top? In the past, fossil records have shown little overlap between true dinosaurs and their predecessors, called dinosauromorphs. Scientists suspected that the dinosaurs either made short work of their competition, or filled a void after a mass extinction. But now, at a site in New Mexico, University of California at Berkeley paleontologist Randall Irmis and his colleagues have found fossils of both dinosauromorphs and true dinosaurs.
RANDALL IRMIS (University of California, Berkeley):
They were coexisting for 15 to 20 million years. And this suggests that the rise of dinosaurs was fairly gradual rather than rapid.
Their report also cites earlier finds that have recently been re-evaluated, and now support the idea that dinosaurs took over the world at a more leisurely pace. I’m Bob Hirshon, for AAAS, the science society.