Dino Birth Pushed Back 9M Years

Researchers analyzing footprints in 250 million-year-old Polish rock say they've identified the oldest dinosaur-like species ever discovered. Prorodatcylus walked on four legs, was about the size of a house cat, and lived in the shadow of its "more diverse, successful, and abundant crocodile-like cousins" for millions of years, according to the researchers. The discovery means that dinosaurs emerged some 9 million years earlier than had previously been believed, say the scientists.

The footprints prove that dinosaurs arose just 2 million years after the Permian extinction wiped out over 90% of life on Earth, the researchers say, indicating that the rise of the dinosaurs is directly related to the extinction. "Without this mass extinction there would never have been dinosaurs," the lead researcher tells the BBC. "There's a degree of symmetry about that because when dinosaurs went extinct 65 million years ago, that opened space for mammals." (More dinosaurs stories.)