Dinos Coexisted With Precursors

Fossils newly discovered in New Mexico are challenging the theory that early dinosaurs quickly drove their reptilian predecessors into extinction. The bones, 215 million years old, indicate that these pre-dinosaurs lived alongside their more evolved relatives—which were merely the size of dogs—for up to 20 million years longer than scientists initially believed.

At least two new species of the primitive dinosaurs, known as basal dinosauromorphs, were unearthed at a site where scores of early dinosaurs have already been excavated. The true dinosaurs the "wannabes" coexisted with were hardly the dominating predators they later became in the Jurassic era. "It wasn't instant competitive superiority," said one paleontologist. (More fossil stories.)