Sources: Eurekalert, PNAS
quote: Dinosaurs went extinct because their migratory paths were cut by the expanding oceans at that time. (All oceans are less than 200 million years old.) Mammals continually raided the dinosaur nests to the point where they could no longer keep up their numbers. Mammals just became too adept at making a living off dinosaur eggs, their numbers grew too great, and there simply was no way for dinosaurs to counter them. Except for the dinosaurs that could lay their eggs in high places unreachable by the mammals.... these became the birds.