Tuesday, January 6, 2009

Mammals only evolved after dinosaurs died out

Tiny mammals lived in the shadow of the dinosaurs for more than 150 million years, occupying ecological niches as small, nocturnal animals weighing as little as 2 grams. The ancestors of mammals, animals called synapsids, actually appeared before dinosaurs.

Mammals remained relatively small until 65 million years ago, when the demise of the dinosaurs left a mass of niches for larger mammals to fill. Most of the types of mammals we know today evolved after this time.

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