10 Discoveries That Change How You Picture The Ancient Earth
10Mammals’ Ancestors Ruled The Earth Before The Dinosaurs Mammals and reptiles don’t look alike, but they do share a common ancestor. As they went their separate ways, reptiles such as the ancestors of dinosaurs became diapsids. The forefathers of today’s mammals became synapsids. That rivalry lasted for over 230 million years, and mammal-synapsids totally dominated dino-diapsids for the first half of that time. Dimetrodon, for instance, a sail-backed mammal ancestor, was the dominant land carnivore of the Permian period....