Paleontologists have known for decades that mammals emerged from a broader, diverse group of creatures called synapsids. The very first synapsids of about 306 million years ago were small and ...

Fossil skull of the extinct cynodont therapsid Cynognathus crateronotus. Cynognathus was a powerful predator that was close to being a mammal, but not quite. It has been found in several parts of ...

Amniotes began to radiate in the Carboniferous into many niches previously held by amphibians, plus new niches. The initial split was into synapsids (mammals and their relatives) and sauropsids ...