The limbs sat directly under the body, like modern mammals, but unlike other known synapsids.

Did it wipe out the dinosaurs and prepare the earth for the evolution of the modern mammals and man?

All are small compared to modern mammals, the largest being sheep-sized.

The group includes modern mammals as well as their extinct ancestors and close relatives.

This environment endured from 50 million to about 35 million years ago - a critical time in the development of modern mammals.

During its 22 million years, modern mammals became prominent.

It has been suggested that this group contained the ancestors of modern therian mammals.

Being a cynodont, it was a relative of the direct ancestor to modern mammals.

It may have been an ancestor of all modern mammals.

On the other hand, they differ from modern mammals: