What is "protomammal"

Usage examples of "protomammal".

But at night even humble carnivorous protomammals must have posed a real threat to the cold-immobilized reptiles, and particularly to their eggs.

Happily, that was the stream we belonged to, and it evolved into a family of protomammals known as therapsids.

Just as, if she looked closely, there was a smooth fakeness to the spurting blood of the protomammal, a glistening brightness to the dino's scales.