Anatomy: Morganucodon was a tiny, rat-like quadruped that had 5-toed feet and a short tail. It was about 4 inches (10 cm) long; it had short legs, a long, narrow snout, and both sharp teeth plus grinding molars. This early mammal belonged to the Order Triconodont (having 3 cups on molars).

Its large eyes probably indicate that it was nocturnal. Morganucodon was probably warm-blooded, but may have laid eggs, like other primitive mammals.

Diet: Morganucodon ate insects and other small animals.