Thrinaxodon.

Thrinaxodon was a cynodont synapsid. It lived in the early triassic. Being cat sized it didn't have alot of defences against predators but there is a hypothesis that states that it was a social animal so it might have behaved like a prairy dog with one indivisual looking out for dangers and calling to the rest of the group to run or mobbed it's predators protecting there young. Being a generalist it would eat anything from carrion to frogs and lizards. It may have had a cold wet nose,wiskers, and fur. It would probably look like a weasel or ferret.