Miacis

Miacis is a small extinct carnivore of the family Miacidae. They were small mammals which lived in forests and climbed trees, and ate small prey. They had the ancestral mammalian number of 44 teeth. In later members the number of teeth began to be reduced. 
"Miacis" had brains that were relatively larger than those of the creodonts. The larger brain size compared to body size suggests their behaviour was becoming more flexible, and possibly more intelligent.
Miacids are either early members of the order Carnivora or in a larger group called the Carnivoramorpha. They may not be monophyletic. One professional opinion is that most "Miacis" species belong to the ancestors of the modern order, the crown-group Carnivora.
The miacids lived 50 to 60 million years ago and were small omnivorous predators. According to one source, it preyed on smaller animals, such as small mammals, reptiles, and birds, and might have also have eaten eggs and fruits.
Some experts think it is a paraphyletic taxon. In other words, they think the name "Miacis" covers a number of different species.