eomaia
The earliest placental mammals may have evolved about 110 million years ago. The ancestor of placental mammals may be the extinct genus Eomaia . Fossils of Eomaia have been found in what is now China. It was only about 10 centimeters 4 inches long. It was a tree climber and probably ate insects and worms. Eomaia had several traits of placental mammals. Figure below shows how Eomaia may have looked.