Earliest Known Ancestor of Placental Mammal Discovered

Researchers today announced the discovery of the earliest known ancestor of the group of mammals that give birth to live young. The finding is based on a well-preserved fossil of a tiny, hairy 125-million-year-old shrewlike species that scurried about in bushes and the low branches of trees.

“We found the earliest ancestor, perhaps a great uncle or aunt, or perhaps a great grandparent–albeit 125 million years removed–to all placental mammals,” said Zhe-Xi Luo, a paleontologist at the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania. “It is significant because a vast majority of mammals alive today are placentals.”