Dinosaur-Era Mammal Possibly "Mother" of All Humanity

A tiny, dinosaur-era mammal may have been the mother of all humanity -- at least in a sense, National Geographic News reports.

According to a new study, the newly discovered 160-million-year-old fossil species, named the "Jurassic mother from China" [Juramaia sinensis], is the earliest known ancestor of placental mammals -- that is, animals, such as humans, that give birth to relatively mature, live young.

Although it's unclear if the creature is a direct ancestor of modern placentals, it's "either a great grand-aunt or a great grandmother," the study’s authors told National Geographic.

According to the study, the newfound eutherian scurried about temperate Jurassic forests, dined on insects under the cover of darkness, and weighed about half an ounce (15 grams), making it lighter than a chipmunk.

"The great evolutionary lineage that includes us had a very humble beginning, in terms of body mass," Zhe-Xi Luo, a paleontologist at the Carnegie Museum of Natural History in Pittsburgh, who led the team that discovered the fossil, told National Geographic.

The discovery brings the fossil record in line with DNA evidence that indicates that the split between ancestral marsupials and placentals occurred around 160 million years ago, Luo added.

"What is clear is that, besides the fact that marsupials and placentals start to differentiate, we also have the other mammals that diversified as well," he continued. "But we don't know what would be the specific environmental trigger for that."

Placentals, which includes creatures ranging from mice to whales, are all that remain of the eutherian mammals.

The findings of the study will be published Thursday in the journal Nature.

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