A recent fossil find is more evidence that the well-known “Lucy” species was not alone in the region now known as Ethiopia, a new study suggests.

A lower jaw, along with jaw fragments and teeth, dated at between 3.3 million to 3.5 million years old, were found in the Afar region of northern Ethiopia four years ago.

The discovery shows that a second human ancestor lived in about the same area and time frame a Lucy’s species, researchers said.

However, not everyone agrees with that notion.

The journal Nature released a paper Wednesday announcing the new find and assigned it to a species they dubbed Australopithecus deyiremeda. In the Afar language the second name means “close relative,” referring to its apparent relationship to later members of the evolutionary tree.

Yohannes Haile-Selassie of the Cleveland Museum of Natural History, who led the discovery team, says nobody knows just how it’s related to our own branch of the family tree.

Previously, fossilized foot bones found in 2009 near the new discovery site had indicated the presence of a second species. But those bones were not assigned to any species, and it is still unclear whether they belong to the newly identified species, Haile-Selassie said. If they don't, that would indicate yet another species from the same time and region as Lucy's species, Australopithecus afarensis.

Bernard Wood of George Washington University said the discovery provides “compelling evidence” that a second creature lived in the vicinity of Lucy’s species at the same time. Wood wonders how they shared the landscape.

"These fossils certainly create an agenda for a lot of interesting research that's going to be done in the next decade," Wood said.

As evidence that the new fossils represent a previously unknown species, the researchers cite specific anatomical differences with known fossils. But Tim White, a University of California, Berkeley, expert in human evolution, was unimpressed.

He said he thinks the fossils actually come from Lucy's species.

"Anatomical variation within a biological species is normal," he said in an email to The Associated Press. "That's why so many announcements of this sort are quickly overturned."

The Associated Press contributed to this report.