Two 1.9 million-year-old skeletons found in a South African cave have added a new and intriguing member to the primate family.

Dubbed Australopithecus sediba, it has many features — including long legs and a protruding nose — common to Homo, the genus that eventually spawned humans. Other features, such as extra-long forearms and flexible feet, date from deep in our primate past.

Paleontologists disagree over whether A. sediba is a direct human ancestor, or just looks like one. But whatever their lineage, the fossils provide rare insight into a period shrouded in paleontological mystery.

“We feel that A. sediba might be a Rosetta Stone for defining for the first time what the genus Homo is,” said paleontologist Lee Berger of the University of Witwatersrand. “They’re going to be a remarkable window, a time machine.”

Wired: Possible New Human Ancestor Discovered

More on the discovery: New York Times: New Hominid Species Discovered in South Africa