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.”
The skeletons, described April 8 in Science, were found — with a bit of help from Google Earth — two years ago in a South African cave, where they fell two million years ago.
On one side of that date in the fossil timeline are the various species of Australopithecus, the first great apes to walk on two feet. On the timeline’s other side is the genus Homo, the first creatures one would recognize — with all due respect to Lucy’s famous A. afarensis — as close to human.
In between is uncertainty. The fossil record is mostly bare. Some of the Australopithecus lineage split, with one branch becoming Homo. But the identity of that lineage, and the characteristics of early Homo, are unknown.