Thursday, April 08, 2010

Australopithecus sediba: Another New Hominid from South Africa

Australopithecus sediba: A New Species of Homo-Like Australopith from South Africa. 2010. L.R. Berger, et al. Science 328: 195-204.

A transparent cranial reconstruction showing dental pattern, upper left, a modified reconstruction of the juvenile skull, center, and the actual fossil cranium from A. sediba.
The fossils of Australopithecus sediba are between 1.95 and 1.78 million years old, and show that the new species was an upright walker that shared many physical traits with the earliest known Homo species.

These new fossils are approximately one million years younger than the famous Australopithecus, Lucy, and their features imply that the transition from earlier hominids to the Homo genus occurred in very slow stages, with various Homo-like species emerging first.

The fossil remains of the two hominids were found about a half-meter apart, embedded in cave deposits at the Malapa excavation site located about 170 miles northeast of Johannesburg and about nine miles northeast of the Sterkfontein World Heritage Site, also called the Cradle of Humankind. The first adult australopithecine was found in Sterkfontein in 1936.

It is not possible to establish the precise phylogenetic position of Australopithecus sediba in relation to various species assigned to early Homo. The new species shares more derived features with early Homo than any other known australopith species, and thus represents a candidate ancestor for the genus, or a sister group to a close ancestor that persisted for some time after the first appearance of Homo."

The researchers describe the hominid's physical traits, highlighting the unique pelvic features and small teeth that it shared with early Homo species. Based on its physique, they suggest that the new species descended from Australopithecus africanus, and that the hominid's appearance signified the dawn of more energy-efficient walking and running. link