A. sediba – New reports

Age pinpointed with new paleomagnetic data

Biology News

Australopithecus sediba — The U.W. 88-50 (MH1) cranium,juvenile male. Photo: Brett Eloff courtesy of Lee Berger, Univ. of Witwatersrand (click to enlarge)

Researchers have determined the age of A. sediba, the most recent australopithecine, with greatly improved accuracy at 1.98 million years (± 3,000 years).

This new finding means that the remains of Australopithecus sediba, found in a cave at Malapa, South Africa in 2008, are now among the most precisely dated fossils of early humans.

Papers published today in a special issue of the journal Science describe the new findings, as well as more detailed studies of the hands, feet, pelvis and brain.

Uranium-lead dating of the flowstone, combined with palaeomagnetic analysis sediments surrounding the fossils, provide the tightly constrained new age.

The team was able to pin down the age of the fossils to within 3000 years of 1.98 million years, a big advance over the previous estimated age range of around 200,000 years.

Robyn Pickering, of the University of Melbourne, a researcher involved in the dating of the flowstone surrounding the fossils said researchers had long been searching for fossils from this time period to answer questions about human origins.

"Knowing the age of the fossils is critical to placing them in our family tree."

"The results of these studies present arguably the most precise dates ever achieved for any early human fossils," she said.

The fossils were deposited in the Malapa Cave during a period when the Earth's magnetic field reversed itself by 180 degrees and back again.

Andy Herries, of La Trobe University, who did the palaeomagnetic analysis, says such methods will "enable us to better date fossil and archaeological sites in the future, as well as to understand the possible effects they have on climate, plants and animals."