The creatures most likely fell into a 50 metre-deep cave soon after the start of a period of 'normal' magnetic polarity around 1.95 million years ago, the scientists found.
"Until recently it was impossible to get precise dates for the South African cave sites, but with the development of new techniques we are beginning to understand the relationships of the various species of early human to each other," said Dr Herries.
"This is a period of major climatic change and increasing aridity in Africa, when a number of different early human species occur that are potential ancestors to Homo erectus, each adapting to these changes in different ways. Australopithecus sediba appears to have traits of both the earlier species, Australopithecus africanus, and a later species, Homo erectus," he said.
Traits of modern humans
Information from the skeletons shows Au. sediba was an upright walker, around 1.27 meters tall, and shared many of the physical traits of the earliest humans, including a prominent nose and powerful hands that could have made and used stone tools. Its brain was still relatively small, but it had long legs and an advanced hip and pelvis that would have given it more modern locomotion similar to Homo erectus and modern humans, the scientists said.
"The discovery of so many partial skeletons from a single site is unprecedented. It enables us to understand the full skeletal anatomy of these early human ancestors rather than relying on fragments of a skull or some teeth, which can sometimes be misleading," Dr Herries said.
To date, only preliminary excavations have been carried out at the site; however in the months since the Science paper was submitted more remains have been discovered al
|Contact: Stephen Offner|
University of New South Wales