New stratigraphic research makes Little Foot the oldest complete Australopithecus
PARIS—He may be called Little Foot, but for human evolution researchers he’s a big deal: His is the most complete skeleton known of an early member of the human lineage. Ever since the skeleton was discovered in a South African cave in the 1990s and named for its relatively small foot bones, researchers have been fiercely debating how old it is, with estimates ranging from about 2 million years to more than 3 million. A new geological study of the cave concludes that Little Foot is at least 3 million years old. If correct, that would mean he is old enough to be a direct ancestor of today’s humans, and could shift South Africa to the forefront of human evolution.
The first traces of the skeleton were found in the early 1990s by Ron Clarke, a paleoanthropologist at the University of the Witwatersrand in Johannesburg, South Africa. He was rummaging through boxes of animal bones previously excavated in the Sterkfontein caves, about 40 kilometers northwest of Johannesburg, where a number of fossils of australopithecines—advanced apes similar to the famous Lucy—have been discovered. Clarke found four small australopithecine foot bones, and set off with his team to unearth the skeleton that they came from.
In 1997, they found it, deeply embedded in rock that had formed after Little Foot apparently fell 20 meters into the cave through a hole in the ground above. Virtually the entire skeleton was preserved down to the smallest finger and toe bones, an extremely rare event. (Lucy, for example, is only about 40% complete.) It took more than 15 years to excavate the fragile fossils from the rock.
Several teams tried to determine the age of the skeleton by dating the rocks around it, using techniques based either on the earth’s magnetic field or the decay of uranium in the rocks. (The bones are far too old for radiocarbon dating, which cannot peer back further than about 45,000 years.) Clarke’s team estimated Little Foot to be about 3.3 million years old—about as old as Lucy, found in East Africa. And although its anatomical details have yet to be published in detail, Clarke says Little Foot appears to be somewhat closer to later humans than Lucy: While its skull is primitive like Lucy’s, its hands are more modern, and its feet have both apelike and human features.
http://news.sciencemag.org/africa/2014/03/little-foot-fossil-could-be-human-ancestor
Also here:
http://phys.org/news/2014-03-stratigraphic-foot-oldest-australopithecus.html
