Little Foot, Our Oldest Ancestor, Is Older Than Previously Thought
Little Foot, the nickname given to the Australopithecus fossil discovered in South Africa, is not as young as it was previously believed. Little Foot's age has been controversial since its discovery in 1997, and had been estimated to be around 2.2 million years old. But after 13 years of investigations on the nearly complete skeleton, a team of international scientists have concluded that Little Foot may be more around three million years old.
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Professor Ron Clarke, from the University of the Witwatersrand, and colleagues write about the fossil's age in a new paper, titled "Stratigraphic analysis of the Sterkfontein StW 573 Australopithecus Skeleton and Implications for its Age," which was published recently in the Journal of Human Evolution.
The Sterkfontein Caves of Gauteng, South Africa have become known as the "Cradle of Humankind," as scientists have discovered many fossils of early humans - the first australopithecine fossil found in the cave was discovered 1936 - including that of the famous Mrs Ples (Australopithecus africanus). These fossils were uncovered from the calcified ancient caves by blasting, drilling, and breaking the infill, as well as by using a pick and shovel. For many years, scientists only found bone fragments, including partial skulls and jaws, isolated teeth, and limbs.
The search for a complete australopithecine came to an end in 1997, when Ron Clarke, Stephen Motsumi, Nkwane Molefe, who were also from the university, discovered an almost complete Australopithecus skeleton with the skull embedded in hard, calcified sediment in an underground chamber of the caves. This fossil was carefully excavated to in order to understand its place in the evolutionary timeline, and to understand the factors that led to its careful preservation in the cave.
During the course of this excavation, it became clear that the skeleton had suffered trauma due to a partial collapse of its lower cavity and that sheet-like deposits of calcite called flowstone had subsequently filled the spaces formed around the displaced bones. Some researchers, however, had estimated the age of the skeleton by determining the age of the flowstone, assuming that the skeleton would be the same age.
Using the research from Clarke's study, a French team of specialists from Wits University found that the flowstones filled voids in the cave after erosion and collapse, and that the skeleton was there long before. Because of that, Little Foot may actually be 3 million years old, and therefore, hold the distinction of being our oldest ancestor - it's certainly the oldest complete Australopithecus discovered.
The skeleton is almost completely excavated and cleaned of the surrounding calcified deposits. Clarke recently that Little Foot belongs to the Australopithecus Prometheus species, first named by Professor Raymond Dart in 1948.
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