Ethiopia: discovery of the oldest Australopithecian fossil skull

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An international group of researchers has discovered an Australopithecus skull in an exceptional state of conservation. Unearthed in the region of Afar in Ethiopia, which had already offered Lucy, 55 kilometers away, this new fossil rebats a few cards in the history of humanity.

The maxillary, the frontal and parietal lobes, the nasal fossa, the orbits … everything is incredibly well preserved, despite 3.8 million years spent underground. This fossil is that of a Australopithecus Anamensis, the oldest species of this kind. Until then, it was estimated that they lived between 4.2 and 3.9 million years ago. This discovery rejuvenates this species of 100,000 years. It's little on this time scale, but it's not trivial. In the meantime, another species of Australopithecus has appeared: afarensis, whose Lucy is the most famous representative.

This new specimen therefore implies that the two species have been contemporaneous for at least a few tens of thousands of years, whereas the scientists thought until then that one had succeeded the other.

The fossilized skull of an Australopithecus Anamensis, the oldest species of this genus, found in Ethiopia.
                         © HO / CLEVELAND MUSEUM OF NATURAL HISTORY

It is all the more interesting that the very good state of conservation of the skull has allowed to reconstruct the face of this individual in synthetic image. We realize that he shares some traits with afarensisbut also with other older and primitive human groups like Ardipithecus and Sahelanthropus.

A dating made possible by minerals present in the soil

This 3.8 million-year dating was made possible by the analysis of minerals present in the volcanic rock layers that were in the excavation area. By combining observations made in the field with the study of microscopic biological remains found in the region, the researchers were also able to reconstruct the landscape and vegetation of the time.

The fossil skull has been found among the sandy deposits of a region where an old river has entered a lake that has disappeared. The tectonic movements of the Ethiopian Rift Valley then led over the millennia to the birth of the plains that characterize the region of Afar. Scientists have also discovered fossil pollen grains and remnants of plants and algae. They concluded that the lake was surrounded by wooded areas, a basin that was essentially dry and probably salty at certain times.

All these elements put end to end make it possible to better understand the evolutions of species that followed one another in the Australopithecus and from when the branches separated to form the genus Homo, ours. It has long been thought thatafarensis was one of the ancestors of Homo, but this assumption is now a minority: paleoanthropologists now believe that they have separated before.



Source link
http://www.rfi.fr/afrique/20190828-ethiopie-decouverte-plus-vieux-fossile-australopitheque

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