New Human Ancestor Discovered Near Fossil of “Lucy”

Welcome, Lucy's neighbour. Fossilized jaws and teeth found in northern Ethiopia belong to an ancient human ancestor that researchers say lived around the same time as Lucy's kind, Australopithecus afarensis, but is a distinct species. The remains of the new species, which has been dubbed Australopithecus deyiremeda and lived between 3.5 million and 3.3 million years ago, were uncovered just 35 kilometres from the Hadar site at which Lucy and other A. afarensis individuals were found. Fossils from A. afarensis date to between 3.7 and 3 million years ago, so the two species would have overlapped (though Lucy herself may have lived too recently to see one).
The find suggests that several distinct hominins—species more closely related to humans than to chimps—roamed eastern Africa more than 3 million years ago. A third species, Kenyanthropus platyops, lived in what is now Kenya around the same time. “The question that is going to come up is which taxa gave rise to our genus, Homo,” says Yohannes Haille-Selassie, a palaeoanthropologist at the Cleveland Museum of Natural History in Ohio, whose team reports its discovery in Nature. “That’s going to be the 64-million-dollar question.”

Odd one out
The researchers did not realize the significance of the remains when they found a lower and upper jaw in March 2011, on what was supposed to be the final day of their field season exploring the arid Woranso-Mille area in northern Ethiopia. “That forced us to extend our field stay,” says Haille-Selassie.

Given the close proximity of Hadar, which has yielded hundreds of fossils belonging to A. afarensis, including Lucy’s relatively complete remains, the team guessed that the bones belonged to that species. But closer inspection revealed that the lower jaw was beefier, and the teeth smaller, than those of the hominin's Hadar neighbours. Neither did K. platyops—defined by a flat-faced 3.5-million-year-old skull found near Lake Turkana, Kenya—prove a compelling match.



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http://www.scientificamerican.com/article/new-human-ancestor-discovered-near-fossil-of-lucy/