埃塞俄比亚发现新种人类祖先

Cleveland . . . A new relative joins "Lucy" on the human family tree. An international team of scientists, led by Dr. Yohannes Haile-Selassie of The Cleveland Museum of Natural History, has discovered a 3.3 to 3.5 million-year-old new human ancestor species. Upper and lower jaw¹ fossils recovered from the Woranso-Mille area of the Afar region of Ethiopia have been assigned to the new species Australopithecus deyiremeda. This hominin lived alongside the famous "Lucy's" species, Australopithecus afarensis. The species will be described in the May 28, 2015 issue of the international scientific journal Nature. Lucy's species lived from 2.9 million years ago to 3.8 million years ago, overlapping² in time with the new species Australopithecus deyiremeda. The new species is the most conclusive³ evidence for the contemporaneous presence of more than one closely related early human ancestor species prior to 3 million years ago. The species name "deyiremeda" (day-ihreme-dah) means "close relative" in the language spoken by the Afar people.   Australopithecus deyiremeda differs from Lucy's species in terms of the shape and size of its thick-enameled teeth and the robust⁴ architecture of its lower jaws⁵. The anterior⁶ teeth are also relatively⁷ small indicating that it probably had a different diet.    "The new species is yet another confirmation⁸ that Lucy's species, Australopithecus afarensis, was not the only potential human ancestor species that roamed in what is now the Afar region of Ethiopia during the middle Pliocene," said lead author and Woranso-Mille project team leader Dr. Yohannes Haile-Selassie, curator of physical anthropology⁹ at The Cleveland Museum of Natural History. "Current fossil evidence from the Woranso-Mille study area clearly shows that there were at least two, if not three, early human species living at the same time and in close geographic¹⁰ proximity¹¹."    "The age of the new fossils is very well constrained¹² by the regional geology, radiometric dating, and new paleomagnetic data," said co-author Dr. Beverly Saylor of Case Western Reserve University. The combined evidence from radiometric, paleomagnetic, and depositional rate analyses yields estimated minimum and maximum ages of 3.3 and 3.5 million years.