Researchers analyzing fossils uncovered in the outskirts of Nairobi reveal that they belonged to the same species as Lucy, Australopithecus afarensis . This is the first time a fossil from this extinct genus was detected east of the Rift Valley, suggesting that the range of our Australopithecus ancestors was much bigger than we supposed. The findings are published in the May issue of Journal of Human Evolution.
A. afarensis is known from East African sites dating back between 3.7 and 3million years. They lived in a broad spectrum of habitats from northern Ethiopia to northern Tanzania, including woodlands at Laetoli, mixed woodland and shrubland at Hadar, and floodplain grassland at Maka. Now, according to a team led by Mount Kenya Universitys Emma Mbua and Masato Nakatsukasa of Kyoto University, A. afarensis also lived much farther east in the highlands of Kenya at what theyve now named the Kantis Fossil Site.
Located on the eastern shoulder of the Gregory Rift Valley, the Kantis bone bed was noted during a geological survey in 1991. However , no research had been conducted until 2009, when the owner of a farm next to the small, seasonal Kantis river reported the site to researchers. The farm proprietors family had considered fossilized bones on the dry Kantis valley back in the 1970 s.
In the last few years, the team has collected 1,200 fossil components from the Kantis Fossil Site are subordinate to 28 animal groups and one human ancestor. Theyve identified a few A. afarensis teeth and one forearm representing two adolescents and an adult. Based on the sizing and development of muscle attachment marks, the left ulna( KNM-RK 53525, pictured above) likely came from an adult male. “This has important implications for what we understand about our ancestor’s distribution range, ” Nakatsukasa tells in a statement, “namely that Australopithecus could have encompassed a much greater region by this age.”
The team also identified the remaining fossil hippos, rhinos, horses, giraffes, elephants, and cats. The composition of the Kantis fauna, be included with stable carbon isotopic data, suggest that this site 3.5 million years ago was like that of other A. afarensis sites on the Rift Valley floor, but most open. It was mostly grassland with a perennial body of water and few trees.
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