Fieldwork at the Pliocene site of Kantis, Kenya, has yielded fossilized teeth and forearm bone attributable to Australopithecus afarensis, a hominid species that lived from 3.85 to 2.95 million years ago.
Forensic facial reconstruction of Australopithecus afarensis. Image credit: Cicero Moraes / CC BY-SA 3.0.
The new fossils – from an adult male and two infant Australopithecus afarensis – suggest that this hominid species lived far eastward beyond the Great Rift Valley and much farther than previously thought.
The fossils all date to between 3.5 and 3.3 million years ago, according to a team of scientists led by Dr. Emma Mbua of Mount Kenya University and Dr. Masato Nakatsukasa of Kyoto University.
“Australopithecus afarensis was previously known from northern Ethiopia to northern Tanzania,” the researchers said. “The presence of A. afarensis in the Turkana basin of Kenya is contested.”
“The Kantis hominin specimens are the first clear evidence of this species in Kenya.”
“In addition, Kantis is unique in Kenya in its location on the eastern shoulder of the Gregory Rift Valley, hence expanding the A. afarensis range east of the Rift Valley.”
According to the team, the Kantis region was humid, but had a plain-like environment with fewer trees compared to other sites in the Great Rift Valley where Australopithecus afarensis fossils had previously appeared.
Australopithecus afarensis bone from Kenya. Eroded parts are shown with shading. Abbreviations: sp and arrow heads – supinator crest, ic – interosseous crest, br – insertion of the brachialis muscle, fd – origin of the flexor digitorum superficialis and pronator teres muscles. Scale – 5 cm. Image credit: Masato Nakatsukasa, Kyoto University.
“The hominid must have discovered suitable habitats in the Kenyan highlands,” Dr. Nakatsukasa said.
“It seems that A. afarensis was good at adapting to varying environments.”
The team’s survey also turned up masses of mammal fossils, including a few that probably belong to new species of bovids or baboons.
The Kantis fossils were described in the Journal of Human Evolution.
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Emma Mbua et al. 2016. Kantis: A new Australopithecus site on the shoulders of the Rift Valley near Nairobi, Kenya. Journal of Human Evolution, vol. 94, pp. 28-44; doi: 10.1016/j.jhevol.2016.01.006
