New fossils from Kenya suggest that an early hominid species —
Australopithecus afarensis — lived far eastward beyond the Great Rift
Valley and much farther than previously thought. An international team
of paleontologists led by Emma Mbua of Mount Kenya University and
Masato Nakatsukasa of Kyoto University report findings of fossilized
teeth and forearm bone from an adult male and two infant A. afarensis
from an exposure eroded by the Kantis River in Ongata-Rongai, a
settlement in the outskirts of Nairobi.
"So far, all other A. afarensis fossils had been identified from
the center of the Rift Valley," explains Nakatsukasa. "A previous
Australopithecus bahrelghazali discovery in Chad confirmed that
our hominid ancestor's distribution covered central Africa, but
this was the first time an Australopithecus fossil has been found
east of the Rift Valley. This has important implications for what
we understand about our ancestor's distribution range, namely that
Australopithecus could have covered a much greater area by this
age."
...
Stable isotope analysis revealed that the Kantis region was humid,
but had a plain-like environment with fewer trees compared to other
sites in the Great Rift Valley where A. afaransis fossils had
previously appeared. "The hominid must have discovered suitable
habitats in the Kenyan highlands. It seems that A. afaransis was
good at adapting to varying environments," notes Nakatsukasa.
...
http://www.sciencedirect.com/
Kantis: A new Australopithecus site on the shoulders of the
Rift Valley near Nairobi, Kenya
Abstract
Most Plio-Pleistocene sites in the Gregory Rift Valley that have
yielded abundant fossil hominins lie on the Rift Valley floor. Here
we report a new Pliocene site, Kantis, on the shoulder of the
Gregory Rift Valley, which extends the geographical range of
Australopithecus afarensis to the highlands of Kenya. This species,
known from sites in Ethiopia, Tanzania, and possibly Kenya, is
believed to be adapted to a wide spectrum of habitats, from open
grassland to woodland. The Kantis fauna is generally similar to that
reported from other contemporaneous A. afarensis sites on the Rift
Valley floor. However, its faunal composition and stable carbon
isotopic data from dental enamel suggest a stronger C4 environment
than that present at those sites. Although the Gregory Rift Valley
has been the focus of paleontologists' attention for many years,
surveys of the Rift shoulder may provide new perspective on African
Pliocene mammal and hominin evolution.
-Thanks to Rick Trasky for these articles.
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