Fossilized teeth and a forearm bone that were recently unearthed in Kenya suggest that an early hominid species - Australopithecus afarensis - lived much farther east than previously believed. The dig also revealed what could be a new species of baboon.
This discovery was led by paleontologists Emma Mbua of Mount Kenya University and Masato Nakatsukasa of Kyoto University. It is believed that the newly found fossils belonged to an adult male and two infant A. afarensis, which were extinct hominins that lived between 3.9 and 2.9 million years ago.
Surprisingly, the remains were recovered from an exposure eroded by the Kantis River in Ongata-Rongai, a settlement in the outskirts of Nairobi, far eastward beyond the Great Rift Valley.
"So far, all other A. afarensis fossils had been identified from the center of the Rift Valley," Nakatsukasa explained. "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."
A. afarensis is one of the better-known australopithecines due to a remarkable amount of fossils, namely a partial skeleton of one 3.2 million-year-old hominin from Ethiopia named "Lucy."
Stable isotope analyses of the newly discovered forearm and fossil teeth revealed that the Kantis region was humid at the time in which the species existed. Compared to other sites in the Great Rift Valley where A. afaransis fossils have previously been found, this region had fewer trees and resembled more of a plain-like environment.
"The hominid must have discovered suitable habitats in the Kenyan highlands. It seems that A. afaransis was good at adapting to varying environments," Nakatsukasa added.
The team also recovered masses of mammal fossils during the dig, including a few that likely belong to new species of bovids or baboons. Researchers note that this find has significant implications not only for the evolution of humans, but also for the local community.
"Kantis is in the vicinity of Nairobi, a major city," Nakatsukasa said. "We hope that the discovery of the new site and the fossils will aid in increasing tourism, and in improving educational awareness of the local community."
Their study was recently published in the Journal of Human Evolution.
