From the time of the dinosaurs, the currently known fossil record fast-forwards in time to about 30 Ma. At present, there is a prolonged gap in the known deposits around the Turkana Basin, although Eocene and early Oligocene deposits are likely to be found with further exploration. Nevertheless, the time known as the late Oligocene—when the fossil trail picks up once more—marks the first appearance of Old World higher primates and is therefore of intense research interest.
After preliminary exploration at this age during the 1960s and 1980s and more recently in the last few years, three sites to the south-west of the lake and one a few miles north of TBI-Turkwel have already yielded important collections of late Oligocene mammalian faunas including early primates. The collections greatly enrich our understanding of this time interval, which was previously unknown in eastern Africa and informed only by the rich, but geographically restricted, collections from the Fayum in Egypt. At present, the Turkana sites are being explored by a French team led by Fabrice Lihoreau (Université of Montpellier) and Stéphane Ducrocq (Centre National de la Recherche Scientifique, CNRS), and an American team led by Tab Rasmussen (Washington University in St. Louis).
Two sites to the north-east of the lake close to the Ethiopian border, and several to the west are slightly younger and date to the early and middle Miocene (18-13 Ma). During this key interval, one species among many early apes began the long evolutionary journey that led to the common ancestor of all apes and humans alive today.
Currently, ongoing research out of TBI is focused on three early Miocene sites dating between 17 and 18 Ma with the goal to recover more complete remains of early apes and the mammals associated with them. James Rossie (Stony Brook University) is working out of TBI-Turkwel at Moruorot and at Kalodirr on the west side of Lake Turkana. Ellen Miller (Wake Forest University) is working out of TBI-Ileret at the similar aged site at Buluk, just south of the Ethiopian border. James Rossie is also surveying Esha, a 13 Ma middle Miocene site located close to Moruorot.