Among the most important findings:
-Ardipithecus, and in particular fossils of Ardipithecus kadabba (dated between 5,54 and 5,77 million years b.p.) and Ardipithecus ramidus (dated between at 4,4 million years b.p);
-Australopithecus, and in particular fossils of Australopithecus anamensis (dated at around 4.1 million years b.p.), Australopithecus afarensis (the most famous fossil of this species is the partial skeleton named Lucy -3.2 million years old- found by Donald Johanson and colleagues at Hadar in the Awash Valley) and later species (A. africanus, A. garhi);
-genus Homo, and in particular fossils of Homo habilis (dated at 2.3 million years b.p.), Homo erectus (differentiated from Habilis at around 1,5 million years b.p.), Homo sapiens (fossils dated at around 155,000 years b.p.).
The transition between Homo erectus and the subsequent Homo sapiens is still highly debated. The most accepted theory suggests that the Homo sapiens differentiated from the erectus in Africa; subsequently, Homo sapiens would have given rise to a sub-species, the modern Homo sapiens sapiens, able to migrate (at around 60,000-70,000 years b.p.) out of Africa and to colonize the other continents substituting other local, more primitive populations (such as the Homo neanderthalensis in Europe).