near and on the river, including hippopotamuses, crocodiles and puff adders. Archaeological findings The entire Omo river basin is also important geologically and archaeologically. Over 50,000 fossils have been identified from the lower valley, including 230 hominid fossils dating to the Pliocene and Pleistocene. Fossils belonging to the genera Australopithecus and Homo have been found at several archaeological sites, as well as tools made from quartzite, the oldest of which date back to about 2.4 million years ago. When they were discovered, it was thought that the tools might have been part of a so-called pre-Oldowan industry, even more primitive than what was found in the Olduvai Gorge. Later research has shown that the crude looks of the tools were in fact caused by very poor raw materials, and that the techniques used and the shapes permit their inclusion in the Oldowan. The first archaeological discoveries in the area were in 1901, by a French expedition. The most significant finds were made later, between 1967 and 1975, by an international archaeological team. This team located a number of different items, including the jawbone of an Australopithecus man, estimated at some 2.5 million years old. Archeologists have also found fossil fragments of Olduwan hominids from the early Pleistocene era and up to the Pliocene era. Quartz tools have been located with some of the later Homo sapiens remains found on the riverbanks. Since then, the excavations have been carried out by a joint French and American team. In addition to early hominid fossils, a diversity of mammal and fish fossils have been found within the Omo Valley. Human impact The lower valley of the Omo is currently believed by some to have been a crossroads for thousands of years as various cultures and ethnic groups migrated around the region. To this day, the people of the Lower Valley of the Omo, including the Mursi, Suri, Nyangatom, Dizi and Me'en, are studied for their diversity. Italian explorer Vittorio Bottego first reached the Omo river on 29 June 1896 during his second African expedition (1895–97), dying during this expedition on 17 March 1897. The Omo river was renamed Omo-Bottego in his honour. Herbert Henry Austin and his men reached the Omo delta on 12 September 1898, and found that an Ethiopian expedition, led by Ras Wolda Giyorgis, had previously planted Ethiopian flags on the northern shore of Lake Turkana on 7 April, as