OMO REMAINS

group of hominid fossils, the oldest of which are about 3,000,000 years old, found by Yves Coppens, Camille Arambourg, F. Clark Howell, and others on the International Paleontological Research Expedition in the Omo River region of Ethiopia from 1967 to 1974. The remains consist of about 200 teeth, four jaws, a partial skeleton, parts of two skulls, and a leg bone. These fossil finds represented a great breakthrough in the study of early hominids because they were the first ones found to extend back to 3,000,000 years. Until they were uncovered, the earliest fossils were dated at about 1,750,000 years. The Omo River region is rich in early fossil remains because the area was once a highly volcanic one in which the strata of the earth were heaved up and now lie at angles to the Earth's surface. The layers of ash, easily dated by the potassium-argon method, reveal that the area, now an arid wasteland, was once a fertile region with several rivers and lush forests. The remains consist of specimens of Paraustralopithecus aethiopicus, Australopithecus africanus, Australopithecus boisei, and Homo erectus. There is evidence that Australopithecus boisei, not viewed as in the direct line of evolution to modern man, lived in the Omo region for at least 1,000,000 years. Various stone tools dating back to the earliest stone tool industry were found alongside the fossils.