NEW FOSSIL FROM CHAD EXTENDS THE RANGE OF AUSTRALOPITHECINES

Philip L. Stein and Bruce M. Rowe

Number 3, Spring 1996

See Physical Anthropology: The Core, Chapter 10, pages 238, 248;

Physical Anthropology, 6^th edition, Chapter 16, pages 406, 418.

Fossil mammals, including fossil hominids from east and south Africa, are among the most well-known discoveries to date. This high frequency of finds has led many paleontologists to conclude that some forms, such as the australopithecines, only existed in the eastern and southern regions of the African continent. Yet the reconstruction of the distribution of prehistoric animals from the locations of known fossils can be misleading. Fossilization and the exposure of fossils are much more apt to occur under certain geological conditions than others. This leads to the conclusion that the distribution of fossils is more a matter of geology than a matter of the distribution of the once living species.

It is probable that the australopithecines occupied larger areas of Africa than is indicated by the known fossil record. The announcement in late 1995 that australopithecine fossils have been recovered in northern Chad, some 2500 kilometers (1550 miles) west of the Rift Valley is, therefore, of great interest.¹

The presence of Pliocene and Pleistocene mammalian fossils in central Africa was reported in 1959. In 1993 seventeen new sites were discovered in the region of Bahr el Ghazal near Koro Toro in the Borkou-Ennedi-Tibesti Province of northern Chad.

An australopithecine mandible has been recovered from the site known as KT 12. The find is associated with other animal fossils that have been dated between 3.5 and 3.0 million years old. This new hominid fossil, KT 12/H1, is a fragment of an adult mandible and includes the crowns of several teeth.

The fossil resembles Australopithecus afarensis in many ways, yet differs from other specimens of this species in some features. The discoverers have not as yet decided whether these differences represent geographical variation of A. afarensis or represent a new australopithecine species.