Ledi-Geraru strikes again: morphological affinities of the LD 350-1 mandible with early Homo

Abstract

The origins of the genus Homo have been a focus of much debate in the paleoanthropological literature due to its importance in understanding the evolutionary trajectories that led to the appearance of archaic humans and our species. On the level of taxonomic classification, the controversies surrounding the origins of Homo are the result of lack of clear classification criteria that separate our genus from australopiths, given the general similarities observed between fossils ascribed to late australopiths and early Homo. The challenge in finding clear autapomorphies for Homo has even led to debates about the classification of Homo habilis and Homo rudolfensis as part of our genus. These debates are further complicated by the scarcity of fossils in the timeframe of appearance of our genus, making any fossils dated to between 3.0 and 2.5 Ma of particular relevance in the context of this discussion. The Ledi-Geraru mandible is one such fossils, which has called the attention of researchers due to its combination of primitive traits seen in Australopithecus and derived traits observed in later Homo. Despite being fragmented and poorly preserved, it is one of the key fossil specimens available from the period mentioned above.