A. garhi

''Australopithecus garhi'' is a species of australopithecine from the Bouri Formation in the Afar Region of Ethiopia 2.6–2.5 million years ago (mya) during the Early Pleistocene. The first remains were described in 1999 based on several skeletal elements uncovered in the three years preceding. ''A. garhi'' was originally considered to have been a direct ancestor to ''Homo'' and the human line, but is now thought to have been an offshoot. Like other australopithecines, ''A. garhi'' had a brain volume of ; a jaw which jutted out (prognathism); relatively large molars and premolars; adaptations for both walking on two legs (bipedalism) and grasping while climbing (arboreality); and it is possible that, though unclear if, males were larger than females (exhibited sexual dimorphism). One individual, presumed female based on size, may have been tall.

''A. garhi'' is the first pre-''Homo'' hominin postulated to have manufactured tools—using them in butchering—and may be counted among a growing body of evidence for pre-''Homo'' stone tool industries (the ability to manufacture tools was previously believed to have separated ''Homo'' from predecessors.) ''A. garhi'' possibly produced the Oldowan industry which was previously considered to have been invented by the later '' H. habilis'', though this may have instead been produced by contemporary ''Homo''.

Taxonomy

The Ethiopian ''Australopithecus garhi'' was first described in 1999 by palaeoanthropologists Berhane Asfaw, Tim D. White, Owen Lovejoy, Bruce Latimer, Scott Simpson, and Gen Suwa based on fossils discovered in the Hatayae Beds of the Bouri Formation in Middle Awash, Afar Region, Ethiopia. The first hominin remains were discovered here in 1990—a partial parietal bone (GAM-VP-1/2), left jawbone (GAM-VP-1/1), and left humerus (MAT-VP-1/1)—which are unassignable to a specific genus. The first identifiable ''Australopithecus'' fossils–an adult ulna (BOU-VP-11/1)–were found on 17 November 1996 by T. Assebework. A partial skeleton (BOU-VP-12/1) was discovered 13 days later by White, comprising a mostly complete left femur, right humerus, radius, and ulna, and a partial fibula, foot, and jawbone. The holotype specimen, a partial skull (BOU-VP-12/130), was discovered on 20 November 1997 by Ethiopian palaeoanthropologist Yohannes Haile-Selassie. More skull fragments (BOU-VP-12/87) were recovered south of BOU-VP-12/1. On 17 November 1997, French palaeoanthropologist Alban Defleur discovered a complete mandible (BOU-VP-17/1) about north in the Esa Dibo locality of the formation, and American palaeoanthropologist David DeGusta discovered a humerus (BOU-VP-35/1) north of BOU-VP-17/1. However, BOU-VP-11, -12, and -35 cannot conclusively be attributed to ''A. garhi''.

The remains are dated to about 2.5 million years ago (mya) based on argon–argon dating. When they were discovered, human evolution was obscured due to a paucity of remains from 3 to 2 mya, with the only hominins from this timespan being identified from South Africa ('' A. africanus'') and Lake Turkana, Kenya (''Paranthropus aethiopicus''). Likewise, the classification of australopithecines and pre-''Homo erectus'' hominins has been the subject of much debate. The original describers considered ''A. garhi'' to be a descendant of the earlier ''A. afarensis'' which inhabited the same region, based mainly on dental similarities. Though they assigned the species to ''Australopithecus'', the original describers believed it could represent an ancestor to ''Homo'', which, if the case, would possibly lead to reclassification as ''H. garhi''. Because the characteristics of ''A. garhi'' are unexpected for a human ancestor at this stage, the specific name, ''garhi'', means "surprise" in the local Afar language