Human Evolution @ UCL


Gona, Ethiopia: New 4.8 to 4.3 million year old partial skeleton of Ardipithecus ramidus announced

8 February 2019

Functional analyses of the 4.

4 Ma hominin Ardipithecus ramidus postcrania revealed a previously unknown and unpredicted locomotor pattern combining arboreal clambering and a form of terrestrial bipedality. To date, all of the fossil evidence of Ar. ramidus locomotion has been collected from the Aramis area of the Middle Awash Research Project in Ethiopia. Here, we present the results of an analysis of additional early Pliocene Ar. ramidus fossils from the Gona Project study area, Ethiopia, that includes a fragmentary but informative partial skeleton (GWM67/P2) and additional isolated manual remains. While we reinforce the original functional interpretations of Ar. ramidus of having a mixed locomotor adaptation of terrestrial bipedality and arboreal clambering, we broaden our understanding of the nature of its locomotor pattern by documenting better the function of the hip, ankle, and foot. The newly recovered fossils document a greater adaptation to bipedality in the Ar. ramidus ankle and hallux than previously recognized. In addition, a newly discovered scaphoid bone with a fusing os centrale provides further evidence about the nature of hominin hand evolution.

Figure 4 - GWM3-P2 manual proximal phalanx fragment. A. Dorsal. B. Palmar. C. Basal (proximal). Scale bar A and B = 10 mm. Scale bar C = 5 mm.

Comparison of the GWM67/P2k and ARA-VP-6/500-089 first metatarsals in dorsal view.

GWM10/P1 manual proximal phalanx.

GWM5sw/P58 manual intermediate phalanx fragment.

GWM67/P2a left distal tibia fragment.

GWM67/P2d left distal fibula fragment.

GWM67/P2c right distal calcaneus fragment.

GWM67/P2h right lateral cuneiform fragment.

Ardipithecus ramidus postcrania from the Gona Project area, Afar Regional State, Ethiopia

Scott W. Simpson, Naomi E. Levin, Jay Quade, Michael J. Rogers, Sileshi Semaw

DOI: 10.1016/j.jhevol.2018.12.005