Early Pliocene hominids from Gona, Ethiopia.
Comparative biomolecular studies suggest that the last common ancestor of humans and chimpanzees, our closest living relatives, lived during the Late Miocene-Early Pliocene. Fossil evidence of Late Miocene-Early Pliocene hominid evolution is rare and limited to a few sites in Ethiopia, Kenya and Chad. Here we report new Early Pliocene hominid discoveries and their palaeoenvironmental context from the fossiliferous deposits of As Duma, Gona Western Margin (GWM), Afar, Ethiopia. The hominid dental anatomy (occlusal enamel thickness, absolute and relative size of the first and second lower molar crowns, and premolar crown and radicular anatomy) indicates attribution to Ardipithecus ramidus. The combined radioisotopic and palaeomagnetic data suggest an age of between 4.51 and 4.32 million years for the hominid finds at As Duma. Diverse sources of data (sedimentology, faunal composition, ecomorphological variables and stable carbon isotopic evidence from the palaeosols and fossil tooth enamel) indicate that the Early Pliocene As Duma sediments sample a moderate rainfall woodland and woodland/grassland.
Semaw
Sileshi
S
CRAFT Stone Age Institute, Indiana University, 1392 West Dittemore Road, Gosport, Indiana, 47433-9531, USA. ssemaw@indiana.edu
Simpson
Scott W
SW
Quade
Jay
J
Renne
Paul R
PR
Butler
Robert F
RF
McIntosh
William C
WC
Levin
Naomi
N
Dominguez-Rodrigo
Manuel
M
Rogers
Michael J
MJ
D000818:Animals; D003743:Dental Enamel / Q000737:chemistry; D004777:Environment; D005002:Ethiopia; D005580:Fossils; D049690:History, Ancient; D015186:Hominidae / Q000033:anatomy & histology*; D007568:Jaw / Q000033:anatomy & histology; D006109:Poaceae; D011891:Rain; D013997:Time Factors; D014070:Tooth / Q000033:anatomy & histology / Q000737:chemistry; D014197:Trees