Ardipithecus ramidus, a bipedal hominid, also swung from trees and sometimes walked on all fours AND lived in woodlands rather than on the plains as was previously thought.
In its 2 October 2009 issue, Science journal ( http://www.sciencemag.org/cgi/content/abstract/323/5918/1197 ) presents 11 papers, authored by a diverse international team, describing an early hominid species, Ardipithecus ramidus, and its environment. These 4.4 million year old hominid fossils sit within a critical early part of human evolution, and cast new and sometimes surprising light on the evolution of human limbs and locomotion, the habitats occupied by early hominids, and the nature of our last common ancestor with chimps.
Ardi has an opposable toe (left) and flexible hand (right); her canines (top center) are sized between those of a human (top left) and chimp (top right); and the blades of her pelvis (lower left) are broad like Lucy's (yellow).
Now, in a special section beginning on page 60 and online, a multidisciplinary international team presents the oldest known skeleton of a potential human ancestor, 4.4-million-year-old Ardipithecus ramidus from Aramis, Ethiopia.
This remarkably rare skeleton is not the oldest putative hominin, but it is by far the most complete of the earliest specimens. It includes most of the skull and teeth, as well as the pelvis, hands, and feet-parts that the authors say reveal an "intermediate" form of upright walking, considered a hallmark of hominins. "We thought Lucy was the find of the century but, in retrospect, it isn't," says paleoanthropologist Andrew Hill of Yale University. "It's worth the wait."