The pelvis and femur of Ardipithecus ramidus: the emergence of upright walking.

Bibliographic Collection: 
MOCA Reference, APE
Publication Type: Journal Article
Authors: Lovejoy, C Owen; Suwa, Gen; Spurlock, Linda; Asfaw, Berhane; White, Tim D
Year of Publication: 2009
Journal: Science
Volume: 326
Issue: 5949
Pagination: 71e1-6
Date Published: 10/2009
Publication Language: eng
ISSN: 1095-9203
Keywords: Animals, Biological Evolution, Ethiopia, Femur, Fossils, Hominidae, Ilium, Ischium, Locomotion, Pelvic Bones, pelvis, Posture, Pubic Bone, Ribs, Spine, Thorax, Walking

The femur and pelvis of Ardipithecus ramidus have characters indicative of both upright bipedal walking and movement in trees. Consequently, bipedality in Ar. ramidus was more primitive than in later Australopithecus. Compared with monkeys and Early Miocene apes such as Proconsul, the ilium in Ar. ramidus is mediolaterally expanded, and its sacroiliac joint is located more posteriorly. These changes are shared with some Middle and Late Miocene apes as well as with African apes and later hominids. However, in contrast to extant apes, bipedality in Ar. ramidus was facilitated by craniocaudal shortening of the ilium and enhanced lordotic recurvature of the lower spine. Given the predominant absence of derived traits in other skeletal regions of Ar. ramidus, including the forelimb, these adaptations were probably acquired shortly after divergence from our last common ancestor with chimpanzees. They therefore bear little or no functional relationship to the highly derived suspension, vertical climbing, knuckle-walking, and facultative bipedality of extant African apes.

Alternate Journal: Science
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