B47
The pelvis of Ardipithecus ramidus
a mosaic of human and ape features

The Ar. ramidus innominate is a rare instance that preserves significant portions of all three bones, the ilium, ischium and pubis. However, fragmentation, displacement and plastic deformation of most of the ilium make standard comparisons difficult. We therefore evaluated the Ar. ramidus innominate by focusing on functionally important features not affected by preservation state. We also manually restored the entire innominate bone, keeping surface distances approximately equal to the original. Upon publication of the 2009 Ar. ramidus Science papers, some questioned the hominid status of the fossils. However, the details of the ilium, such as the short auricular-acetabular distance and prominent anterior inferior iliac spine with its characteristic position and shape are decidedly Australopithecus-like, suggesting that Ar. ramidus was a capable biped. To the contrary, the Ar. ramidus ischium is long and ape-like, in turn indicating retention of substantial climbing　capacities. (Gen Suwa)

References

Lovejoy, C. O., Suwa, G. et al. (2009) The pelvis and femur of Ardipithecus ramidus: the emergence of upright walking. Science 326: 71e1-e6.