User:Orosas/Ardi

Pelvis
Although Ardi (and the rest of the Ardipithecus ramidus’ species) had more ancestral hands, feet, and limbs, Ardi’s pelvis told a different story. The parts of Ardi’s pelvis that were recovered include her left hip, her right ilium, and a fragment of her distal sacrum. A shorter ilium and a curve in the lower spine were the characteristics gathered from these partial remains that indicate Ardi, and the Ardipithecus ramidus species, had the ability to walk upright. The shift to bipedality is only beginning to emerge in Ardi because there are characteristics in Ardi’s pelvis that are both found in all later hominids and characteristics that are found in extant African apes. A characteristic that is found in Ardi and in all later hominids is a separate growth site for the anterior inferior iliac spine. A similar ischial structure is a characteristic found in Ardi and in extant African apes. This mixture of characteristics indicates Ardi’s bipedality was an earlier version of bipedalism compared to later hominids like Lucy. Regardless of how ancestral Ardi’s bipedality was, these characteristics found in Ardi’s pelvis show bipedalism was well underway by 4.4 million years ago, even with the ability for arboreal locomotion still present in the hands and limbs.

Foot
Ardi’s foot is a special area of interest when examining the evolution of bipedalism in early Hominids, and the bipedality of Ardipithecus ramidus, because all five toes do not line up. The remains of the foot from Ardi and other Ardipithecus ramidus specimens that can be studied includes “a talus, medial and intermediate cuneiforms, cuboid, first, second, third, and fifth metatarsals, and several phalanges. ” The foot of Ardi contains an opposable hallux (big toe) that is similar to chimpanzees. This opposable hallux is believed to have been used to aid in tree climbing. On the outside, Ardi’s foot may look like it belongs with other Apes, but on the inside, Ardi’s foot contains a bone called the os peroneum, which allows the bottom of the foot to be more rigid. The rigidity of the bottom of the foot was believed to allow Ardi to walk upright, and the other four toes that were aligned performed the “toe off” action during a bipedal motion. The combination of features found in Ardi’s and other Ardipithecus ramidus foot bones captures a moment in time where these primitive primates were beginning to leave the trees and spending longer periods of time on the ground.