A short blurb on Ar. Ramidus...

    Ardipithecus ramidus or Ar. ramidus is a early hominid associated with the Middle Awash region and Gona, Ethiopia. It is believed to have lived rougly 4.4 ma. Today, I will be covering the skull as talked about by Gen Suwa and others in the paper "The Ardipithecus ramidus Skull and its Implications for Hominid Origins." The Ar. ramidus skull from Aramis, Ethiopia (part of the ARA-VP- 6/500 skeleton) is highlighted because it predates Australopithecus and therefore, is able to help tell us about early hominid skulls, brains, and faces. 

                                                          

    Ar. ramidus has an overall 'small' face that lacks the "large cheeks of heavy chewing Australopithecus," with a 300-350cm³ brain. There is mid facial projection like Sahelanthropus, though the lower face does not project as much as in chimpanzees. Ar. ramidus was probably omnivorous and fed both in the trees and on the ground. There is little differences between the canines of males and females, showing small sexual dimorphism (and possibly less aggression), opposed to that of chimpanzees. Ar. ramidus has a short cranial base with the rear of the skull down turned, similar to that of Sahelanthropus, which is associated as a hominid feature. "The steep orientation of the bone on which the brain stem rests" suggests "advanced" cranial base flexion. This flexion has recently been associated with "neural reorganization" (early hominid brain evolution) vs. the generally accepted association with bipedal walking. All of this is to say, Ar. ramidus shared characteristics with the genus homo and chimpazees and can help shed light on the early evolution of homo. 

Suwa, G., et al. “The Ardipithecus Ramidus Skull and Its Implications for Hominid Origins.” Science, vol. 326, no. 5949, 2009, doi:10.1126/science.1175825.