ANTHRO 101 Lecture Notes - Lecture 18: East Los Angeles College, Orrorin, Sahelanthropus
Document Summary
Diversity of fossil apes started declining 9 mya. Dryer and cooler climate in late miocene resulted in poor fossil record of apes from africa. Likely spent more time in trees still retained many arboreal adaptations. Bipedalism, thicker enamel, and reduced canines are the first derived features. Do not know enough to support bipedalism. Chad, 2002 7-6 mya argued to be predecessor of chimps, rather than early hominins. Primitive 350cc brain size (chimp-like), large brow ridges. Derived flat face, thick enamel, small canine. Bipedal location of foramen magnum and placement of neck muscle attachment (much higher in nhp) Derived small teeth with thick enamel. Bipedal femoral neck length and shape (very angled) Primitive upper canine hones against lower premolar, canines are not reduced. Derived toe bone similar to toe bones of later hominins (might be bipedal) Primitive opposable big toe, long fingers with short thumbs, thin enamel on molars, small brain.
