GEOL 105 Lecture Notes - Lecture 26: Foramen Magnum, Brain Size, Bipedalism
23 Apr 2020
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Document Summary
Climate change cooling, drying, and wider climate fluctuations. Climate overall drying but each rift valley might be slightly different and each glacial and interglacial changed the microclimates. Strong effect of mountain building and plate motion on climate. Plate position and barriers to migration help define which animals live where. Rift valleys easier to find fossils dry, lots of cliffs (so lots of erosion) you don"t have to dig as far. Lots of erosion also means the bones get buried and preserved. The rifts are not all equally wet (lakes) Chimps and hominids branched from a common. Bipedalism benefits ancestor around 6 & 8 million years ago. Close to the common ancestor of humans and chimpanzees. Brain size 360-370 cc (slightly smaller than a male chimp"s) Sahelanthropus is intermediate between ape and human, but it is closer to humans. It has a more of an upright stance.
