BIOLOGY 1M03 Lecture Notes - Lecture 16: Foramen Magnum, Sahelanthropus, Canine Tooth
15 May 2017
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Document Summary
Parabolic dental arcade, thick molar enamel, reduced canine teeth, large molar relative to other teeth. Ancestral hominins shared some of the features of humans and some features of contemporary chimpanzees. Global cooling was associate with decreased rainfall and seasonality, dry seasons. Ancestors of humans (hominins) moved into grassland habitat. The shift from four to two legs; anatomical changes were required for the shift, especially in the structure of the skull, spine, legs and feet. The foramen magnum, the hole in the skull through which the spinal cord passes is repositioned so that the human skull balances directly on top of the vertebral column. The human spine is s-shaped so weight is directly over the pelvis. The pelvis is extensively reconfigured for an upright posture, with internal organs over it. Legs are no longer to enable long stride length for efficient locomotion and their anatomy altered so the legs are directly under the body.
