ANTH 1001 Lecture Notes - Lecture 10: Orrorin, Foramen Magnum, Tugen Hills
Document Summary
Primitive (chimp or gorilla like: very large, thick brow ridge, chimp-like cranial capacity (320-380cc) Found first in "92 by white et al. Two species: a. kadabba: 5. 2-5. 8 ma, a. ramidus: 3. 9-4. 4 ma. Habitat reconstructed as mostly wooded with a higher water budget than today supporting a rich flora and fauna. A. ramidus cranial morphology: cranial capacity 300-350 cc, midfacial projection but reduced sub nasal prognathism, foramen magnum placed beneath the cranium, no canine honing facets, reduced canine, reduced sexual dimorphism. A. ramidus postcranial morphology: short and broad pelvis, abductable big toes but use as a stabilizer in bipedal locomotion, primitive foot with some bipedal features. Intermebral index close to 1. 0: no suspensory or knuckle-walking adaptations. Orthograde posture of arboreal feeding is a pre-adaptation for bipedalism. Bipedalism removed selection against brain size increase: arboreal life (needing to hang on immediately after birth) requires babies to be precocial. Terminal adaptation and feedback loops: action effect feedback.
