BIOLOGY 1M03 Lecture Notes - Lecture 9: Nitrogen Fixation, Ecosystem Diversity, Background Extinction Rate
11 Aug 2018
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8:31 am: actual divergence times predate the oldest fossil, time of extinction postdate newest fossil. Sexual dimorphism decreased, brain size increased, body size increased, juvenile period increased, longer learning period. Actual divergence times probably pre-date the oldest fossil: time of extinction probably post-date the newest fossil. The pleistocene epoch started 1. 8 mya and involved a cooling trend that started in the miocene. ~6 mya: not only the amount of change but the rate of change, changes between interglacial and glacial there are changes in the ecosystems. Upper pleistocene is from 130,000 12,000 years ago and ended with warm interglacial phase. Homo ergaster: h. ergaster lived from ~1. 8 0. 6 mya in africa and eurasia, possibly not the same species as h. erectus which was first found in indonesia. Ancestral features include narrowing of braincase behind the eyes, receding forehead. Derived features include shorter nose, less prognathic face, taller skull, smaller jaw and molars, occipital torus, less sexual dimorphism, large brain.
