BIOLOGY 1101 Lecture Notes - Lecture 23: Carboniferous, Cenozoic, Labyrinthodontia
6 Sep 2016
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Document Summary
Evidence: iron oxide in rocks could only form in the presence of atmospheric oxygen. O2 levels rose over several hundred million years. Significance: atmospheric oxygen essential for cellular respiration, which allows organisms to collect energy from organic molecules. Period from earths formation to approximate time of emergence of life (which coincided with increased stability on earth) No life, at least until the end of this period. Most rock was lava/magma-based (sedimentary rocks hadn"t had an opportunity to form yet) Confirmed life at this time; is unicellular, prokaryotic. Cyanobacteria (blue-green algae) evolves during this period. Photosynthesis causes the oxygenation of the earth. Several periods of global glaciation in this eion. When: 1. 2 bya, complex multicellularity by 600 mya. Evidence: numerous fossils, genetic evidence suggests divergence of modern eukaryotes occurred about 1. 5 bya. Significance: can overcome size limitations associated with diffusion, allows for differentiation and specialization. You and a friend are both arrested and put into solitary confinement for interrogation.
