BIOL 2400 Lecture 4: lec 4
25 Dec 2017
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Document Summary
H1: extraterrestrial origin of life theory (aa found) Murchison meteorite from australia 1969 -found aa inside the meteorite. Living stromalites in rocks near shark bay, western australia. Outer core living and inner part dead, made of layers of bacteria. Fossil stromalite: mats of filamentous cyanobacteria (blue-green algae) 2 bya (billion years ago) Living cyanobacteria (cid:498)extant(cid:499), not all species form mats! Archaea closer to eukaryote than bacteria: earlier eukarya fossils: ~ 1. 8 bya, earliest bacteria fossils: potentially 3. 45 bya; abundant by ~ 2. 6 bya, stromatolites correspond to rise in oxygen, earliest archaea fossils: ~ 3. 5 bya. Potential biochemical signs of life date to 3. 7 bya but claim is controversial. Earliest accepted stromalite fossils of mats of filamentous bacteria (cyanobacteria) date to 3. 4 bya. Life present on earth only about 1 billion years after our plants formation! Bacteria still constitute most of the earths biodiversity.
