Hadean and Archean eons

Hadean and Archean eons - Hadean and Archean eons

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Hadean and Archean eons http://salinella.bio.uottawa.ca/BIO1130/Lectures/default.php? 1130_lect04_Hadn_Sall.php??E?Md2ChapterMcp1 Introduction The earth is about 4500 million years old, multicellular life arose 500 million years ago. - Four main eons: o Phanerozoic (543 Ma to present time) (multicellular organisms) o Proterozoic (2500 – 543 Ma) (Oxygen atmosphere, single celled aerobic organisms) o Archaean (3800-2500 Ma) (mostly anaerobic bacterial life, oxygen accumulates) o Hadean (4600 – 38 00 Ma) (formulation of solar system and planet, ends with origin of life) Eons are made up of Eras! - Phanerozoic o Cenozoic (65 Ma to present time) o Mesozoic (251-65 Ma (Dinosaurs! Wooh! I think) o Paleozoic (543-251 Ma) (at 550 or so, Cambrian explosion) - Hadean Eon o Continuous bombardment creating molten planet, comets help create oceans among other things -> cools planet solidifying the crust o Lightning + volcanic gases created prebiotic soup supplemented by deep sea hydrothermal vents and meteorite materials, leads to simple organic compounds, i.e. carbon o Still can’t be explained, how DNA and RNA first came, nucleotides still can’t be synthesized or how first biopolymers appeared Geological time scale - Early paleontologists couldn’t accurately measure the periods based on sedimentary rock because of lack of technology. - Modern paleontology; radioactive decay, gives much accurate estimations. However is still hard to comprehend because of the magnitude of years; billions Although paleontologists likened to categorizing the periods into different eons, it ignored some contributions that would be happenings overtime within the periods overall; contributions of the archaea and the first unicellular protists to the changes in the planet not being part of the Precambrian period, Biologists saw this error of point of view. - Cambrian explosion (550 Ma); o diversification of animal life in oceans; feeding on protists. o Some life move onto land, than global catastrophe kills off 90% of marine life. - Mesozoic (245-65 Ma) – o many animal life perfect and evolve on land, new species replace marine life, global diversity comes back.
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o As Mesozoic ends, dinosaurs die =( age of reptiles end, another global catastrophe many land animals die - Cenozoic (65 Ma to present) – o often referred to as the age of mammals, however many other species
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This note was uploaded on 09/09/2011 for the course BIO 1130 taught by Professor Fenwick during the Fall '08 term at University of Ottawa.

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Hadean and Archean eons - Hadean and Archean eons

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