BIOL 2400 Lecture 4: Lec 4-Palaeontology I
25 Dec 2017
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Document Summary
Nature of fossil record (mostly hard parts) Dating the fossil record with radioactive decay. Early unicellular life soon after earth formed. Early multicellular eukaryotic life 2-4 bya (life formed after a very long time) Large complex animals (lagerstatten= soft parts: ediacaran fauna 575 mya (precambrian period, chenjiang fauna 515 mya (cambrian period, burgess shale fauna 505 mya (cambrian period) Sedimentary rocks form layers from the deposition of small particles in basins along continental shelves and contain fossils: ex: limestone"s, sandstones, shale"s, lava and volcano igneous rock, don"t look for fossils there. Biomarkers: is molecular evidence of life in the fossil record, biomarkers can include fragments of dna, molecules such as lipids, or specific isotopic ratios. Sites with an abundant supply of exceptionally well-preserved fossils-often including soft tissues-from the same period of time. The fossilized animals were swept into anoxic (low oxygen) pools, lagoons or bays where bacteria and other scavengers could not destroy the animals body.
