BIOL 2400 Lecture Notes - Lecture 3: Trepassey, Bilateria, Uranium-238
25 Dec 2014
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1: perimineralized, casts and molds, exceptional preservation (includes soft parts but rare) impression. Gradual vs. punctuated evolution (superposition) gradual like horse, ancestral species slowly gets legs hypothesis 1 above : jumps/punctuated because of large change in morphology in next strata. Oldest known rocks 4 billion years near great slave lake, canada no fossils! Dating ancient rock radiometric dating indicates that the earth is 4. 6 billion years old. Different minerals have different proportions of rubidium. The only place new strontium 87 is from radioactive decay of rubidium. Ratio increases over time, but increases faster in rocks that started out with more rubidium. 1. 8 billion year old fossils near great slave lake, canada can slice into these and see the structures (like mats, outside is alive, dies and reforms, grows) Eukaryotic multicellular life earliest fossils of algae: red algae, bangiomorpha (1. 2 bya) on the basis of diagnostic cell division patterns sexual reproduction.
