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Early animal evolution

Early animal evolution. Precambrian Ediacarian (Vendian) biota First animals Cambrian explosion First shelled animals Evolution of animal diversity. Ediacarian (Vendian) Biota. First animal fossils. Vendian animals. Nemiana – cnidarian medusa, or protist.

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Early animal evolution

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  1. Early animal evolution • Precambrian • Ediacarian (Vendian) biota • First animals • Cambrian explosion • First shelled animals • Evolution of animal diversity

  2. Ediacarian (Vendian) Biota

  3. First animal fossils • Vendian animals Nemiana – cnidarian medusa, or protist Dickinsonia – annelid, cnidarian polyp, soft coral? Spriggina – annelid or arthropod?

  4. Vendian = Edicaran PeriodBiota • ~610 to 540 Mya • SE Australia, Northern Europe, elsewhere • Shell-less • Modern groups (cnidarians, sponges, annelids?) • Some organisms in completely different phyla • Vendian/Cambrian extinction – due to glaciation?

  5. The Cambrian Explosion • Hard skeletal parts (shells of calcium carbonate & exoskeletons of chitin) • Post 570-510 Mya • 54 out of 55 classes w/ skeletons today, appeared • Burgess Shale

  6. Cambrian Biota

  7. Burgess Shale British Colombia rockies Shales are remains of deep water deposit of underwater mudslides ~ 515 Mya

  8. Cambrian Explosion- reasons • Edicaran biota go extinct → empty habitats? • Higher oxygen levels? • Changes in seawater chemistry? • Continental configuration → climate changes, ocean circulation • Glaciation or deglaciation → sea level change • Extra-terrestrial cause

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