Early animal evolution Precambrian *Ediacarian (Vendian) biota *First animals Cambrian explosion...
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Transcript of Early animal evolution Precambrian *Ediacarian (Vendian) biota *First animals Cambrian explosion...
Early animal evolutionEarly animal evolution
• Precambrian
* Ediacarian (Vendian) biota
* First animals
• Cambrian explosion
* First shelled animals
* Evolution of animal diversity
Ediacarian (Vendian) BiotaEdiacarian (Vendian) Biota
First animal fossilsFirst animal fossils• Vendian animals
Dickinsonia – annelid, cnidarian polyp, soft coral?Spriggina – annelid or arthropod?
Nemiana – cnidarian medusa, or protist
Vendian = Edicaran PeriodVendian = Edicaran PeriodBiotaBiota
• ~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?
The The Cambrian Cambrian ExplosionExplosion
• 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
Cambrian BiotaCambrian Biota
Burgess ShaleBurgess Shale
• British Colombia rockies
• Shales are remains of deep water deposit of underwater mudslides
• ~ 515 Mya
Cambrian Explosion- Cambrian Explosion- reasonsreasons
• 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