Animals 1 - ANIMALS When did animals evolve The"Cambrian...

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1 ANIMALS Fig. 28.4 You are here… When did animals evolve? • The “Cambrian Explosion” – ~ 550 million years ago – Burgess shales – Chinese fossil beds • The Edicaria Hills of Australia – Precambrian fossil animals ~ 600 million years ago? • So… the first animal may have “roamed” the seas nearly 1 billion years ago Ca. 550 mya
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2 The Burgess Shale formation Western Canada Pteridinium A Vendian fossil that may be a member of a phylum level group, now extinct. Tribrachidium heraldicum Vendian animal from the Ediacara Hills of Australia. Affinities to modern phyla unclear. No, this is not the face of an alien that appeared in some woman in Idaho’s toast! Spriggina Vendian animal from Australia. May be related to Arthropods?
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3 Ogygiopsis, a trilobite Vauxia gracilenta, a sponge from Burgess Shale deposits “Why” did animals evolve? • Ecological causes – Esp. predator-prey relationships • Geological causes – Enough oxygen in the atmosphere • Genetic causes
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This note was uploaded on 04/24/2008 for the course BIOL 103 taught by Professor Foster during the Fall '08 term at Clark University.

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Animals 1 - ANIMALS When did animals evolve The"Cambrian...

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