Bio; Lecture 12; Animal Evolution

Bio; Lecture 12; Animal Evolution - Principles of Biology 2...

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Principles of Biology 2 BIO U103 1/7/07 Animal Evolution How do we get such diversity? Characteristics of animals o Eukaryotes o Multicellular o Heterotrohs o No cell walls First evidence of animals comes from 700 million years ago (fossil evidence) Data from molecular systematics suggest that animals originated about a billion years ago o There wasn’t much oxygen in the air until 2.7 billion years ago Precambrian Era o Strongest evidence of the appearance of animals found in the last period of the Precambrian era o This was called the Ediacaran period o Ediacara fauna—700 million years ago o Consisted of bacteria, algae, some sponges, and some jellyfish o These are all soft bodied, and do not fossilize, since they decay quickly o Some medusa (jellyfish) fossils have been found Cambrian Explosion (533 million years ago) o Period of intense evolutionary diversification o Species are diversified o Animals become larger in size o During this time, nearly all major body plans are present
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Bio; Lecture 12; Animal Evolution - Principles of Biology 2...

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