Lecture 5

Lecture 5 - Lecture 5 6-16-09 Phylogenies and Other topics...

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Lecture 5 6-16-09 Phylogenies and Other topics in evolution Outline: History of life Systematics and Phylogeny Paleozic: cambrian periodn 542-488 ma -cambrian explosion= great radiation -most phyla of animals appear, some we can assign to current -evolution of hard shells skeletons rich fossible deposits, burgess shale Cambrain- many major clades first appear annelid chordate arthropod = diversivication in ecology precambrian animals- sessile filter feeder and predatore of planktan after- all major marine feeding types, got closer to moder life we see today Cambrain period ended with a mass extinction lost many trilobites Mass extinictions time interval with a widespread highly elevated rate of extinction vs. backgroud extinctions that are constantly occuring 5-7 mass extinc causes sometimes known and each followed by new character Ordovician period 488-444 ma move to land algal ancestor of plants required adapt to avoid dehydration -multicellular, protected embryos -waxy cuticle, very small and long to the ground,found sunlight without water in way *major transition in the history of life on earth ended with a mass ext, 2nd largest Silurian Period 444-416 ma
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Lecture 5 - Lecture 5 6-16-09 Phylogenies and Other topics...

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