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Unformatted text preview: O NOT have to memorize for Prof. True’s part of the course Gradual change in the fossil record (in posterior) hlp://www.zoology.ubc.ca/~bio336/Bio336/Lectures/Lecture23/Trilobites.jpg Macroevolu9onary palerns: Mass ex9nc9ons Permian‐Triassic ex9nc9on ~ 96% of all marine species ~70% of all land species Meteor impact in Yucatan ‐ ex9nc9on of dinosaurs Causes of mass ex9nc9ons • S9ll largely unknown • 65 mya Cretaceous‐Ter9ary – much debated currently – Meteor impact – But also major volcanic ac9vity in Asia/India • Sea level drops/rises o^en implicated • Atmospheric changes (see ﬁg 21.5 in book) • Climate change (see ﬁg 21.6 in book) – e.g. “Flood Basalt events” • Major volcanic episodes on land masses or ocean ﬂoors • Send large amounts of par9culates into atmosphere for extended periods • Can cause major ex9nc9ons of plants and collapses of food chains ConAnental DriI...
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- Spring '08