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Unformatted text preview: Earth 2 Tuesday, March 16th, 1999 Announcements: Thursday's test is postponed until next Tuesday! Lecture notes: ABRUPT CHANGES AFFECTING THE EARTH Extinction Time periods in which a significant organism never crosses earth again Look at the distributions of families of organisms--2-4 families of organisms become extinct during significant periods of geologic time The Revolutionary Clock changed at 240 million years...Ancient life, Middle Life, and Modern Life 250 million years ago, 200 families of organisms became extinct each time period K-T Boundary Came into existence 65 million years ago Known as the Cretaceous-Tertiary Boundary (K-T Boundary) Organisms that became extinct: plankton autotrophs follow down the food chain "benthos"--bottom dwelling organisms became extinct in coastal areas benthos exception: detritus feeders large land animals over 25 kg died large land animal exception: trees survived This extinction occurred faster than it can be resolved. Sediments are mixed by This extinction occurred faster than it can be resolved....
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This note was uploaded on 02/21/2008 for the course EARTH 002 taught by Professor Eigenbrode during the Spring '99 term at Pennsylvania State University, University Park.
- Spring '99