ESS261H1 Lecture Notes - Lecture 10: Basalt, Paleozoic, Blastoid
Document Summary
In the fossil record, we can recognize a mass extinction event w/ sharp boundaries but this is not to be confused with erosion or other reasons fossils weren"t preserved (incomplete sedimentary record) Earth has experienced 5 mass extinctions: cretaceous-tertiary (k-t): intermediate = 30% of families, 50% of species, end triassic: intermediate, end permian (p-tr): major = 50% of families, 90% of species biggest yet, late devonian: intermediate, end ordovician: intermediate. Evolution of cephalopods (earliest cambrian lagerstatten: sepkoski"s 3 faunas. Jack spekoski is an american paleontologist that has contributed to the knowledge of mass extinctions. He explains three great evolutionary faunas in the marine animal fossil record: Almost no large animals, w/ very few predators = short food chains. Paleozoic fauna: brachiopods, stony and lacy bryozoans, stromatoporoids, cephalopods, crinoids and blastoids, starfish, graptolites. Modern fauna: bivalves, gastropods, vertebrates, echinoids, crustaceans, gymnolaemate bryozoans, reptiles. Volcanic eruption: mass extinction and the geologic rock record.
