Mass Extinction.pptVIP

Summer 2006 Workshop in Biology and Multimedia for High School Teachers Chronology of Mass Extinctions Five major mass extinctions in the history of the planet Timeline for Mass Extinctions Millions of Years Ago Ordovician-Silurian - 435 mya Late Devonian - 370 mya Permian-Triassic - 240 mya End Triassic - 205 mya Cretaceous-Tertiary - 65 mya Organisms Affected by Massive Extinctions Percentage of Species Wiped Out Ordovician-Silurian - 85% Late Devonian - 82% Permian-Triassic - 96% End Triassic - 76% Cretaceous-Tertiary - 76% Major Indirect Causes for Mass Extinctions Continental -Flood Basalt Lava (3 of 5) 2. Abrupt Falls in Sea Levels ( 1 of 5) 3. Asteroid Impact (4 of 5) Diversification and Speciation after Mass Extinctions Surviving Species take over vacant habitats and resources Speciation takes every 100 to 100,000 year10 to 10,000 new species per year Phylogenetic Tree of Life Is there a potential Sixth Major Extinction?Species are becoming extinct at a rate of about 4000/year100/day1species every 15 minutes 2050 50% of all species on the planet will be either endangered or extinct Habitat destruction Global Warming 25% mammalian species 15% bird species * Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College. MASS EXTICTIONDIVERSIFICATION Ordovician-Silurian Late Devonian Permian-Triassic End Triassic Cretaceous-Tertiary /globalchange1/current/lectures/complex_life/complex_life.html Permission to use image granted by E O Wilson, Harvard University 16% Families 47% Genera 76% Species including the dinosaurs 22% Families 52% Genera 76% Species 53% Families 84% Genera 96% Species 22% Families 57% Genera 82% Species 25% Families 50% Genera 85% Species Cretaceous - Tertiary End Triassic Permian - Triassic Late Devonian Ordovician - Silurian /SITE/articles/mac_f2.asp humans evolve, extinctions of large mammals 2 Ma Quaternary radiation of mammals, b