Mass Extinctions Throughout History.pptx

Mass Extinctions What’s a mass extinction? ● a sharp decrease in the number of species (>50%) in a relatively short period of time (geologically speaking, anyway). ● There are different ways a mass extinction can occur, including… ●Asteroids ●Comets ●Global warming ●Ice age ●Supervolcanoes ●And mo...

Mass Extinctions What’s a mass extinction? ● a sharp decrease in the number of species (>50%) in a relatively short period of time (geologically speaking, anyway). ● There are different ways a mass extinction can occur, including… ●Asteroids ●Comets ●Global warming ●Ice age ●Supervolcanoes ●And more… How many mass extinctions have there been? The Ordovician-Silurian Extinction ●439 million years ago ●Rapid glaciation/deglaciation ●Sea level changes ●Killed about 25% of marine families ●Killed 60% of marine genera Late Devonian Extinction ● About 364 million years ago ●Asteroid impact ● About 22% of marine families were killed ● About 57% of the genera were killed The Great Permian Extinction, aka The Great Dying ● Volcanic eruption, asteroid impact, or supernova ● Informally called “The Great Dying” ●Most severe extinction in Earth’s history ●96% of all marine species were killed ●70% of terrestrial vertebrate were killed ● Occurred approximately 250 million years ago ● Took a few million years to happen, and 6 million years to recover 2021 Update on The Great Dying (watch the End Triassic Extinction ● 199 million to 214 million years ago ● Massive floods, lava eruption, opening of Atlantic Ocean basin ● Lead to deadly global warming ● 22% of Marine families ● Vertebrate deaths unknown Cretaceous-Tertiary Extinction ● Uncertain events → rapid rate ● Asteroid in Mexico ● 200 Kilometers across making the asteroid itself about 9 miles wide ● Caused: ● forest fires ● ignited volcanic ● tidal waves ● severe storms ● NO SUNLIGHT! ● Climate change ● Tropical period for plants and animals ● Drastic temperature change ● Trophic cascade ● Volcanic eruptions ● Clouds of dust, sulfuric acid, and poisonous gas ● Toxic air ● Block sunlight ● Climate change A 6th Mass Extinction? ● Holocene Extinction ● Human era ● Birds, mammals, reptiles, amphibians ● Homo sapiens dispersal from Africa → hunting and gathering ● Estimated 500,000 – 1,000,000 species have become extinct ● Hunting ● Population ● pollution ● climate change Want to learn more? 6th Mass Extinction - documentary (50 min) Mass Extinctions in History - The Sci Show (10 min) Top 10 Animals That Recently Went Extinct - (10 min)