Geologic Time Scale Major Events Target 7

Precambrian Time

Cambrian Explosion of LIFE Anomalocans-top predator

Mass Extinction #1: End Ordovician 60% extinct global climate change caused by glaciation (due to Gondwana forming near south pole)

Mass Extinction #2: End Devonian ● 70% extinct ● same glaciation; North America and Europe on Equator, the rest in the Southern Hemisphere 30 foot predator Dunkleosteus (one of the biggest armoured fish)

Mass Extinction #3: End Permian ● 96% extinct (all life today descended from the 4% that remained) ● The only mass extinction to affect insects ● Temperature causes 10 foot predator Dinogorgon

Mass Extinction #4: End Triassic ● 53% extinct ● large outpourings for lava from Pangaea break up mammal-like reptiles such as Thrinaxodon thrived in the Triassic until its demise

Mass Extinction #5: KT Extinction (End Cretaceous) ● 50% extinct (all animals over 55lbs went extinct -no large animals from the land, air or sea survived) ● lava erupted in India and meteor/asteroid collided in Mexico

Are we in a 6th mass extinction? ● humans have driven a 1,000 species to extinction in our 200,000 years on Earth ● since 1500 we have killed off 322 types of animals including passenger pigeons, Tasmanian tigers, and baiji (a freshwater dolphin) ● 20,000 are currently threatened ●⅓ of all species are threatened or endangered ● bees…. ● should we step in? largest carnivorous marsupial