LECTURE 20

Apuntes

LECTURE 20: HISTORY OF LIFE & HUMAN EVOLUTION QUIZ 8 – Wednesday ▪ O2 levels increase again ▪ Clean slate opens room for new diversity (largest animals ever on earth emerge – dinosaurs) ▪ Continents again drift into northern –southern groups ▪ Generally warm and humid time 3. The age of the dinosaurs - Mesozoic 4. The Cretaceous Extinction – Ends Mesozoic 5. The Age of Mammals – Cenozoic ▪ Catastrophic event (likely meteor strike), new cooling trend 4. The Cretaceous Extinction – Ends Mesozoic ▪ Catastrophic event (likely meteor strike), new cooling trend ▪ most animals above 55 lbs can not be sustained, ~76% of all species extinct ▪ dinosaur extinction (except birds) ▪ Opens the beginning of the Cenozoic 4. The Cretaceous Extinction – Ends Mesozoic ▪ Mass extinctions End of Cretaceous (65.5 mya) ▪ Collision caused tsunamis, giant plume of debris, massive forest fires ▪ Blocked the sun, prevented photosynthesis ▪ Many fossil species found in Cretaceous rocks are not found in overlaying Tertiary rocks ▪ High iridium concentration between Cretaceous and Cenozoic layer strong evidence of meteor impact 4. The Cretaceous Extinction – Ends Mesozoic 5. The Age of Mammals – Cenozoic ▪ Begi...