2Geologic Time ScaleDivides Earth’s 4.6 billion year history into partsOur division of time:Day Hour Minute SecondDivision in Geologic Time Scale:Eon Era Period Epoch
3Extinction Means death of every member of a species Most paleontologists agree on five mass extinction events in Earth’s history, but they do not agree on the cause of those events
4Precambrian EraLasted from 4.6 billion years ago to 543 million years agoFirst signs of life are bacteria in the waterBy end of this era, animals such as jellyfish and worms have appeared
5Paleozoic EraLasted from 543 million years ago to 248 million years agoFirst era we find fossils fromBy the middle of the era, we started to see plants on landBy the end of the era, amphibians and reptiles lived on land and there were many insectsEnded with largest mass extinction in Earth’s history (killed about 90% of species)
6Mesozoic Era Lasted from 248 million years ago to 65 million years ago Known as the Age of the Reptiles because they dominatedDivided into Triassic, Jurassic, and Cretaceous Periods
7Mesozoic Era continued Triassic Period – Mammals appear and the first dinosaurs are appearingJurassic Period – The Age of the Dinosaur begins and birds begin to appear towards the endCretaceous Period – Dinosaurs dominate, T-Rex and Triceratops roam the Earth, but all dinosaurs will have died out by the end.
8Cenozoic Era Lasted from 65 million years ago to the present Known as the Age of MammalsDivided into Tertiary and Quaternary Periods
9Cenozoic Era continued Tertiary Period- Mild climate, it is believed that humanlike creatures began walking upright toward the end of this periodQuaternary Period- climate turns very cold, last ice age ends about 11,000 years ago, and modern civilization begins