Geologic Time Scale Geologic Time Scale Summary of

Geologic Time Scale • Geologic Time Scale • Summary of major events in Earth’s past, preserved in the rock record

Division of Time • Eon • Era • Period • Epoch • Largest division of time; divided into eras • 2 nd largest – divided into periods • 3 rd largest – divided into epochs

• Evolution • Natural Selection • The process of change that produces new, changing or evolving life forms • “survival of the fittest”

• Precambrian Time • stromatolites • No life on land • Simple marine fungi and algae only • Lots of volcanic activity • Original atmosphere came from volcanoes • Fossils of layers of cyanobacteria & trapped sediments

• Paleozoic Era • Had 7 periods • Cambrian - Trilobites • • • Age of Invertebrates • Crablike fossils prevalent Ordivician – Graptolite • Prevalent fossil of colonized organisms • “sea scorpion” Silurian-Eurypterids • lungfish Devonian • Sea lilies & one-celled Carboniferous – Crinoids & Foramnifera calcite-shelled organisms • DRY climate Permian

• Mesozoic Era • 3 periods – Triassic, Jurassic and Cretaceous • Triassic • Jurassic • Cretaceous • Age of Reptiles • Ammonites(cephalop ods) & Reptiles • First dinosaurs • Dinosaurs dominant & Mammals begin to thrive

• Cenozoic Era • Age of Mammals • 3 periods – Paleogene, Neogene and Quaternary • Quaternary was the rise of hominids and humans

• Hominid • Bipedal • 1 st hominid found was Lucy • Australopithicus, Homo habilis, Homo erectus, Homo Sapiens, Homo sapien • General name for modern humans • Walked on 2 legs • Lucy was an Australopithicus skelton