Geologic Time Scale Summary

Geologic Time Scale Summary

Precambrian - Cenezoic4.6 Billion Years - Today

Learning TargetsBecome familiar with the Geologic

Time periodsLearn the major events that

happened in each period

Precambrian4.6 billion years ago - about 550

million years ago (formation of Earth)

No life on landFossil bacteria and algaeCrust becomes solid Oxygen in atmosphere

Paleozoic EraAbout 550 mya -

250 myaAge of

invertebrates“Paleo” = ancient,

“zoic” = lifeWarmer

temperatures in North America, Appalachian Mts. form

Cambrian Period550 mya - 490

myaCambrian

explosionFirst great

expansion of sea life

Burgess Shale

Ordovician period490 mya -

440 myaJawless fishFirst land

plantsEnds in mass

extinctionHagfish

Silurian Period440 mya - 408 myaFirst jawed fishInsects like millipedes and centipedes First vascular plants on land

All plants we know today besides algae and fungi

Devonian Period408 mya - 360

myaAge of Fish -->

Fish and land plants become very diverse

First sharks appear

Non-winged insects move to land

Tetrapods move to land near end

Late Mass extinction

Dunkleosteus

Carboniferous Period360 mya - 280 myaCan be split into

Mississippian and Pennsylvanian periods

First insects with wings

First reptilesCockroaches first

appearWide spread Coal

Swamps

Permian Period

280 mya - 248 mya

Age of Amphibians

Continents merge into Pangea

Largest ever extinction ends the Permian

MASS EXTINCTION GRAPH

DINOSAURS!!!

Dimetrodon

Therapsid

Mesozoic Era250 mya - 65 mya“Age of Reptiles” aka “Age of

Dinosaurs”“Meso” = middle “Zoic” = life3 Time periods --> Triassic,

Jurassic, Cretaceous

Triassic Period250 mya - 208 myaFirst dinosaurs,

mammals, and crocodyloforms

Ends with a mass extinction

Extinction allows dinosaurs to fill niches and diversify

Jurassic Period208 mya - 146 myaLots of dinosaurs including

sauropodsFirst flowering plantsPangea breaks apart

Cretaceous Period146 mya - 65 myaDinosaurs rule the

earthFirst crocodiles,

ants, bees, snakesFeathered

dinosaurs appearK/T mass extinction

--> no more dinosaurs or pterosaurs

Sea Monsters of the Mesozoic

Cenozoic Era65 mya - ??????“Age of Mammals”

Could be age of birds, flowering plants or insects

Ceno = new zoic = life2 time periods --> Tertiary and

Quaternary

Tertiary Period65 mya - 1.8 myaMammals abound Primitive primatesHorses, whales, pigs,

deerGrasses commonMegalodon

Quaternary Period1.8 mya - ????Ice AgesLarge mammals

like mammoths, mastadons, sabertooths, giant sloths

First Homo sapiensMr. Wirth was born

Macrauchenia stood at five feet tall, at a length of ten feet