Geologic Time Scale

Hadean eon

solar nebula

Hadean

formation of earth & moon, heavy bombardment

Archean

first form life (prokaryotes)

archaean

formation of earth’s crust

proterozoic

start of plate tectonics

proterozoic

oxygenation, first eukaryotes

phanerozoic

current eon

paleozoic era

break-up of supercontinent

formation of plants

cambrian period

evolution of arthropods (ancestor of insects & crustaceans)

chordates (animals with spinal cords)

Ordovician

abundance of marine invertebrates

ordovician

trilobites (famous arthropods)

ordovician

first land plants

silurian period

spread of jawless fish

mollusks and corals thrived

silurian period

first acceptable evidence of terrestrial life (vascular plants)

devonian period

age of fishes

devonian period

first appearance of sharks & lobe-finned fish

devonian period

emergence of tetrapods (first land vertebrates)

first amphinians

carboniferous period

tetrapods began laying eggs on land

carboniferous period

first reptiles

permian period

permian extinction (largest mass extinction)

permian period

coral reefs flourished

pangaea forms

mesozoic

age of reptiles

age of dinosaurs

triassic

rise of reptiles

first dinosaurs

jurassic

first birds

age of dinosaurs

cretaceous

iconic dinos: triceratrops & ptesaur

flowering plants

mass extinction

cenozoic

age of mammals

paleogene period

mammals diversify

epochs:

1. paleocene - first major division of rocks

2. eocene

3. oligocene

neogene

first hominins

epochs:

1. miocene

2. pliocene

neogene

rise to early primates, early humans

bovids, cattle, sheep, goat, antelope, gazelle

quaternary

ice age

rise of humans

epochs:

1. pleistocene

2. holoceme