Geologic Time Scale

Eon Eras Periods Epochs Age (beginning) notes
Phanerozoic Cenozoic Quaternary Holocene (Recent) 10000 BP End of Ice Age
Pleistocene 1.8 Ma
Tertiary Pliocene 5 Ma
Miocene 24 Ma
Oligocene 34 Ma
Eocene 55 Ma
Palaeocene 65 Ma Mass extinction: dinosaurs, pterosaurs, and ammonites extinct
Mesozoic Cretaceous 141 Ma Angiosperm plants, Mesozoic reptiles peak
Jurassic 205 Ma Ferns, cycads, ginkgos, ammonites
Triassic 215 Ma Molluscs and reptiles dominant, dinosaurs, ichthyosaurs
Palaezoic Permian 298 Ma Trilobites extinct, Amphibians and reptiles dominant land animals
Carboniferous 354 Ma Foraminiferans, corals, bryozoans, brachiopods, amphibians become more common
Devonian 410 Ma Corals, brachiopods, ammonoids, crinoids, fishes and early land plants
Silurian 434 Ma primitive fish
Ordovician 490 Ma Graptolites dominant, also trilobites, brachiopods, bryozoans, gastropods, bivalves, echinoids, crinoids,
Cambrian 545 Ma Marine animals with mineralized shells appear: trilobites, echinoderms, brachiopods, molluscs, primitive graptolites, a variety of worms
Proterozoic Precambrian Vendian ~2500 Ma 1st multi-celled organisms
Archean ~4000 Ma The evolution of life, 1st one-celled organisms
Priscoan ~4600 Ma The formation of the Earth’s crust, Approx age of oldest rocks 3,800 Ma
Note: Ma=million years