Geologic Timescale

Cambrian 570MYA-500MYA

Sep 22, 1926

Trilobites are dominant in the earliest record of marine life

Ordovician 500MYA-435MYA

Sep 22, 1937

Invertebrates are dominant in marine life (starfish, sand dollar, sea urchin, and sea cucumbers). The earliest fish appear and are jawless.

Silurian 435MYA-395MYA

Sep 22, 1944

Earliest terrestrial plants and animals

Devonian 395MYA-345MYA

Sep 22, 1953

Armored fish go extinct. Earliest amphibians and ammonites appear

Carboniferous 345MYA-280MYA

Sep 22, 1964

Abundant sharks and amphibians

Permian 280MYA-225MYA

Sep 22, 1974

Extinction of many types of marine animals including trilobites.

Triassic 225MYA-195MYA

Sep 22, 1979

Earliest dinosaurs, abundant cycads and conifers

Jurassic 195MYA-136MYA

Sep 22, 1989

Earliest birds and mammals abundant dinosaurs and ammonites

Cretaceous 136MYA-65MYA

Sep 22, 2002

Earliest flowering plants, climax of dinosaurs followed by their extinction. Great decline of brachiopods, abundance of bony fish.

Tertiary 65MYA-1.8MYA

Sep 22, 2013

Earliest placental mammals, modern mammals, large running mammals

Quarternary 1.8MYA-Present

Dec 22, 2013

Large carnivores, neanderthals, humans, mastadons