Geological Time Scale Eras

• C - Cambrian (541–485 Ma):

Rapid diversification of life, known as the "Cambrian Explosion".

O - Ordovician (485–444 Ma):

Marine invertebrates diversified; early vertebrates appeared.

S - Silurian (444–419 Ma):

First vascular plants and colonization of land by arthropods.

D - Devonian (419–359 Ma):

"Age of Fish"; first tetrapods appeared.

C - Carboniferous (359–299 Ma):

Widespread coal swamps; first reptiles.

P - Permian (299–252 Ma):

Formation of Pangaea; ended with the largest mass extinction in history.

Tr - Triassic (252–201 Ma):

• First dinosaurs and mammals appear.

J - Jurassic (201–145 Ma):

Golden age of dinosaurs; first birds appear.

K - Cretaceous (145–66 Ma):

Peak of dinosaur diversity; first flowering plants; ended with the asteroid impact.

Pg - Paleogene (66–23 Ma):

Rapid evolution of mammals following the extinction of dinosaurs.

Ng - Neogene (23–2.6 Ma):

• Modern mammals and birds evolve; early hominids appear.

Q - Quaternary (2.6 Ma–Present):

Ice ages, megafauna extinction, and rise of modern humans.

Ediacaran (635 myo)

Animal fossils

Cyrogenian

• Inferred animal lineages

• Earliest Eukaryotes