Geological Eras


Geological Time Chart

(Evolution of major groups of animals)

Era

Period

Epoch

Million

Years

Organisms evolved

Coenozoic

Quaternary

Holocene

0.01-0

Dominance of man. Domestication of animals and agriculture. Modern genera and species evolved. Last ice age 30-40 thousand years ago. Woolly mammoth extinct.

Pleistocene

1.5-0.1

Mass extinction. Huge floods. Ice age. Many large mammals extinct. Mastodons and woolly mammoth extinct. Prehistoric man evolved. Cave paintings.

Tertiary

Pliocene

6-1.5

Dry climate. Oceans shrink. Mammals increase specialization. Mountains rise. First hominids appear. First orchids.

Miocene

 23-6

Ice age. First man-like apes. Evolution of apes, monkeys, horse, elephant. Radiation of grazing mammals. Huge grasslands. All grass subfamilies distinct.

Oligocene

 37-23

Archaic mammals attain their maximum diversity. Creodonts (archaic carnivores) appear. First apes. Origin of grasslands.

Eocene

53-37

Forests of monocotyledons and flowering plants appear. Ancestors of horse, camel, elephant appear. First bats.

Paleocene

 65-53

Climate warm. Vegetation abounds. Ancestors of most modern mammals appear. Insectivores abundant. First grasses, Rhododendrons, whales and rodents.

Mesozoic

Cretaceous

 

135-65

Mass extinction. 60% of tetrapod families extinct. Himalayas, Andes, Alps arise. Dinosaurs and Ammonites extinct. First monocotyledons. First marsupials and placental mammals (Pantotheres). First flowering plants. Climate cool. Angiosperms radiate.

Jurassic

 

205-135

First bird, Archaeopteryx. Dominance of dinosaurs. Earliest mammals. Dicotyledons and conifers common. Continents become high. Origin of insect pollinators.

Triassic

 

250-205

Massextinction. 80% of tetrapod families extinct. Continental drift begins. Arid conditions. Gymnosperms dominate. First dinosaurs.Mammal-like reptiles. First teleosts, first crocodiles and first flying reptiles.

Palaeozoic

Permian

 

 290-250

Mass extinction. 70% of tetrapod families extinct. Single land mass, Pangaea and single ocean. Continents rise. Glaciations set in. Expansion of reptiles, origin of Cotylosauria and Therapsida. Last trilobites.

Carbonife-

rous

Pennsylva-

nian

290

Warm and humid climate. Swamps abundant. First modern soils. First reptiles. Sharks abundant. First mammal-like reptiles. Earthworms.

Mississipp-

ian

350

Forests of ferns and gymnosperms. Foraminiferans and shell-crushing sharks abound. First winged insects. Radiation of amphibians. Little seasonal variations.

Devonian

 

410-350

Mass extinction. Arid climate. First gymnosperm forests. First amphibians (Labyrinthodonts). First spiders. Dominance of fishes. First ferns. First vascular plants. First insects.

Silurian

 

440-410

Algae dominate. Land plants definite. Trilobites decline. First scorpions and millipedes appear. First fishes, ostracoderms and placoderms appear.

Ordovician

 

510-438

Land submerged. Warm climate. Algae abound. Plants invade land. First corals. First vertebrates. Cephalopods and snails. First Agnatha.

 

Cambrian

 

600-510

Mass extinction. Mild climate. Marine algae. Many invertebrates. Trilobites. Brachiopods. Sponges. Molluscs. Explosion after mass extinction.

Proterozoic

   

3,500-600

Primitive aquatic algae and fungi. Annelid burrows. Protozoa. Oxygenation of atmosphere. Prokaryote radiation. Skeleton of sponges.

Archeozoic

   

4,600-3,500

Calcareous deposits by algae. Origin of life. Fossils of cyanobacteria.

Solar

   

5,000-4,600

Formation of Solar system. Strong solar wind. Formation of primitive atmosphere on earth.

Cosmic

   

20,000-5,000

Big Bang and matter synthesis.