Timeline of evolution


 * For the history of evolutionary biology, see History of evolutionary thought.

This timeline of the evolution of life outlines the major events in the development of life on the planet Earth. For a thorough explanatory context, see the history of Earth, and geologic time scale. The dates given in this article are estimates based on scientific evidence.

In biology, evolution is the process by which populations of organisms acquire and pass on novel traits from generation to generation. Its occurrence over large stretches of time explains the origin of new species and ultimately the vast diversity of the biological world. Contemporary species are related to each other through common descent, products of evolution and speciation over billions of years.

Basic timeline
The basic timeline is a 4.6 billion year old Earth, with (very approximately):
 * 4 billion years of simple cells (prokaryotes),
 * 3 billion years of photosynthesis,
 * 2 billion years of complex cells (eukaryotes),
 * 1 billion years of multicellular life,
 * 600 million years of simple animals,
 * 570 million years of arthropods (ancestors of insects, arachnids and crustaceans)
 * 550 million years of complex animals
 * 500 million years of fish and proto-amphibians,
 * 475 million years of land plants,
 * 400 million years of insects and seeds,
 * 360 million years of amphibians,
 * 300 million years of reptiles,
 * 200 million years of mammals,
 * 150 million years of birds,
 * 130 million years of flowers,
 * 65 million years since the non-avian dinosaurs died out,
 * 200,000 years since humans started looking like they do today.

Detailed timeline

 * Note that Ma means "million years ago".

Hadean eon
3800 Ma and earlier.

Archean eon
3800 Ma - 2500 Ma

Proterozoic eon
2500 Ma - 542 Ma

Phanerozoic eon
542 Ma - present

The Phanerozoic eon, literally the "period of well-displayed life", marks the appearance in the fossil record of abundant, shell-forming and/or trace-making organisms. It is subdivided into three eras, the Paleozoic, Mesozoic and Cenozoic, which are divided by major mass extinctions.

Paleozoic era
542 Ma - 251.0 Ma

Cenozoic era
65.5 Ma - present