User:Universal Life/History

This page outlines major events known to mankind in the history of the universe, in a chronological order. The terminology and the dates given in this page do not always comply with the most recent or major views in the academic chambers. However major differences are indicated through the references. Usually simpler and less technical terms are preferred to the convenience of the reader. Many dates are rounded unless a definitive proof of the date exists.

The abbreviations and symbols included here are listed as follows:

• BY -- Billion (10⁹) Years
• BYA -- Billion (10⁹) Years Ago
• MY -- Million (10⁶) Years
• MYA -- Million (10⁶) Years Ago
• + -- More than

15		BYA	—     Formation of the universe[1]
13	.5	BYA	—     Formation of first stars
13	.1	BYA	—     Formation of first galaxies
8	+	BYA	—     Beggining of the formation of the sun[2]
8		BYA	—     Dissociation of a gaseous substance from the sun, which will solidify to form the earth[3]
4	.54	BYA	—     Formation; of a solid crust (outmost layer) on earth, of water molecules and of a congenial environment for the formation of life[4]

4.54 BYA till 541 MYA

4	.5	BYA	—     Formation of the moon and Mars from earth
4	.45	BYA	—     First rains and oceans
4	.4	BYA	—     First minerals

Earth's heat flow was nearly as three times higher than today. Tectonic activity was very high and volcanoes would erupt very often. First life forms (bacteria) and first land masses were formed.

4		BYA	—     Formation of the rocks from minerals
3	.9	BYA	—     Heavy meteor showers throughout the solar system, especially impacting the moon and to a lesser degree the earth as well
3	.85	BYA	—     First living organism:Prokaryotes[5]
3	.6	BYA	—     Formation of continents or land masses

Earth "calms down" and becomes more stable, the movement of the continents takes a much slower pace. First eukoryatic and multicellular organisms appear in water. Later algae, mosses, fungi, mollusks, sponges and corals appear. First glaciers are formed.

2	.4	BYA	—     Oxygenation of the atmosphere
2	.33	BYA	—     End of the solidification process of the gaseous substances that were forming the earth[6]
2	.1	BYA	—     First eukaryotes and first multicellular organisms
1	.2	BYA	—     First sexual reproduction
	750	MYA	—     First protozoa
	560	MYA	—     First bilateral symmetry and first fungi

541 MYA till Today

The Palaeozoic is the longest of the Phanerozoic eras, and is subdivided into six geologic periods (from oldest to least old): the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian. It was a time of dramatic geological, climatic, and evolutionary change. The Cambrian Period witnessed the most rapid and widespread diversification of life in Earth's history, known as the Cambrian explosion, in which most modern phyla first appeared. Fish, arthropods, amphibians and reptiles all evolved during the Paleozoic. Life began in the ocean but eventually transitioned onto land, and by the late Paleozoic, it was dominated by various forms of organisms. Great forests of primitive plants covered the continents, many of which formed the coal beds of Europe and eastern North America. Towards the end of the era, large, sophisticated reptiles were dominant and the first modern plants (conifers) appeared. The Palaeozoic Era ended with the largest mass extinction in Earth's history, the Permian–Triassic extinction event.

	541	MYA	—     The Cambrian explosion: The relatively rapid appearance of most major animal phyla - First vertebrates
	450	MYA	—     First land plants, first arthropods and first sharks
	420	MYA	—     First lungs
	419	MYA	—     First insects
	395	MYA	—     First tetrapods and the "Age of Fishes"
	370	MYA	—     First amphibians
	360	MYA	—     First crabs and ferns
	330	MYA	—     First amniota, the forefathers of reptiles, birds and mammalians
	320	MYA	—     First synapsids, the forefathers of mammalians
	315	MYA	—     First reptiles
	305	MYA	—     First amniota, the forefathers of reptiles, birds and mammalians
	300	MYA	—     Formation of Gondwanaland