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Precambrian Period
The precambrian period started around 4.6 billion years ago and ended approximately 542 million years ago -
Devonian Period
http://www.ucmp.berkeley.edu/devonian/devonian.phpThis period brought with it the diversification of life in the seas as well as life on land. In terms of the oceans, the brachiopods became the "rulers" of the seas, as well as the first tetrapods being introduced. In terms of land animals and plants there was also a big change. In terms of plants they began to grow. They were rootless and leafless plants. For animals the tetrapods began to diversify and the first arthropods were introduced -
Paleozoic era
The Paleozoic period started at the end of the Precambrian Period and ended 251 million years ago. This era consists of 6 periods -
Cambrian Period
http://www.ucmp.berkeley.edu/cambrian/cambrian.phpThe Cambrian period was the period in which life on earth first started. This was the point in time where many organisms who were living had hard shell. They all lived in water. -
Ordovician Period
http://www.ucmp.berkeley.edu/ordovician/ordovician.phpThe Ordovician Period brought with it the life of newer species such as many brachiopods (snails, clams) and some forms of coral and more diverse aquatic plants. Also some species of fish were introduced into the waters. -
Silurian Period
http://www.ucmp.berkeley.edu/silurian/silurian.phpThe Silurian period brought with it many different evolutions to the underwater life. The introduction of jawed-fish and freshwater fish occured in this time period. It is said that fossils show that plants and animals first moved to land in this period as well. -
Carboniferous Period
http://www.ucmp.berkeley.edu/carboniferous/carboniferous.phpIn this period trilobites grew scarce. The climate became more humid. The heavily armoured fish began to resemble presnt day fish. Lycopods went into extinction. Many insects came into being such as scorpions and dragon flies. As well as land snails. Tetrapods began to diversify creating predators with longer snouts (alligators). Also the reptiles and amphibians of this period began laying eggs -
Permian Period
http://www.ucmp.berkeley.edu/permian/permian.php
This period brought with it the mass extinction of underwater creatures. And is also thought to have been the beginning of the age of dinosaurs. That means dinosaurs were introduced in this period. -
Mesozoic era
This era started around 252 million years ago and ended 66 million years ago -
Triassic Period
http://www.livescience.com/43295-triassic-period.htmlThe continent of Pangea. Very little aquatic life due to the Permian extinction. Some reptiles move back into the ocean. This brought with it the specie ichythosaurs. Later in this period they evolved into dolphins and other strictly aquatic forms. Two groups of animals survied the last extinction. Two groups of reptiles. One group went on to form the Dinosaurs the other group went on to form early mammals -
Jurassic Period
http://www.ucmp.berkeley.edu/mesozoic/jurassic/jurassic.phpThis period brought with it massive plant eating dinosaurs as well as vicious smaller predators. Also the introduction of flying reptiles such as the pterosaurs. In the aquatic life sharks alligators and rays started to resemble present day aquatic life. Near the end of this period the T-rex and triceratops were introduced. -
Cretacous Period
http://www.ucmp.berkeley.edu/mesozoic/cretaceous/cretaceous.phpIn this period dinosaurs still roamed the earth. Flowering plants were created. Many insects diversified. Grasshoppers, ants, butterrflies and many other insects were introduced to earth. Near the end of this period and the beginning of the tertiary is where the great extinction occured. All the dinosaurs basically went extinct. -
The Palogene
http://science.nationalgeographic.com/science/prehistoric-world/paleogene/Known as the age of the mammals. Begins after the extinction of non flying dinosaurs. Larger mammals appeared. Many single celled organisms died. Many of the species living in this period closely represent the species we see today -
Cenozoic era
The Cenozoic era started 66 million yars ago is the current era we live in. -
Neogene Period
http://science.nationalgeographic.com/science/prehistoric-world/neogene/Mainly in this period species migrted to different regions. The temperatures dropped forcing species to adapt -
Quaternary Period
http://science.nationalgeographic.com/science/prehistoric-world/quaternary/With this period came the introduction of early hominids (our ancestors). Many species evolved and disappeared.
