Formation of Earth.

Modern science divides the Earth development into four eras. As the earth was formed except the Pre-Cambrian as the rest is made up of these shorter periods. Early Planet Dinosaurs who lived during the Mesozoic era these  are made up of three periods known as the Triassic, Jurassic and the Creataceous.

As the planet first formed Early Earth.
It was a rock like mass finds its orbit within solar system outer part of the galaxy in the milky way the planet cools down. Atmosphere by meteorite Oceans develop as water cycle grow. Archaean 4.5-2.5 bya single cell animal seem to appear, as to feed in the now moving liquid oceans. Proterozoic 2.5 bya – 550 mya these were simple multicellular animals, such as trilobites feed of filtration. Cambrian 550-510 Mya these were important shelled animals such as trilobities these exo skeleton. Ordovician 510-438 mya these were fish endo skeleton along dorsal used gills create oxygen power. Pleozoic Era  550-250 mya earth been transformed into a habitable planet it was the start of the world.

Silurian 410-355 mya where had relative simple plants. Devonian 410-355 mya  amphibians wingless insects and ferns very common today.  Carboniferous from 355-290 mya conifers, reptiles and flying insects. Permian  290-250 mya sea reptiles and land eating reptiles. Mesozoic Era 250-65 Mya