Archeozoic Era (4500-1500 million years ago): This is the first Era to have geologic record. In this early stage of the earth the surface changes from molten to rock. The continential plates also form during this timeline. The atmosphere of the earth is made up from 75% nitrogen & 15% carbon Dioxide. These are known as Prokaryotic cells. They have free floating DNA, have no nucleus, and lack membrane-bound organelles associated with higher forms of life. Also cyanobacteria first formed which is the first cell to create oxygen.

Proterozoic Era (2500 to 542 million years ago): In this Era Cells with nucleus and organelles. The important function of organelles is that they perform special functions that are needed for the evolution of fungi, protists, plants, and animals. Nearing the end of this Era soft body organisms appear such as jellyfish.

Paleozoic Era (542 to 151 million years ago): This is the era which much change had occurred. The first hard parts species started to appear such as primitive fish, coral, plant life, Vertebrate animals form along with arachnids, and wingless insects. During the end of the Paleozoic Era is the Permian Period in which there is a great extinction which wipes out roughly 95% of all life forms. It has not been concluded on what caused this, but there is evidence that when the many continents formed one massive one called Pangaea it caused the earth to be unstable and mass volcanoes appeared destroying the oxygen level balance.

Mesozoic Era (251 to 65.5 million years ago): This is the dinosaur age. The Mesozoic is broken up into three periods. The Triassic, the Jurassic, and the Cretaceous Period. In the Triassic period there were many primitive dinosaurs forming and many species of marine reptiles. Some of the first species of dinosaurs were the Plateosaurus, Eoraptor, Herrerasaurus, Pisanosaurus, Saturnalia, Staurikosaurus. In the Jurassic Period dinosaurs such as Diplodocus and Apatosaurus, and carnivores such as Allosaurus flourish. Also the first reptiles with primitive abilities to attempt flight appeared such as Archaeopteryx. The dinosaurs of this time have gotten much more larger in size and many ocean dwelling reptiles were becoming extinct. In this Period the evolution of Sauropods(Long-necked dinosaurs) was at its peak. During the Cretaceous Period the Ceratopsidae family begin to form which includes many plated dinosaurs with defense body features such as spikes such as the Triceratops. At the end of this Period and Era there is a large extinction situation which completely wipes out all dinosaurs living on the earth. Although not proven there is several theories on why this has happened.

Cenozoic Era (65.5 million years ago to today):The oldest known modern mammals diversify and radiate across the continents. Appearance of the first elephants, horses, and other hove mammals exist in this Era.