• Paleozoic era

    545 to 248 million years ago. The models suggest that rainstorms called monsoons affected the East coast and that interior of continent was very dry.A large number of animals evolved between 530 and 520 million years ago including trilobites and brachiopods (pictured at left).
    During the early and middle parts of the Paleozoic, most animals lived in oceans. Animals without backbones (such as corals, brachiopods, mollusks, and trilobites) were very common.
  • Mesozoic era

    251 to 65.5 million years ago.On land, dinosaurs were the dominant animals, while the oceans were populated by large marine reptiles, and Pterosaurs ruled the air. For most of this period, the climate worldwide was warm and tropical, and shallow seas covered low-lying landmasses.
    The Mesozoic era came to an end with the great terminal extinction event known as the K-T (Cretaceous-Tertiary) event.
  • Cenozioc era

    Cenozoic Era (65 mya to Present). As the dinosaurs perished at the end of the Cretaceous, the mammals took center stage. Even as mammals increased in numbers and diversity, so too did the birds, reptiles, fish, insects, trees, grasses, and other forms of life.After the Mesozoic's hot, wet, soggy, and muggy climate, the Cenozoic gave mammals a nice, cool atmosphere to evolve in (much to the dissappointment of dinosaurs, who died out because of it).
  • Precambrian Time

    4.5 billionto 452 million years ago. Some types of plants and animals that were around are Brachiopods, sea pens, trilobites, protozoas, arthropods, cnidarians, and annelids. New life forms are plants and animals. The climate was cold. Other that the process of accretion of material which formed the planet, the major event would probably have been the impact of a Mars sized protolanet with the young Earth which probably led to the creation of the moon. The presence of the moon has contributed.