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Precambrian
The presence of stromatolites indicates that shallow seas covered much of Earth during intervals in this period. Nearly half of the valuable mineral deposits in the world occur in the rocks of this period. -
Period: to
IDeleon p.8
Geologic Timescale -
Cambrian
Trilobites appear. Shelled brachiopods appear. -
Ordovician
There is very little plant life during this period. Colonies of tiny invertebrates call graptolites florished and vertebrates appear, fish did not have jaws or teeth and their bodies were covered with bony plates. -
Silurian
Eurypterids, sea stars and coral become more common. Vascular land plants and animals, such as scorpions begin to evolve on land. -
Devonian
Huge plants begin to develop, early amphibians form. Age of fishes, fish that can breathe out of the water and spend time on land form. -
Mississippi
Swamps and forests cover the land. Early reptiles resembling large lizards appear. -
Pennsylvania
Giant cockroaches appear. Coal deposits form. -
Permian
Appalachian Mountains are created because of the collision of tectonic plates and savannahs form. Environmental change causes mass extinction of sea invertebrates as the seas retreat. -
Jurassic
Flying reptiles called pterosaurs are in the air now. Woah those dinos are getting big and dominate the land, lizard hipped and bird hipped appear, carnivores and herbivores have arrived. -
Cretaceous
First flowering plants appear, angiosperm. Impact hypothesis, dinosaur mass extinction. -
Paleocene
First primates evolve. Small rodents evolve. -
Eocene
Flying squirrels, whales and bats appear. World wide temperatures drop about 4 degrees celsius. -
Oligocene
Himalayas develop due to uplifting caused by the Indian subcontinent and Eurasian continents colliding. Many early mammal become extinct, clams and snails flourish. -
Miocene
Antarctic icecaps begin to form. Mediterranean Sea dries up and refills several times due to tectonic forces and dropping sea levels. -
Pliocene
Various species migrated between continents across land bridges. First modern horses appear. -
Pleistocene
Homosapien appeared and are hunters. Species that did not evolve to survive extreme cold moved to warmer climate areas or became extinct. -
Holocene
The last glacial period ended and sea levels rose, Great Lakes formed. Modern human developed agriculture and used tools made of bronze and iron. -
Triassic
Welcome to the world of the dinosaur. Enter the squirrel sized dinosaur and the first forest dwelling mammals appear. Ichthyosaurs are living in the ocean, new invertebrates call ammonite develop. -
Anthropocene
Some scientists believe that human kind has caused mass extinctions of plant and animal species, polluted the oceans and altered the atmosphere. There is argument as to when this epoch began, some scientists think it began with the industrial age in the early 1800's others think it began with the automatic age in the 1950's.
