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Cambrian 540-490 MYA
This period lasted about 53 years and marked a dramatic burst of evolutionary and changes in life. Some animals the evolved during this times period were the chordates, they resembled clams and arthropods. -
ordovician 45 MYA
This period lasted about 45 million years. During this period the area north of the tropics was almost entirely ocean, and most of the world's land was collected into the southern supercontinent Gondwana. Some of the living species that were in this time period were bryozoans, corals, crinoids, and many kinds of brachiopods, snails, clams, and cephalopods appeared for the first time in the geologic record in tropical Ordovician environment -
Silurian 443 MYA
This time period was about 443 million years ago. during this time the continental landmasses were low and the sea levels were rising. Some animals that made their first appearances were leeches, brachiopods, and molluscs. -
Devonian 358 MYA
This time period occurred about 358 million years ago. This is also known as the "Age of fishes". Plants continued to make an evolutionary progress during the Devonian. -
Carboniferous 299 MYA
This time period was about 299 million years ago.There was rich deposits of coal. The coal occurred throughout northern europe, Asia and mid-western and eastern north America. The Carboniferous generally had a more uniform, tropical, and humid climate than exists today. Seasons if were indistinct. These observations are based on comparisons between fossil and plant morphology. The Carboniferous plants resemble those that live in tropical and mildly temperate areas today. -
Periam Period 251 MYA
The permian diversification of the early amniotes into the ancestral groups of the mammals, turtles, lepidosaurs and archosaurs. The world during this period was dominated by two continents known as Pangea and Siberia surrounded by a global ocean called Panthalassa. -
Triassic 251-199 MYA
he Triassic Period was the first period of the Mesozoic Era and occurred between 251 million and 199 million years ago. It followed the great mass extinction at the end of the Permian Period and was a time when life outside of the oceans began to diversify. -
Jurassic 199-145 MYA
During this time period there were great plant eating dinosaurs roaming the earth. There was oceans full of fish, squid and coiled ammonites. The first birds. -
Cretaceous 145-66 MYA
The Cretaceous period began 145 million years ago and ended 66 million years ago; it followed the Jurassic Period and was succeeded by the Paleogene Period. The climate was generally warmer and more humid than today. Dinosaurs were the dominant group of land animals. -
Tertiary 66-2.6 MYA
Occurred 66-2.6 MYA. This was the first two periods of the cenozoic era. The Tertiary was an interval of enormous geologic, climatic, oceanographic, and biological change. It spanned the transition from a globally warm world containing relatively high sea levels and dominated by reptiles to a world of polar glaciation. -
Quaternary 2,588,000 Years - Now
There has been rapid changes of climate and sea levels environments worldwide have been altered. These variations in turn have driven rapid changes in life-forms, both flora and fauna. Beginning some 200,000 years ago, they were responsible for the rise of modern humans. The Quaternary is one of the best studied parts of the geologic record.
