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66
End Cretaceous
This extinction occurred during the "Age Dinosaurs" and killed all of them with the exception of birds. The earth was the closet to what it looks like today in terms of land mass and structure. Fossil evident found all over the world indicates the mass extinction of the dinosaurs. The Deionychus, mosasurs, and ichthyosurs were some of the many organism to become extinct. It is widely believed that a large meteor struck the earth causing a plethora of disasters such as climate change. -
199
End Triassic
Over 80% of life went extinct during this extinction. It is believed that either volcanic activity or melting of permafrost lead to an increased greenhouse effect which devastated life on Earth. Ammonioids, conodonts, and varies families of brachiopods went extinct. Phylloceratid ammonoids survived and developed into the first dinosaurs. The End Triassic extinction gave way for dinosaurs to become the dominant animal species. -
252
End-Permian
This extinction killed over 95% of marine and 70% of terrestrial species. Organisms such as the acanthodians, pelycosaurs, and placodorms went extinct. Theories for the extinction range from global warming, a meteor, and methane poisoning. This extinction is the most severe of the major 5 -
360
Late Devonian
This extinction primarily affected sea organisms. Between 80-90 percent of species went extinct. Organisms that were killed included placedorms, jaw less fish, and trilobites. There are a range of theories for the mass extinction ranging from climate change to lack of dissolved oxygen due to terrestrial plant life. In fact terrestrial life was largely unaffected by the extinction. The marine creatures that did survive would become the first land creatures. -
444
Late Ordovician
The extinction took place 445.2 million to 443.8 million years ago and is considered twice as severe as the K-T, it killed 85% of the organisms at the time, which were mostly marine organisms at the time.Fossil records indicate that a large number of organisms died during the same time period. Organisms that went extinct were Brachiopods, Bryozoans, trilobites. It is believed that drastic climate change killed the organisms.
