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Period: 450 BCE to 440 BCE
Late Ordovician
Occurred 439 million years ago
Removed about 85% of species of marine animals
During this time, most of the world's land masses had come together to create the supercontinent, Gondwana (Africa, S. America, Antarctica, and Australia). Scientists believed two major events resulted in this extinction: glaciation and falling sea levels. Theories suggest that the Earth was covered in a vast quantity of plants that they removed too much carbon dioxide from the air, reducing the temperature -
443 BCE
Late Ordovician Species Lost #1
Trilobite family Trinucleidae -
443 BCE
Late Ordovician Species Lost #2
Trilobite family Bathyuridae -
443 BCE
Late Ordovician Species Lost #3
Brachiopod genus Thaerodonta -
439 BCE
Late Ordovician Cont.
It appears that this extinction occurred in phases. During this time, a major ice age was occurring in the southern hemisphere and climates were cooling worldwide. The first wave happened as the temperature drastically decreased and the second wave resulted in climates warming at the end of the ice age. This caused trilobites, brachiopods, and graptolites to die off in large numbers. The time period was when organisms such as corals appeared on the earth for the first time. -
375 BCE
Late Devonian Cont.
During the time, large trees evolved and formed the first forests. When plant life expanded, they used up more carbon dioxide. When plants decayed, the material would be buried underground and ultimately form into coal. -
375 BCE
Late Devonian Species Lost #1
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375 BCE
Late Devonian Species Lost #2
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375 BCE
Late Devonian Species Lost #3
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Period: 375 BCE to 360 BCE
Late Devonian
Occurred 375 million years ago
75% if species lost
Had the greatest effect on marine animals such as brachiopods, trilobites, and reef-building organisms; the reef-building organisms almost completely disappeared. Stromatoporoids disappeared.
A variety of causes have been proposed for this mass extinction These include asteroid impacts, global anoxia (widespread dissolved oxygen shortages), plate tectonics, sea level changes and climatic change. It is often known as the “Age of Fishes” -
299 BCE
End Permian Cont.
After this event, marine life developed a complexity not seen before and snails, urchins, and crabs emerged as new species.
There is geological evidence that the amount of oxygen dissolved in ocean water was reduced and led to changes in ocean circulation.
On land, these events led to the "Age of Dinosaurs". Many scientists say after this period, life on Earth was never the same again. The geography on earth included massive areas of land and water. By the end of this period, Pangea was formed. -
Period: 298 BCE to 251 BCE
End Permian
251 million years ago
96% of species lost, also more that 3/4 of marine animal species
A new group of corals appeared such as stony or scleractinian corals. On land, primitive synapsids like mammals vanished.
It was most likely caused by an enormous volcanic eruption that filled the air with carbon dioxide which fed different kinds of bacteria that began emitting large amounts of methane. The Earth warmed, which made the oceans acidic -
252 BCE
End Permian Species Lost #1
Trilobites -
252 BCE
End Permian Species Lost #2
Tabulate corals -
252 BCE
End Permian Species Lost #3
Rugose corals -
Period: 252 BCE to 201 BCE
End Triassic
199-214 million years ago
About 75% species lost
The blame has been placed on an asteroid impact, climate change, and flood basalt eruptions.
All major groups of marine invertebrates survived, but suffered major losses. On land, the phytosaurs (crocodile-like animals) were hit.
The supercontinent of Pangea began to break apart. Volcanic activity on a massive scale introuduced CO2 into the atmosphere. This led to more global warming changes -
201 BCE
End Triassic Species Lost #1
Phytosaurus -
201 BCE
End Triassic Species Lost #2
Therapsid -
201 BCE
End Triassic Species Lost #3
Rauisuchian -
Period: 145 BCE to 66 BCE
End Cretaceous
66 million years ago
It is known as the end of all dinosaurs except birds and created opportunities for mammals.
Vertebrates were lost at the end while marine invertebrates also disappeared.
There are several lines of geological evidence that indicate that an asteroid around 10 km hit the Earth at the end of this period. The evidence includes an ancient impact crater in the Yucatan Peninsula of Mexico. -
66 BCE
End Cretaceous Cont
The impact from the asteroid would have created a large dust cloud which would have prevented photosynthesis on land and in the oceans. As plants and plankton died, the mass extinction continued and expanded up the food chain. It eliminated herbivores and carnivores
Vertebrates that were lost at the end of the Cretaceous include the flying pterosaurs, and the mosasaurs, plesiosaurs and ichthyosaurs of the oceans. -
66 BCE
End Cretaceous Species Lost #1
Ammonite -
66 BCE
End Cretaceous Species Lost #2
Gryphaeid Oyster -
66 BCE
End Cretaceous Species Lost #3
Inoceramid
