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Transcript of Oligocene Epoch
Lasted from about 34 mya to about 23 mya
Cretacious Period Paleogene Period Neogene period What is the climate like? Cooling temperatures led to changes in habitats.
Rainforests gradually gave way to temperate deciduous forests and grasslands (except in South America, where rainforests emerged)
The rise of grasslands also allowed for the evolution and expansion of many groups of animals (grazing ungulates, for example)
Oceans also cooled, affecting the organisms by either forcing them to move or adapt to the cooler temperatures.
...and more terrestrial events! Antarctica likes to cause trouble! As it breaks off from from South America (and forms a passage called the Drake Passage), it allows cold water from deep depths to flow and cool down the planet, in the process forming its own ice cap. A pathway between Australia and Tasmania also opened up.
The Tethys Sea, between northern and southern
Eurasia, began to close up, affecting current
circulation. The collision of these continents
built new mountain ranges and also contributed
to global cooling by drawing carbon dioxide from
the atmosphere. Terrestrial events! Life! First appearing during the Oligocene: Elephants with trunks, diurnal raptors, beavers, New World monkeys Sources! What is the climate like? Life and Migration! What makes the Oligocene so special?
Appearance of first elephants with trunks!
Expansion of grasslands! (and more grazing animals!)
Takeover of Asian animals!
Time of transition: Tropical Eocene Modern Miocene Decline in temperatures and precipitation, leading to an increase in glaciation and decline in sea levels. Part of this cooling can be blamed on the Antarctic Circumpolar Current, which brought cold and deep water to the surface.
The single largest volcanic eruption, from the La Garita Caldera, interrupted the depression in temperatures.
Changes in temperature were slow, so animals could adapt to the shifting climate. 8.6 Celsius 2 Celsius Polly, P. David. "The Oligocene Epoch." Geologic Time Scale. N.p., 10 Jun 2011. Web. 5 Feb 2013. Scotese, Christopher R., ed. Paleomap Project. N.p., n.d. Web. 5 Feb 2013. Lutgens, F. & Tarbuck, E. (2009). Essentials of geology. (10 ed.). Pearson Education In the Oligocene era, the continents begin to drift toward their current positions, and are mostly in the correct positions except Eurasia.
Mountain building continues to occur in North America, but the Alps begin to form as the European plate collides with the Asian one.
Europe Alps Asia
Presumably there was a land bridge between Europe and North America, due to the similarity of fauna from the two regions. Dominant or increasing in population: Cats, dogs, primates. Cooling temperatures less forest, leads to more grasses diversification of horses and abundance of ungulates Miohippus
Diet: grass Pyrotherium Habitat: forests
Diet: plants Grasslands Heterotroph Autotroph Extinct or declining populations: Plants and animals associated with forests, especially rainforests. Reduced biodiversity in marine plankton.
Migration of species from Asia to North America via an assumed land bridge.
Mini extinction event, resulting in the extinction of several carnivorous species due to outcompetition.
Also involved the mass migration of Asian fauna into European areas, resulting in the further extinctions of some European species.