Eocene Guide, Meaning , Facts, Information and Description
| This epoch is part of the Tertiary period and the Paleogene subperiod. |
| Pliocene |
| Miocene |
| Oligocene |
| Eocene |
| Paleocene |
The name Eocene refers to the dawn of modern ('new') mammalian fauna that appeared during the epoch.
| Table of contents |
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2 Eocene climate 3 Eocene paleogeography 4 Eocene Flora 5 Eocene Fauna 6 Eocene Oceans 7 See also 8 External References |
Eocene subdivisions
The Eocene is usually broken into lower and upper subdivisions. The Faunal stages from youngest to oldest are:
Eocene climate
Marking the start of the Eocene, the planet heated up in one of the most rapid (in geologic terms) and extreme global warming events recorded in geologic history. It is currently identified as the Paleocene-Eocene Thermal Maximum or Initial Eocene Thermal Maximum (PETM or IETM). This was an episode of rapid and intense warming (up to 7°C at high latitudes) that lasted less than 100,000 years [1]. The Thermal Maximum lasted some 200,000 years, and provoked a sharp extinction event that strongly distinguishes Eocene fauna from the ecosystems of the Paleocene.
Climates remained warm through the rest of the Eocene, although slow global cooling, which eventually led to the Pleistocene glaciations, started around the end of epoch, as ocean currents around Antarctica cooled (see paleogeography below).
Eocene paleogeography
During the Eocene, the continents continued to drift toward their present positions.
At the beginning of the period, Australia and Antarctica remained connected, and warm equatorial currents mixed with colder Antarctic waters, distributing warmth around the world, keeping global temperatures high. But when Australia split from the Southern continent around 45 mya, the warm equatorial currents were deflected away from Antarctica, and an isolated cold water channel developed between the two continents. The Antarctic region cooled down, and the ocean surrounding Antarctica began to freeze, sending cold water and iceflows north, reinforcing the cooling.
The norhern supercontinent Laurasia began to break up, as Europe, Greenland and North America drifted apart.
In western North America Mountain building started in the Eocene, and huge lakes formed in the high flat basins among uplifts.
Europe saw the Tethys Sea finally vanish, while the uplift of the Alps created the Mediterranean Sea and a another shallow sea with island archipelagos to the north. Though the North Atlantic was opening, a land connection appears to have remained between North America and Europe, as the faunas of the two regions are very similar.
India continued its journey away from Africa, and began its collision with Asia, folding the Himalayas into existence.
Eocene Flora
At the beginning of the Eocene, the high temperatures and warm oceans created a balmy moist environment, with tropcial rainforests spreading throughout the world, from the North pole to South pole.Cooling began mid-period, and by the end of the Eocene, the inland continents had begun to dry out, with forests thinning out considerably in some areas. Grasses were still confined to river banks and lake edges, and had not yet expanded into plains and savannahs.
The cooling also brough seasonal changes, and deciduous trees, better able to cope with large temperature changes, began to overtake tropical species. By the end of the period, deciduous forests covered large parts of the northern continents, including North America, Eurasia and the Arctic, and rainforests held on only in equatorial South Amercia, Afica, India and Australia.
Antarctica, which began the Eocene fringed with sub-tropical rainforest, became much colder as the period progressed, wiping out the heat-loving tropical flora, and by the beginning of the Oligocene the continent hosted deciciduous forests and vast stretches of tundra.
Eocene Fauna
The oldest known fossils of most of the modern mammal orders appear in a brief period during the early Eocene. At the beginning of the Eocene several new mammal groups arrived in North America. These modern mammals, like artiodactyls, perissodactyls and primates, had features like long, thin legs, feet and hands capable of grasping, as well as advanced teeth adapted for chewing. Dwarf forms reigned. All the members of the new mammal orders were small, under 10 kg; based on tooth size, Eocene mammals were only 60 per cent of the size of the primitive Paleocene mammals that had preceded them. They were also smaller than the mammals that followed them. It is assumed that the hot Eocene temperatures favoured smaller animals that were better able to manage heat.
Both groups of modern ungulates (hoofed animals) became prevalent due to a major radiation between Europe and North America. Early forms of many other modern mammalian orders appeared, including ungulates, bats, proboscidianss, primates, and rodents and marsupials. Older primitive forms of mammals declined in variety and importance. Important Eocene land fauna are found in western North America, Europe, Patagonia, Egypt and South-East Asia. Marine fauna are best known from South Asia and the southeast United States.
During the Eocene plants and marine faunas became quite modern. Many modern bird orders first appear in the Eocene.
The Eocene oceans were warm and teeming with fish and other sea life. The first Carcharinid sharks appeareds, as did early marine mammals, including Basilosaurus, an early species of whales, which are thought to be descended from land animals, the hoofed predators, mesonychid.
This is an Article on Eocene. Page Contains Information, Facts Details or Explanation Guide About Eocene Eocene Oceans
See also
External References