Eocene 54'833'7 MYA

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Eocene54.8-33.7 MYA

• By Rachel Utsler

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Mass Extinctions

• Due to the warm climate many prominent species of
  the previous epoch went extinct.
• The Eocene ended with the disappearance of
  primates in the Northern Hemisphere.
• Surviving primates fled to Africa and Arabia. The
  later evolved in the Oligocene.

Vivveravus, a small mongoose-like carnivore from
the Eocene of North America.
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Dominant Species

• During this period land mammals dominated over
  other species.
• Mammals whose olfactory organs, which developed
  around fifty-five million years ago, were
  exceptionally adapt to the Eocene environment.
  These mammals were more able than others to
  travel from North America, to Europe, Greenland,
  and Iceland.

• This was a time period which included the
  evolution of primates that looked like living
  species.
• Modern orders of mammals evolved.
• Many archaic species surfaced the Earth.

Lemur (strepsirhines)
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Dominant Species

• Animals of the Eocene were more advanced than
  their ancestors from the Paleocene. Their hands
  had the capability to grasp and contained nails
  rather than claws.
• Species were found in on most continents with the
  exception of South America and Antarctica.
• A truly dominant species would be the
  (strepsirhines) or Lemurs because they still
  exist today. Predominately found in Madagascar,
  Africa, and Asia.

• Another species which survived was the
  haplorhines including monkeys, apes, and humans.
• Primates descended from the first anthropoids,
  which evolved in the Eocene.

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Earths Development
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Earths Development

• Movement continued among the continents.
• The Himalayan Mountains developed during this
  time period due to the continent that was to
  become India and the continent of Asia collided.
• North America separated from Europe and
  Australia, South America eventually broke free.
• First grasses appear, a resource for herbovores
  trees thrive. Some modern mammals appear
  advanced primates camels, cats, dogs, horses
  rodents

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Climate Changes

• Regarded as the warmest epoch of the tertiary.
• Subtropical conditions were to be found near the
  Artic Circle during the beginning. However, the
  climate and temperature deteriorated
  significantly causing for the beginning of
  another mass extinction.
•  The warm climate allowed for species to migrate
  elsewhere.

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Climate

• Nitrogen levels were contained from the previous
  era.
• Oxygen was increased then decreased and
  eventually leveled out.
• Carbon dioxide peaked and steadily declined.

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Organisms

• Primitive Eocene whales were discovered in the
  middle of the Eocene era around 35-40 million
  years ago.
• Average body length 45-70 feet. Wedge feet about
  five feet long. Two types of teeth. One was for
  holding prey and the other for slicing it up.
  Similar to fish and squid.
• Fossils of these whales are important because
  they show the evolution of modern whales.

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Time for Changes

• The ten million years fluctuating climate
  separated the Eocene from other epochs.
• The environment suffered the subtropical and
  tropical forest shrunk.
• Animals which once lived in these areas
  repositioned into other tropical environments.
  This caused for grass to take over and for land
  mammals to further develop.

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Geography

• Lush bountiful land.
• Mud and sand sediments conclude that the Eocene
  contained many plants due to the large amounts of
  pollen found.
• Fossilized wood and leaves were discovered from
  the Eocene.

Jurassic Garden
Western Australia Spongolite
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Theories

• One theory is that hydrocarbons released from
  subsea rocks caused for volcanic activity which
  might have triggered extinction.
• Off the coast of Norway thousands of hydrothermal
  vents in lava were found. These vents ultimately
  could have caused gases to rise fifty-five
  million years ago.
• Another theory stated that warm ocean currents
  was responsible for keeping Antarctica iced over
  during in the Eocene period thirty-five million
  years ago. However evidence has began to show the
  contrary and is calling for a revision of this
  theory.
• El Nino involves taking lake sediments and
  comparing them with the Eocene coupled climate
  model simulations to find the Pacific deep-ocean
  and high-latitude surface warming of 10C but
  little change in the tropical thermo cline
  structure, atmosphere-ocean dynamics, and ENSO,
  in agreement with proxies.
• This theory contrast with past and future
  hothouse climates and links the result to a
  permanent El Nino state, which is a long term
  global change.

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Sources

• www.earthmuseumsegs.uwa.edu.au/the_eocene_andjuras
  sic_gardens.
• www.mnh.si.edu/antro/humanorigins/faq/gt/cenozoic/
  eocene.htm.
• www.heatisonline.org/contentserver/objecthandlers/
  index.cfm.
• www.purdue.edu/UNS/html4ever/2004/04227.Huber.Anta
  rctica.html
• www.sciencemag.org