During the Miocene and Pliocene epochs: - Mountain ranges like the Sierra Nevada and Andes formed due to plate tectonics. The Isthmus of Panama also began to form, connecting North and South America. - Climates became drier globally as continental positions changed, isolating Antarctica and severing connections like the Tethys Sea. Forests reduced and grasslands expanded. - Life diversified with new forms of mammals, birds, plants and sea life like kelp forests. Megapiranha, a large piranha up to 1 meter long, existed in South America during the Miocene. - In the Pliocene, North and South America joined while

1. Cenoz oic : N e og e n e : M i o c e n e a n d P l i o cene
La c e y Kas t e n / Ap ri l 2 0 1 2

2. Continental Movement: Miocene
North America:
• Sierra Nevada & Cascade mountain
ranges are formed.
• The Panama isthmus begins to form
a connection between North and South
America.
Eurasia:
• The Tethys Sea connection between
the Mediterranean and Indian Ocean is
severed
• The Paratethys barrier is periodically
disrupted allowing migration
Africa:
• Rifting occurred in East Africa
• The African-Arabian plate united with
Eurasia
Antarctica:
• Became isolated from the other
continents leading to the formation of a
circumpolar ocean circulation
South America:
• The Andes mountains rise due to plate
tectonics.

3. Climate Changes: Miocene
North America:
• Non-seasonal and drier mid-continent climate
occurred due to mountain range development
• The increasing occurrences of drought and an
overall decrease in absolute rainfall promoted
drier climates.
• Grasslands began to spread, radiating large
herbivores and carnivores into extinction.
Australia:
• An overall increase aridity occurred as it
continued to drift northwards
• The continent went through many wet and dry
periods, decreasing rainforests.
Eurasia:
• Severing of the Tethys Sea caused the
increase in aridity in Southern Europe.
Africa:
• The union of the continents of Africa and
Eurasia caused interruption and contraction of
the Tethys Sea, thereby depleting the primary
source of atmospheric moisture in that area.
Antarctica:
• The antarctic polar ice cap was allowed to
develop. This accelerated the development of
global seasonality, aridity, and enhanced global
cooling.

4. Life Forms: Miocene
• A major shift occurred when
kelp forests and grasslands
became more diversified.
• Open vegetation systems
(deserts, tundra, and
grasslands) became more
common than closed vegetation
systems (such as forests).
• This led to a rediversification
of temperate ecosystems and
many morphological changes in
animals.
• Mammals and birds in
particular developed new
forms, whether as fast-running
herbivores, large predatory
mammals and birds, or small
quick birds and rodents.
• By the end of the Miocene 95%
of modern seed plant families
existed.
• Kelp forests appeared for the
first time, as did sea otters and
other critters unique to those
environments.

5. Miocene Life Form: Megapiranha
Name: Megapiranha ‭(‬Big piranha‭)‬.
Size: Estimated up to‭ ‬1‭ ‬meter long.
Species: M.‭ ‬paranensis‭ (‬type‭)‬.
Known locations: Argentina.
Diet: Uncertain,‭ ‬probably carnivorous,‭
‬but teeth could have been used for a
herbivorous diet.
Time period: Tortonian of the Miocene.
Fossil representation: Premaxillae teeth.

6. Continental Movement: Pliocene
North America:
• The joining of North and South America
officially happened at the Isthmus of
Panama
• The Cascades, Rockies, Appalachians,
and the Colorado plateaus were uplifted
• The Sierra Nevada was elevated and
tilted to the west
Eurasia:
• The Indian and Asia plates interacted,
forming the Himalayas
Antarctica:
• Large polar ice caps began to develop
and the continent became frozen

7. Climate Changes: Pliocene
• Climate cooling was significant in the • This long term cooling, actually
Pliocene epoch.
started in the Eocene and continued up
to the ice ages of the next epoch.
• The beginning of the epoch saw
numerous fluctuations in temperature, • Generally, the climate was warmer
which gave way to the general cooling than modern day temperatures,
trend towards the end of the Pliocene. although significant cooling was
occurring on a global scale.

8. Life Forms: Pliocene
• Grasslands continued
to develop as well as the
grazers that lived off of
them.
• On land, the creation
of a land bridge
between North and
South America enabled
species to migrate
between the two
continents.
• This led to a migration
of armadillo, ground
sloth, opossum, and
porcupines from South
to North America

9. References -“Megapiranha.” Prehistoric Wildlife. Web. 09 Apr. 2012. <http://www.prehistoric-wildlife.com/
species/m/megapiranha.html>.
“The Miocene Epoch.” UCMP. Web. 09 Apr. 2012. <http://www.ucmp.berkeley.edu/tertiary/miocene.
php>.
“PIRANHA PICTURES: Yard-long “Megapiranha” Fossil Found.” National Geographic. National
Geographic Society. Web. 09 Apr. 2012. <http://news.nationalgeographic.com/news/2009/06/photogalleries/giant-piranha-pictures-evolution/index.html>.
“The Pliocene Epoch.” UCMP. Web. 09 Apr. 2012. <http://www.ucmp.berkeley.edu/tertiary/pliocene.
php>.