Transcript Mass Extinction

Mass Extinction
By Joe Baraona
What is Mass Extinction?
“The extinction of a large number of
species within a relatively short
period of geological time, thought to
be due to factors such as a
catastrophic global event or
widespread environmental change
that occurs too rapidly for most
species to adapt.”
Five Major Mass Extinctions in
History
Ordovician–Silurian Extinction Event ~440 Million
Years Ago
Late Devonian Extinction Event ~ 370 Million Years
Ago
Permian–Triassic Extinction Event ~ 250 Million Years
Ago
Triassic–Jurassic Extinction Event ~ 205 Million Years
Ago
Cretaceous–Tertiary Extinction Event ~ 65 Million Years
Ago
Five Major Mass Extinctions in
History
Ordovician–Silurian Extinction Event
•Occurred 447.3 Million Years Ago
•~50% of all Marine Species Died
•Main Species Effected: Brachiopods,
Bryozoans, Trilobite, Conodont and
Graptolite families.
•Mainly Caused By Sharp Increase In
Extinctions
•Possible Causes: Elongated Ice Age,
Gamma Ray Bursts, Volcanism and
Weathering
Late Devonian Extinction Event
•Occurred 370 million years ago
•Overall, 19% of all families and 50% of all
genera went extinct.
•Affected primarily marine life
•Reef building organisms almost completely
destroyed
•Primary cause: Ocean anoxia
•Possible Causes for Anoxia: Global cooling,
oceanic volcanism, meteor impact
•Extinction caused by speciation rather than
extinctions
Permian–Triassic Extinction
Event
•Occurred 251.4 Million Years Ago
•Earths most severe extinction “The Great
Extinction”
•96% of marine species, 70% of terrestrial
vertebrate and 83% of all genera die
•Possible causes of extinction: climate change,
impact events, anoxia, volcanism and methane
hydrates in the ocean
Triassic–Jurassic Extinction Event
•Occurred 205 Million Years Ago
•Affected 20% of all marine families, therapsids
and large reptiles
•At least ½ of all living species died during this
time
•Allowed for the domination of dinosaurs
•Possible causes for extinction: gradual climate
change, asteroid impact and volcanism
Cretaceous–Tertiary Extinction Event
•Occurred 65.5 million years ago
•Cause of the extinction of all non avian
dinosaurs
•Allowed for the expansion of birds and
mammals
•Possible reasons for extinction: volcanism or
an impact event
•On March 4, 2010, a panel of 41 scientists
agreed that the Chicxulub asteroid impact
triggered the mass extinction
Asteroid Theory
Video
Opera - [YouTube - How many asteroids hit Earth?- What Really
Killed the Dinosaurs? BBc Documentary]
Citations
http://www.myfreewallpapers.net/fantasy/wallpapers/comet-impact.jpg
-Comet Impact Image
http://dictionary.reference.com/browse/mass+extinction
-Mass Extinction definition
http://en.wikipedia.org/wiki/Ordovician–Silurian_extinction_event
-Ordovician- Silurian Extinction
http://en.wikipedia.org/wiki/Late_Devonian_extinction
-Devonian Extinction
http://en.wikipedia.org/wiki/Permian–Triassic_extinction_event
-Permian Triassic Extinction
http://en.wikipedia.org/wiki/Triassic–Jurassic_extinction_event
-Triassic Jurassic Extinction
http://en.wikipedia.org/wiki/Cretaceous–Tertiary_extinction_event
-Cretaceous Tertiary Extinction
http://en.wikipedia.org/wiki/File:Extinction_intensity.svg
-Graph
http://en.wikipedia.org/wiki/File:Chicxulub_radar_topography.jpg
-Impact Image
http://en.wikipedia.org/wiki/File:Mexico's_Territorial_Evolution.png
-Mexico