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By Michael Davis
Josh Shindler
Andrew Baldwin
What’s a mass extinction?
• a sharp decrease in the number of species in a
relatively short period of time.
There different ways a mass extinction can
occur including…
Global warming
Ice age
And more…
How many mass extinctions have
there been?
Ordovician-Silurian Extinction
• 439 million years ago
• Caused by a drop in sea level as glaciers
formed, then by rising sea levels as
glaciers melted.
• Killed about 25% of marine families
• Killed 60% of marine genera
Late Devonian extinction
• About 364 million years ago
• Not clear if it is 2 large mass extinctions or
a series of small extinctions
• About 22% of marine families were killed
• About 57% of the genera were killed
• Suggested that a asteroid impact was the
prime cause
Permian-Triassic extinction
• Most likely due to volcanic eruption,
• an asteroid impact
• or a near by super nova.
Informally called the “Great Dying”
Occurred about 251 million years ago
It was the most severe extinction
96% of all marine species were killed
70% of terrestrial vertebrate were killed
the extinction took a few million years
Normal levels of biodiversity did not become
present until 6 million years after the end of the
End Triassic extinction
Power Point Template
• 199 million to 214 million years ago
• caused by massive floods or lava erupting
from central Atlantic province – an event
that triggered the opening of the Atlantic
• The volcanism may have lead to deadly
global warming
• 22% of Marine families
• 52% of marine genera
• Vertebrate deaths unknown
Cretaceous-Tertiary extinction
• No one knows exactly how this Mass
Extinction happened and why it happened
at such a rapid rate. Scientists have many
theories but it boils down to about one
major one and a few others due to
Occoms razor.
• The first and the most favored theory is
that an asteroid hit somewhere in the golf
of Mexico in the Yucatan Peninsula 65
million years ago. The Asteroid impact is
site is called the Chixclub and is
approximately 200 Kilometers across
making the asteroid itself about 9 miles
• caused Forest fires to start and ignited
volcanic eruptions all over the glob as well
as tidal waves, severe storms that would
eliminated all sunlight. It would be six
months before sunlight would reach the
ground after such a blow. The dinosaurs,
even in their prime, stood no chance
without sunlight and plant life, ending the
dinosaurs 165 million year reign.
• One of the other theories is that climate change
killed all of the plant eating dinosaurs due to
lack of food from the climate change. The
cretaceous period was tropical and so were
almost 50 percent of the plants. If the
temperature was to change drastically the plant
eater’s food would slowly dwindle. With the
plant eaters becoming extinct the carnivores
would soon run out of food as well.
• Volcanic eruptions have also been
theorized to have killed of the dinosaurs.
When volcanoes erupt they send clouds of
dust, sulfuric acid, and poisonous gas that
would have made it impossible to breath.
This would result in the blocking of
sunlight and a severe climate change.
This would have been nearly impossible to
survive in this environment
• Which do you think killed the dinosaurs????
The Big Five
• Ordovician-Silurian extinction - 439 million
years ago,
Late Devonian extinction - 364 million years
Permian-Triassic extinction - 251 million
years ago
End Triassic extinction, - 199 million to 214
million years ago
Cretaceous-Tertiary extinction, about 65
million years ago
The sixth mass extinction?
• This extinction is referred to as the
Holocene extinction. This is named after
what geologists call the period we as
humans have been in. The immense
amount of extinction during this period of
plants and mammals has constituted is as
a mass extinction to many scientists. The
extinctions include birds, mammals,
reptiles, and amphibians.
• This extinction is thought to have started once
Homo sapiens started dispersing outward from
Africa on the land bridges, hunting and
gathering was the start of the extinctions
induced by man. Today approximately 1,000
species out of the worlds 10,000 are on the
verge of extinction. There is no conclusive
evidence but it is estimated that since Homo
sapiens began hunting and gathering some
500,000 – 1,000,000 species have become
extinct, from over hunting, population, and
most importantly pollution.
• What do you think, are we in the midst of
a mass extinction???