today’s topic evolution: extinction - verona public schools · 2015-06-13 · today’s topic...
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Today’s Topic Evolution: Extinction
Learning Goal:
SWBAT explain why creatures go extinct from
Earth, and why some recently-extinct creatures
have gone extinct.
Please take out your fill-in notes again,
and we will continue learning about
extinct creatures .
Homework
Complete the Simulating Adaptations Lab
(One Day Late)
Complete cattle, cows, and dogs articles.
(Three Days Late)
Complete the Conditions of Natural
Selection homework and History of
Evolution Research Assignment.
(Four Days Late)
Upcoming Test
Our next test will take place on
Wednesday, 4/15.
It will cover all of Evolution:
Biological Evolution
Natural Selection
Artificial Selection
Adaptations
Extinction
Succession
Today’s Fill-In Notes
We’re next going to work through the five
mass-extinction events that took place on
Earth.
After that, we are going to watch the
beginning of an episode of Cosmos
regarding one of the extinction events.
The Five Mass-Extinction Events
Throughout Earth’s history there have
been many extinction events.
However, there has been five mass-
extinction events that occurred in Earth’s
history.
In a mass-extinction event, over 50% of
all plant and animal life go extinct.
The Five Mass-Extinction Events
The Five Mass-Extinction Events that
occurred are:
a. The Ordovician-Silurian (450 – 440
Mya)
b. The Late Devonian (375 – 360 Mya)
c. Permian-Triassic (252 Mya) (Cosmos)
d. Triassic-Jurassic (201.3 Mya)
e. Cretaceous-Plaeogene (66 Mya)
The Ordovician-Silurian
The Ordovician-Silurian mass-extinction
occurred approximately 450 – 440 Mya at
the end of the Ordovician Period.
Typically large scale events, such as
mass-extinctions, mark the end of a
geologic time period.
During this time, 70% of all species on
Earth were killed.
The Ordovician-Silurian During this period of time, all life existed
in the oceans.
The Ordovician-Silurian However, two events occurred, an
estimated four million years apart, that
set off this mass-extinction event.
The Ordovician-Silurian First was the movement of the super-
continent of Gondwana.
Gondwana, through tectonic plate
movement, shifted towards the south.
This in turn led to
global cooling.
The Ordovician-Silurian As a result of this global cooling, glaciers
began to form all over the planet.
This caused a drop in sea levels, which
further killed off many creatures.
The Late Devonian
The Late Devonian mass-extinction
occurred approximately 375 – 360 Mya at
the transition from the Devonian Period
to the Carboniferous Period.
This extinction event caused 70% of all
creatures on Earth to perish.
The Late Devonian It is unclear what caused the mass-
extinction, but evidence suggests that it
was not one singular event that triggered
the extinction.
It is thought that several small events
occurred over the span of 20 million
years.
The Late Devonian This extinction event only appeared to
affected marine life.
Some theories as to what caused the
extinction event are changed to ocean
levels, or depletion of oxygen in oceans.
This would have been caused by volcanic
activity in the ocean.
The Triassic-Jurassic
The Triassic-Jurassic mass-extinction
occurred approximately 201.3 Mya at the
end of the Triassic Period.
This extinction event caused 70% - 75%
of all creatures on Earth to go extinct.
The Triassic-Jurassic
Land and air-dwelling dinosaurs survived
perfectly well through this extinction
event.
The Triassic-Jurassic
However, non-dinosaur aquatic creatures
in the oceans continued to dominate the
oceans.
The Triassic-Jurassic There are many theories as to what
caused the extinction event:
Gradual climate change
Sea-level fluctuations
Ocean acidification
The Triassic-Jurassic One theory suggests the possibility of an
asteroid impact.
However, none of these hypotheses have
any significant evidence to support them.
The Cretaceous-Paleogene
The Cretaceous-Paleogene mass-
extinction occurred approximately
66 Mya at the end of the Cretaceous
Period.
This extinction event caused 75% of all
creatures on Earth to go extinct.
The Cretaceous-Paleogene
This extinction event killed all non-avian
(non-flying) dinosaurs.
The Cretaceous-Paleogene This extinction event was believed to
have been caused by a massive
comet/asteroid impact.
The Cretaceous-Paleogene The impact had dire effects on the entire
globe’s environment.
The Cretaceous-Paleogene The dark line in the rock marks this event
The Cretaceous-Paleogene Sampling shows higher concentrations
(30x higher than naturally found on
Earth) of iridium in this region, which is
prevalent in meteors and comets.
It also corresponds
to ash and carbon,
as the impact
triggered many fires
(high O2 levels)
The Cretaceous-Paleogene The impact caused an impact-winter,
which is caused by an ejection of dust
and dirt into Earth’s atmosphere.
This dust and dirt
blocks sunlight from
entering, which
prevents
photosynthesis from
occurring in plants
and plankton.
The Permian-Triassic To learn about the Permian-Triassic
extinction event, we turn to our friend
Neil deGrasse Tyson.
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