Journal Entry #7: Here Today! Gone Tomorrow! Looking at Earths
history, there have been five major mass extinctions over the past
500 million years. Each one is thought to have annihilated anywhere
from 50 to 95% of all species on the planet. Organisms are still
becoming extinct today, and it has been recorded that during the
last 200 years more than 50 species of birds, more than 75 species
of mammals, and hundreds of other species have become extinct.
Explain how the term mass extinction is different from extinction.
What are some possible explanations of the mass extinctions that
have occurred in Earths past?
Slide 4
Mass Extinction is a time period during which there is an
especially high rate of extinction of species that occurs very
quickly, typically totally 50% or more of the existing
species.
Slide 5
Its normal for a species to go extinct, and an average rate of
one a year is the natural background rate. But over the past 4.5
billion years, there have been times when extinctions occurred at
100-1,000 times faster with the largest event wiping out 95% of all
species. Somewhere between 5 and 20 such mass extinctions have
occurred.
Slide 6
The Big Five Cretaceous-Tertiary K-T (65 million years ago)
Triassic-Jurassic ( 200 million years ago) Permian-Triassic (250
million years ago) Late Devonian (360 million years ago)
Ordovician-Silurian (444 million years ago)
Slide 7
Reading for Information (ACC) PURPOSE: 1. To look at the claims
of possible causes of mass extinctions in Earths past, and to see
if there is any scientific evidence to support them. 2. To see how
mass extinctions impacted Earths surface, atmosphere, climate, and
life.
Slide 8
Directions (ACC) Read and annotate the article on possible
causes of Earths mass extinctions. Think about- 1. How did this
claim cause a mass extinction. 2. Is there any evidence to support
the claim happened in the past? If so, what is it? 3. Explain how
it impacted Earths surface, atmosphere, climate, and life. 4. Could
this claim happen in Earths future? Complete the graphic Organizer.
Be prepared to discuss in Class!
Slide 9
Reading for Information PURPOSE: 1. To look at the claims of
possible causes of mass extinctions in Earths past, and to see if
there is any scientific evidence to support them. 2. To see how
mass extinctions impacted Earths surface, atmosphere, climate, and
life.
Slide 10
Jig-sawing Activity Directions Read the slip of the claim your
table group has been assigned and discuss it. 1. Identify how
scientists think your claim caused a mass extinction. 2. Explain
how it impacted Earths surface, atmosphere, climate, and life. 3.
Identify if there is any evidence to support your claim. If there
is evidence, what is it? 4. Could this claim happen in Earths
future? Be prepared to explain to the class NOT reading for slip of
paper!
Slide 11
What did we learn? Complete the graphic organizer as each table
group shares what they learned about their claim. By the end of
reporting out, you should know ~ what the different claims to mass
extinctions in Earths past are, and what evidence supports them if
any exists.
Slide 12
Brain Pop: Mass Extinctions
Slide 13
Reflection Based on our discussion of possible causes of mass
extinctions, can you explain how Earths surface, atmosphere,
climate and life were impacted, and support each one with
evidence.
Slide 14
Journal Entry #8- Could there be another mass extinction on our
planeta 6 th Mass Extinction??? What do you think and why? What
would be and why? What would be the cause if one occurred? the
cause if one occurred?
Slide 15
Could there be another mass extinction on our planet? Watch the
following video to see if your answer changes. What do you think?
http://www.youtube.com/watch?v=eY- ltUIsnrQ
http://www.youtube.com/watch?v=eY- ltUIsnrQ
