The document summarizes several theories for the mass extinction of dinosaurs at the end of the Cretaceous period, approximately 66 million years ago. The most widely accepted theory is that a large meteor struck the Yucatan Peninsula, causing global climate changes like cooling temperatures and acid rain that dinosaurs could not adapt to. Additionally, massive volcanic eruptions in India also contributed to changing the climate and releasing greenhouse gases. Diseases carried by insects may have also weakened dinosaur populations. The mass extinction was likely caused by a combination of these catastrophic events occurring simultaneously.

1. What They Didn’t
Tell You
The Mass Extinction of Dinosaurs
Randi Leigh Thomas

2. Origins
• The rise of the dinosaurs was not an
overnight sensation.
• Dinosaurs took about 50 million years to
develop into the species we recognize
today.
• Unlike the images from Jurassic Park, not
all of the dinosaurs lived in one climate or
time period.

3. Popular Extinction Theories
-Cosmic radiation from a nearby exploding
supernova star killed them.
-Acid rain from volcano activity was
responsible.
-Continental drift altered the climate.
-Disease ravaged dinosaur populations.
-Small mammals appeared that fed on
dinosaur eggs.

4. Most Widely Accepted Theories
• Baptistina: The Meteor Meltdown
• Deccan Traps: The Indian Volcanoes
• Resistance Issues: Bugs and Illness
• The Double Whammy: A Catastrophic Series

6. Meteor Meltdown

7. • In the 1980s, Luis and Walter Alvarez
discovered Iridium in the K-T boundary.
• Iridium is rare on Earth but abundant in
meteors.
• The duo theorized that a gigantic meteor or
comet struck the Earth at the end of the
Cretaceous era causing many deathly events
to ensue.

8. • The impact caused:
-A massive explosion
-Dust cloud formation
-No visible light
-Massive forest fires
-Smoke in the atmosphere
-A general cooling of the planet
• There is an observable crater along the
Mexican Yucatan Peninsula that coincides with
the K-T Boundary.

9. • The asteroid was imagined to be 6 to 12 miles in diameter causing a
crater 130 miles across.
• The Southwest Research Institute has named it “Baptistina” and
traced the meteors path:
-160 million years ago a 100 mile wide asteroid was headed for
the planet.
-A smaller and unnamed asteroid struck and shattered Baptistina
sending fragments toward the atmosphere.
-95 million years later, the fragments reached Earth destroying
the dinosaurs.

11. Volcanoes and Greenhouse Gases

12. • The Deccan Traps are an active lava bed in
India.
• These volcanoes were extremely active over a
long period of time but the most massive
eruption coincides with the K-T Boundary.
• Those eruptions could have released 10 times
as many harmful gases into the atmosphere as
the meteor crash.

13. • These substances include:
-Extreme quantities of dust
-Sulphuric Acid
-Carbon Dioxide
• Leading to the extreme temperature swing at the end of the
Mesozoic.
• The existing 2/3 of these lava beds covered
almost a million square kilometers. That’s
about half of India!

15. Dinosaur Disease

16. • Because of the climate of the late Cretaceous,
insects were able to flourish.
• Many of the bugs from that era were
preserved in amber and that has allowed
scientists to exam them for diseases.
• It was determined that some of the smallest
animals we know today could have taken
down giants.

17. • Some bugs carried leishmania and malaria
that could easily infect reptiles.
• Fossilized dung revealed the ingestion of
nematodes, trematodes, and protozoa that
could have caused dysentery.
• These diseases were relatively new so the
dinosaurs had little resistance to these pests.

18. Catastrophic Coupling

19. • The mass extinction of the dinosaurs is not the
only one to have happened in history.
• A bigger extinction occurred 250 million years
ago known as “The Great Dying”, or the
Permian-Triassic.
• It eliminated 90% of known species from the
face of the Earth.

20. • Scientists observed periods of time when
there were asteroid impacts, volcanic
eruptions, or neither happening.
• The results showed that there were more
deaths when both impacts and eruptions
happened.
• This led them to believe that a large scale
chain of events was the most probable cause
for the end of the dinosaurs.

22. Other Possibilities
It is also highly suggested that around the time
of the K-T boundary, dinosaurs were already in
decline.
• The herbivores main food source, vegetation, was dying
off because of reduced oxygen levels and higher
temperatures.
• As herbivores died, carnivores followed suit without
nutrition.
• There was already a sharp decline in dinosaur population
and it is proposed that perhaps the asteroid just finished
them off.

23. Can We Bring Them Back?

24. Iconic movies like Jurassic Park have always
made us wonder whether bringing back
dinosaurs is possible. In theory, it is. But here’s
why it would never work:
• The habitat dinosaurs lived in is destroyed. A national park
just isn’t big enough for 4 or 5 large carnivores!
• Finding a suitable host for the DNA would be almost
impossible. Yes, birds are dinosaurs too. But I don’t foresee
them hatching raptors any time soon.
• Do we really want T-Rex marching through our backyards?

25. • If we could find perfectly preserved dinosaur
DNA, extract and sequence it with little error,
organize it into chromosomes, place it into the
living egg of the correct species (wait...that
would mean we already had the egg and its
own DNA!), and raise the egg successfully,
then we could all have pet Triceratops. Yeah,
right.
• Visit this website:
http://www.ucmp.berkeley.edu/diapsids/buzz/p
opular.html

26. Please watch this video in your own time!
“Jurrassic Park: How it Should Have Ended”
http://youtu.be/xQrRg3LtjXY

27. Keep in Mind…
• Not all dinosaurs are extinct!
Take a look at birds.
• Theories of how the dinosaurs
disappeared are still disputed. There’s not
many proven facts on the subject yet.
• And last but certainly not least:
Dinosaurs are cool whether you’re 4 or 40.