2. The Mesozoic Era
Began approximately 245 million years ago
after a major mass extinction.
Is subdivided into 3 periods:
Triassic
Jurassic
Cretaceous
Ends about 66 million years ago with a
major mass extinction
4. Dinosaurs Myths
All dinosaurs are the same
Everything that is big and extinct is a
dinosaur
All dinosaurs lived at the same time
All ‘dinosaurs’ are extinct…
...you’ll see!
5. The Triassic Period
245 - 206 million years ago
Immediately after the Permian Mass
Extinction
Lots of new area is open for animals to live
Three general types of animals:
holdovers from before the extinction
new groups that lasted only a short time
new groups that lasted a long time
8. Two Groups of Dinosaurs
Ornithischian
Hips were similar to modern bird hips
Carnivorous short-necked
Herbivorous, long-necked
Saurischian
Hips were similar to reptile hips
Herbivorous with grinding-teeth
Herbivorous without grinding-teeth
10. The Jurassic Period
206 - 144 Million Years Ago
Giant plant-eating dinosaurs
Vicious carnivore dinosaurs
Oceans full of fish, squid, sharks, etc.
Ichthyosaurs and Plesiosaurs
Pterosaurs
Birds
12. Jurassic Plant Eating Dinosaurs
Many different forms
Many had ‘armor’ to
protect themselves
Triceratops
Ankylosaurus
Many very large
(larger than a
Rhino/Hippo)
Some were extremely
large (as long as a city
block): Diplodocus
Triceratops
14. Jurassic Carnivorous Dinosaurs
Many different forms
Some were very large:
Tyrannosaurus Rex
Allasaurus
Some were smaller:
Raptors, and many
more
All had sharp teeth,
claws, and speed
15. Jurassic Marine Dinosaurs
Most with similar
shapes as a dolphins
or sharks
Ate fish and other
marine animals
Some were VERY
large
All could swim VERY
fast
Ichthyosaurus
18. Jurassic Birds(?) - Archaeopteryx
Not a Pterosaur
Jaws and bone structure like
dinosaurs
Bones are hollow, like birds
Feathers
Was this an evolutionary
link between dinosaurs and
birds?
19. The Cretaceous Period
144 - 66 million years ago
The last period when Dinosaurs lived
Ends with a mass extinction around 66
million years ago
First flowering plants!
21. Cretaceous Plants
First plants with
flowers
Their appearance was
very rapid
They appeared at the
same time as the
number of insects
increased…
Could insects have
helped the flowering
plants evolve?
22. The Cretaceous Mass Extinction
Approximately 60% of all species went
extinct.
Affected many land animals/plants
Affected fewer marine animals
23. What organisms went extinct?
All dinosaurs
All pterosaurs
All ichthyosaurs
Many terrestrial plants
Many marine animals
24. What organisms survived?
MAMMALS (!)
Birds
Many plants (ferns were the most successful
plant for a while)
Trees with flowers
Small lizards/crocodiles/alligators/turtles
Fish, squids, sharks, etc.
25. What caused the extinction?
Meteorite impact theory
66 million years ago, a ~10 km wide meteorite
struck the Earth near what is now Mexico.
27. How could a meteorite impact
cause a mass extinction?
The impact caused shock waves, tidal waves, and
sent a tremendous amount of dust into the
atmosphere
As the dust re-entered the Earth’s atmosphere, it
would have instantly heated the atmosphere
causing tremendous forest fires
The dust could have caused the Earth’s climate to
cool in the long-run by blocking sunlight
Plants, animals, etc went extinct due to the climate
changes and competition between organisms
28. Meteorite Impact Evidence #1
Unique Quartz Crystals
Very commonly formed under high
pressure/temperature
This quarts was only found in meteorite
craters and nuclear testing sites
29. Meteorite Impact Evidence #2
Iridium
An element that is very rare in Earth
rocks and very common in meteorites
The layer of rocks above the last dinosaur
bones contains ~160 times ‘normal’
levels of iridium
30. Problems with the Meteorite
Impact Hypothesis
Why were some animals affected, while
others were not?
Why did birds survive, and dinosaurs (a very
close relative) not?
Why did small reptiles survive when small
dinosaurs didn’t?
Why did mammals survive?
31. Out-dated Hypotheses
Hay Fever - caused by flowering plants
Dinosaurs were so big, that they crushed
themselves
Mammals out-competed the dinosaurs
Mammals ate all the dinosaur eggs
Cosmic rays killed the dinosaurs
