1. When Dinosaurs Ruled the Earth
The Mesozoic Era
When Dinosaurs Ruled the Earth

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

3. Mesozoic Reptiles Turtles Crocodiles/Alligators Lizards
Ichthyosaurs (large marine reptiles)
Pterosaurs (large flying reptiles)
Dinosaurs (land dinosaurs)

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

6. The Triassic World

7. Triassic Plant Life Mosses Scale Trees (like palm trees)
Ginkos (my favorite)

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

9. Earliest Dinosaurs (Triassic)
Pisanosaurus
Length:3 feet Height:1 foot Weight:15 pounds
Eoraptor:
Length:3 feet Height:1 feet Weight:20 pounds
Lesothsaurus:
Length:3 feet Height:1 foot Weight:15 pounds

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

11. The Jurassic World

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

13. Ankyloasaurus
Diplodocus

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

16. Jurassic Pterosaurs Pterodactyls and Pterosaurs
Most had trouble ‘walking’
Were very good flyers
Had hollow bones
Small (~ 1 foot) and very large (~ 16 feet)

17. More Pterodactyls

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!

20. The Cretaceous World

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.

26. Meteorite Impact
This is an EXAGGERATED view of a meteorite impact

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