1. Eras of Earth’s History
EQ: What causes changes in the Earth? How does knowing the past give us a VISION for the future?

2. Precambrian Time Eon

3. Precambrian Time Eon 4.6 billion years ago-545 million years ago
Information about this time on Earth is SCARCE
Rocks are buried deep within Earth’s Crust
Information on rocks damaged or destroyed by Earth’s inner heat and pressure of other rock layers
Moon forms during this time

4. Precambrian Eon continued….
Earth originally thought to be “dead”
Volcanoes produce toxic atmosphere
Water and water Vapor that form the oceans comes from volcanoes, asteroids and comets!!!

5. *Precambrian Eon continued….*
Closer look at rocks show Signs of cynobacteria
Cynobacteria-changed Earth’s past atmosphere of water vapor, ammonia and methane into Nitrogen and Oxygen: STILL FOUND ALIVE TODAY in deep sea Thermal Vents and in volcanoes
Today’s atmosphere made up of nitrogen , oxygen and water vapor

6. Phanerozoic Eon (3 Eras) *Paleozoic Era: 545-245m.y.a.: Basic Traits*
The longest of all the Eras on the Earth
Contains 7 periods
Fossils of large organisms first found in this era
Almost all are marine environment
Largest land Continent called Gondwana (begins with 90 % of Earth’s surface covered by water)
Warm Earth; Life limited to oceans; ozone layer not fully developed: no plants on land intially
Ends with the largest mass extinction in Earth’s history (90% of all life killed)

7. *Why did life first start in the ocean?*
More stable environment: Water 22x heat capacity than air
UV Protection:
DNA Damaged by UV radiation
DNA contains all information for life
Earth’s ozone layer just starting to develop from oxygen produced by cynobacteria

8. *Why did life first start in the ocean?*
Gravity’s affect neutralized
-organisms would develop in environment in which gravity would have no impact on animal’s structure
NO need for powerful muscles to move

9. *Why did life first start in the ocean?*
Easier to obtain minerals and gases necessary for life
Water naturally has these items dissolved in it
Organisms could just absorb materials as water passed by

10. *Easier to obtain food*
Food would be suspended in 3 dimensions: filter feeding or feeding with tentacles become popular

11. 7 periods of Paleozoic Era
Cambrian Period ( )
Trilobites
Clams
Inland seas suggest warm Earth
Land Formation: supercontinent Gondwana; (S hemisphere)

12. Ordovician Period (505-438) First land plants (ferns)
First vertebrates: early fish appear
Life moves into shallower water: Suggests ozone layer almost fully developed as life moves closer to land
Laurussia seperates from Gondwana

13. Silurian Period (438-408) Corals Dominate World’s Oceans Warm Earth
Plants move further inland
Animals now moving further inland by way of water; fresh water fish
N. America covered by shallow sea

14. *Devonian Period (408-360)* Fish dominate oceans First amphibians
Signs of Earth beginning to cool: Water retreats forcing organisms to adapt to the new changes. More land created

15. Mississippian Period (360-320)
Amphibians dominate land life
Earth much cooler as glaciers move southward from polar regions
Cooler Earth forces Amphibians to adapt to changes; (less water-thicker skin)

16. Pennsylvanian Period (320-286)
First reptiles and insects
Shallow seas over N.America almost disappeared
Cooler Earth

17. *Permian Period (286-245)* Glaciers retreat Earth Warming back up
Ends with largest mass extinction in fossil record (Asteroid impact)

18. *Mesozoic Era * AGE OF DINOSAURS 245-65 Million Years Ago
Split into 3 major periods
Triassic period ( million years)
Jurassic Period ( million years)
Cretaceous Period ( million years)

19. Triassic Period Marks beginning of Mesozoic Era
First dinosaurs and mammals appeared around 225 million years ago
Atlantic Ocean
Pangaea breaks up
Flowering Plants appear
Eoraptor, Plateosaurus and Teratosaurus

20. *Why Dinosaurs Evolve*
Environmental Factors- As Pangaea break apart each land mass gets a unique climate
Disease Influence- Diseases possible reason species die out
Competition for Food- organisms compete for same food sources; winners live losers die
Predatory Influence- animals develop defenses against Predators

21. Jurassic Period (208-144) Flowering Plants and Dinosaurs dominate land
Birds appear
Appalachian Mountains Form
Dinosaurs become more diverse from basic shapes
Allosaurus
Stegosaurus
Diplodicus
Ceratosaurus

22. Cretaceous Period (144-65)
Most advanced dinosaurs: Highly specialized, most successful of all dinosaur species
Modern Earth Appears
Ends in Mass Extinction of Dinosaurs
Tyrannosaurs, Tricerotops, Ankylosaurus, Protocerotype, Velocoraptors, Pterodactyl

23. Comparison of the Dinosaurs
Triassic
Jurassic
Cretaceous
small
(Stegosaurus)
Med- large
T-rex, Triceraptops, Raptors
Largest
Cold blooded
Warm blooded
Reptile-like
More Advanced
Most Advanced/ Bird like in many ways
Simple body plans
4 legs herbivores
2 legs carnivores
Defenses against Preadtors
Most advanced features
Hollow bones (t rex, raptors)
Proto-feathers on skin
Each continent had its own unique Dinosaurs

24. *Meteorite Theory?*
Says that asteroid/comet 3-5 miles wide struck near Yucatan Peninsula and caused Dinosaur Extinction
Iridium deposits in KT layer help support this
However, closest Dinosaur bones ever found date about 1,000 prior to event
Climate Change/Disease reason for extinction??

25. *Cenozoic Era* Continents were drifting apart—present time of Earth
African plate collided with European plate creating the Alps
India slammed into Asian plate creating Himalayas
Climate was cooled causing several “ice ages”

26. *Mammals Survive because*
Small size easier to maintain body temperature in climate change
Ability to Hibernate during an extreme event
Mothers provide food for young from milk, No other organisms do this (mammals unique)

27. Cenozoic Era
Age of Mammals (65mya- present day)
2 Periods

28. Tertiary Period (65mya – 1.6mya)
Earth’s climate was warm and mild
Ocean mammals like dolphins and whales evolve
Land-insects, flowering plants and mammals, birds dominate
Mega mammals mammals evolve
Alps and Himalayas Form

29. Quaternary Period: (1.6 mya- today)
Mega mammals die out/ (Climate Change?)
Present period
Humans appear—100,000 years ago
Grand Canyon forms
Last ice age 15,000-10,000 years ago