Eras of Earth’s History

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 (545-505) • 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 (245-208 million years) • Jurassic Period (208-144 million years) • Cretaceous Period (144-65 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

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