Chapter 7: Concepts of Time

1. Chapter 7: Concepts of Time • 8-2.4 Recognize the relationship among the units – eon, era, period, and epoch – into which the geologic time scale is divided. • 8-2.5 Illustrate the vast diversity of life that has been present on Earth over time by using the geologic time scale.

2. Geologic Time EONS,ERAS, PERIODS, AND EPOCHS - The geologic time scale is a record of the life forms and geologic events in Earth’s history • Paleozoic era – Many animals w/o backbones lived during this time. Mesozoic era – The age of reptiles/dinosaurs Cenozoic era – The age of Mammals.

3. Geologic Time • Eons are divided into smaller units of time called Eras. • An Eon is about a Billion Years. • There have only been 4 Eons since Earth formed.

4. Geologic Time Periods • Eras are divided into smaller units of time called periods. Periods range in time from tens of millions of years to less than two million years. Epochs • Geologists further divide the Cenozoic era into smaller units of time called epochs.

6. True of False • Epoch are smaller than Periods. • Periods are smaller than Eras. • Eras are larger than Periods or Epochs.

7. Geologic Time – EARTH’S HISTORY Precambrian Time (4.6 billion- 544 million) Precambrian Earth - 4.6 billion y.a., Earth formed from a cloud of dust and gas - 100’s of millions of years  lava forms continents - Later the atmosphere forms  oceans

8. Geologic Time Precambrian Time (4.6 billion- 544 million) Precambrian Life - Fossils of single celled organisms as early as 3.5 billion y.a. - 2.5 billion y.a. 1st organisms use photosynthesis - O2 slowly increased - Sponges, worms, etc. evolved that used O2 to make energy from food

9. Which of these events did not happen during Precambrian Time? • Sponges appear • Single celled organisms live • Mammals appear • Single cell organisms use oxygen to make energy.

10. Geologic Time Paleozoic Era (544 million-245 million) Cambrian Explosion - Great # of different kinds of organisms evolved - Many had hard parts (shells, outer skeletons) ex. brachiopods and trilobites - All life lived in the sea

11. Geologic Time Paleozoic Era (544 million-245 million) Ordivician and Silurian Periods - Ancestors of modern squid/octopus appear - 1st vertebrates (jawless fish) - Simple land plants evolve - 1st insects and spiders appear (Silurian)

12. Geologic Time Paleozoic Era (544 million-245 million) Devonian Period - Age of fish - Early ferns - Fish now had jaws, bones, skeletons, scales - Sharks appear late Devonian - 1st vertebrates on land (lungfish) - Amphibians evolved ex. Ichtyostega - Swamp forests

13. Geologic Time Paleozoic Era (544 million-245 million) Carboniferous - Appalachian Mountains form - Small reptiles evolve - Winged insects, dragonflies, cockroaches evolve - Giant ferns and cone bearing plants - “Coal forests” were common

14. Geologic Time Paleozoic Era (544 million-245 million) Permian - Pangaea forms - Reptiles become dominant - Warm blooded reptiles appear Mass Extinction Ends Paleozoic - Climate changes due to Pangaea cause extinction - Plants and animals affected - 95 % of ocean life disappears (trilobites) - Many fish and reptiles survive

15. Which appeared during the Paleozoic Era? • First Vertebrates • Appalachian Mountains • Winged insects and roaches • All of the above

16. Geologic Time Mesozoic Era (245 million-65 million) - Fish, insects, reptiles and cone bearing plants had survived mass extinction - Age of Reptiles Triassic Period - 225 million y.a. 1st dinosaur Coelophysis - Small (mouse sized) mammals evolve from warm blooded reptiles - 1st turtles, crocodiles - Conifers, palm trees and ginkos dominant

17. Geologic Time Mesozoic Era (245 million-65 million) Jurassic Period - Dinosaurs become dominant - Some plant eaters, some meat eaters - Diplodocus, Stegosaurus, Dicraeosaurus (largest) - 1st flying reptiles appear Pterosaurs - Archaeopteryx (first bird) evolves

18. A Trip Through Geologic Time Mesozoic Era (245 million-65 million) Cretaceous Period - Dinosaurs/reptiles still dominant - Tyrannosaurus Rex - First snakes appear - Birds beat out flying reptiles for the skies - Flying reptiles  extinct - Turtles/crocodiles common in seas - Flowering plants evolve

19. Geologic Time Mesozoic Era (245 million-65 million) Another Mass Extinction - 65 million y.a. - Asteroid strikes Earth - Dust and gas block sunlight for years - Half of all plant/animal groups  extinct - Dinosaurs  extinct

20. Use your white boards to answer: Tyrannosaurus Rex lived during the __________ period of the Mesozoic Era.

21. Geologic Time Cenozoic Era (65 million- present day) - Dinosaur extinction made way for mammals to thrive - Age of mammals - Mammals evolve adaptations to live on land, in water, in air Tertiary Period - Earth’s climate warm, mild - Mollusks appear - Whales and dolphins evolve - Flowering plants, insects and mammals flourish - First grasses allow for early grazing mammals (ancestors of cattle, deer, sheep)

22. Geologic Time Cenozoic Era (65 million- present day) Tertiary Period - Early horses, elephants, bears, rodents, primates - Earliest human ancestors

23. Geologic Time Cenozoic Era (65 million- present day) Quartenary Period - Series of ice ages, climate cools - Continental glaciers cover much of North America and Europe - 20,000 y.a. climate begins to warm - Algae, coral, mollusks, fish and mammals thrive in oceans - Flowering plants, mammals including bats, cats, dogs, cattle and humans become common

24. A Trip Through Geologic Time Cenozoic Era (65 million- present day) Human Evolution - Earliest human ancestors 3.5 million y.a. - 100,000 y.a. Homo Sapiens evolve in Africa - 12,000 to 15,000 y.a. humans had moved to every continent but Antarctica

25. Use your card to answer: • Which of these does not belong in the Cenozoic Era? • Wooly Mammoth • Trilobites • Algae • Ice age

26. Using page 101Draw Time Scale in Notebook

27. Work Book pages 40-42 • Use text book pages 100-110