Warm Up 1/9/09

1. Warm Up 1/9/09 • What important event in animal evolution marks the beginning of the Cambrian? a. the ability to fly b. the ability to swim c. the appearance of fossils d. the appearance of hard parts • What event may have triggered the great Paleozoic extinction? a. climatic change b. heightened solar activity c. meteorite strike d. changes in Earth’s orbit • In the early Paleozoic, life was restricted (only in) to the ____. a. air c. continents b. seas d. islands Answers: 1) d. 2) a. 3) b.

2. Mesozoic Era: Age of Reptiles & Cenozoic Era: Age of Mammals Chapter 13, Sections 3 & 4

3. Mesozoic History • The Mesozoic era spanned about 183 million years, and it is divided into three periods: the Triassic, Jurassic, and Cretaceous • The Mesozoic era began with much of the world’s land above sea level (very few marine fossils are found in North America from the Triassic Period) • In the Cretaceous, shallow seas invaded much of western North America creating great swamps (leaving large coal deposits) • A major event of the Mesozoic era was the breakup of Pangaea • This process lasted for 200 million years, forming the Atlantic Ocean • It also caused the North American plate to override the Pacific plate, causing massive deformation, forming the Sierra Nevada and Rocky Mountains

4. The Breakup of Pangaea

5. Concept Check • Explain how the Atlantic Ocean was formed. • A rift developed during the breakup of a Pangaea that widened and eventually became the Atlantic Ocean.

6. Mesozoic Life • When the Mesozoic began, its life forms were the survivors of the great Paleozoic extinction • Gymnosperm – seed-bearing plant that bears its seeds on the surface of cones • Unlike the first plants to invade land, gymnosperms were not restricted to living near the water’s edge, and they could take advantage of nutrients and space available in drier areas • The gymnosperms quickly became the dominant plants of the Mesozoic • Gymnosperm trees included the cycads, the conifers, and the ginkgoes • Among the animals, reptiles readily adapted to the drier Mesozoic environment, being the first true land animals

7. Gymnosperms

8. Reptiles Dominate • With the perfection of the shelled egg, reptiles quickly became the dominant land animals • They continued this dominance for 160 million years • Dinosaur – land-dwelling reptile of the Mesozoic era • At the end of the Mesozoic, many reptile groups became extinct • Only a few types of reptiles survived to recent times (the turtles, snakes, crocodiles, and lizards) • Most scientists believe that the extinction of the large reptiles was caused by a large meteorite that collided with Earth

9. Reptile Evolution

10. Pteranodon—The Flying Reptile

11. Concept Check • How did reptiles become the dominant land animals? • The development of shelled eggs allowed dinosaurs and other reptiles to dominate the land.

13. Cenozoic Era • The Cenozoic era, or “era of recent life,” encompasses the past 65 million years of Earth history • It is during this span that the physical landscapes and life forms of our modern world came into being • The Cenozoic era is shorter than the other eras, but it possesses a rich history because of the completeness of the geological record improves as time approaches the present • The Cenozoic era is divided into two periods of very unequal duration, the Tertiary period (63 million years) and the Quaternary period (2 million years)

14. Cenozoic North America • Most of North America was above sea level throughout the Cenozoic era • The Atlantic and Gulf coastal regions were far removed from an active plate boundary, so they were tectonically stable • Plate interactions during the Cenozoic caused many events of mountain building, volcanism, and earthquakes in the West

15. Sierra Nevada Mountains

16. Topographic Relief Map of U.S.

17. Cenozoic Life • Mammals replaced reptiles as the dominant land animals • The Cenozoic is often called the “age of mammals” because land mammals came to dominate land life • It could also be called the “age of flowering plants” because angiosperms came to dominance • Angiosperms—flowering plants with covered seed—replaced gymnosperms as the dominant land plants • The advances in seed fertilization and dispersal allowed angiosperms to experience a development and expansion as the Mesozoic came to a close • Development of flowering plants strongly influenced the evolution of birds and mammals

18. Angiosperms

19. Mammals Replace Reptiles • Back in the Mesozoic, an important evolutionary event was the appearance of primitive mammals in the late Triassic, about the same time that the dinosaurs evolved • Because mammals are warm-blooded, they could survive in cold regions and search for food during any season or time of day; they also adapted insulating body hair and more efficient lungs and hearts • These adaptations allow mammals to lead more active lives than reptiles • Their development and specialization took 4 principal directions: (1) increase in size, (2) increase in brain capacity, (3) specialization of teeth to fit certain diets, (4) specialization of limbs to particular environments

20. La Brea Tar Pits

21. Concept Check • What adaptations caused mammals to be successful? • Mammals are warm-blooded, so they could survive in cold regions. They also have developed insulating body hair and more efficient hearts and lungs.

22. Large Mammals and Extinction • Some groups of mammals became very large • Many large forms of mammals were common as recently as 11,000 years ago; however, a wave of late Pleistocene extinctions rapidly eliminated these animals from the landscape • In North America, the mastodon and mammoth, both huge relatives of the elephant became extinct; as well as saber-toothed cats, giant beavers, large ground sloths, horses, camels, giant bison, and some others • Some scientists believe that early humans hurried the decline of these animals by selectively hunting large forms

23. Large Mammals

24. Assignment • Read Chapter 13, Sections 3 & 4 (pg. 377-385) • Do Chapter 13 Assessment #1-26 (pg. 389-390) • For Section 3: Do #’s 3, 6, 7, 14, 19, 25 • For Section 4: Do #’s 1, 8-10, 18, 26 • Study for the Chapter 13 Quiz!!!