17–1 The Fossil Record

2. 17–1 The Fossil Record A. Fossils and Ancient Life • The fossil record provides evidence about the history of life on earth. It also shows how different groups of organisms have changed over time

3. 17–1 The Fossil Record • How Fossils Form • Most fossils form in sedimentary rock. It is formed when exposure to rain, heat, wind and cold breaks down clay • As layers of sediment build up over time, dead organisms may also sink to the bottom and become buried • Conditions are right, the remains may be kept intact

4. 17–1 The Fossil Record C. Interpreting Fossil Evidence 1. Relative Dating- the age of a fossil is determined by comparing its placement with that of fossils in other layers of rock (estimate age of fossils) 2. Radioactive Dating- scientists calculate the age of a sample based on the amount of remaining radioactive isotopes it contains

5. 17–1 The Fossil Record D. Geologic Time Scale • Eras 2. Periods

6. Section 17-1 Age of fossil with respect to another rock or fossil (that is, older or younger) Age of a fossil in years Comparing depth of a fossil’s source stratum to the position of a reference fossil or rock Determining the relative amounts of a radioactive isotope and nonradioactive isotope in a specimen Imprecision and limitations of age data Difficulty of radio assay laboratory methods Compare/Contrast Table Comparing Relative and Absolute Dating of Fossils Relative Dating Absolute Dating Can determine Is performed by Drawbacks Go to Section:

7. Section 17-1 Figure 17-2 Formation of a Fossil Water carries small rock particles to lakes and seas. Dead organisms are buried by layers of sediment, which forms new rock. The preserved remains may later be discovered and studied. Go to Section:

8. Figure 17-5 Geologic Time Scale Section 17-1 (millions of years ago) (millions of years ago) Era Period Time (millions of years ago) Era Period Time Era Period Time Permian Carboniferous Devonian Silurian Ordovician Cambrian 290 – 245 363–290 410–363 440–410 505–440 544–505 Quarternary Tertiary Cretaceous Jurassic Triassic 1.8–present 65–1.8 145–65 208–145 245–208 Vendian 650–544 Go to Section:

9. Figure 17-5 Geologic Time Scale Figure 17-5 Geologic Time Scale Section 17-1 (millions of years ago) (millions of years ago) Era Period Time (millions of years ago) Era Period Time Era Period Time Permian Carboniferous Devonian Silurian Ordovician Cambrian 290 – 245 363–290 410–363 440–410 505–440 544–505 Quarternary Tertiary Cretaceous Jurassic Triassic 1.8–present 65–1.8 145–65 208–145 245–208 Vendian 650–544

10. Figure 17-5 Geologic Time Scale Section 17-1 (millions of years ago) (millions of years ago) Era Period Time (millions of years ago) Era Period Time Era Period Time Permian Carboniferous Devonian Silurian Ordovician Cambrian 290 – 245 363–290 410–363 440–410 505–440 544–505 Quarternary Tertiary Cretaceous Jurassic Triassic 1.8–present 65–1.8 145–65 208–145 245–208 Vendian 650–544

11. 17–2 Earth’s Early History A. Formation of Earth • Earth’s early atmosphere probably contained hydrogen cyanide, carbon dioxide, carbon monoxide, nitrogen, hydrogen sulfide, and water

12. 17–2 Earth’s Early History • The First Organic Molecules • Organic molecules would have been able to be constructed but the oxygen in atmosphere was to reactive and would destroy any organic molecules that formed

13. 17–2 Earth’s Early History C. How Did Life Begin? 1. Formation of Microspheres- protection that allowed for the growth of organic molecules 2. Evolution of RNA and DNA- still unanswered but scientists are searching

14. 17–2 Earth’s Early History • Free Oxygen • The rise of oxygen in the atmosphere drove some life forms to extinction, while other life forms evolved new, more efficient metabolic pathways that used oxygen for respiration

15. 17–2 Earth’s Early History • Origin of Eukaryotic Cells • The endosymbiotic theory proposes that eukaryotic cells arose from living communities formed by prokaryotic organisms

16. Figure 17-12 Endosymbiotic Theory Chloroplast Plants and plantlike protists Aerobic bacteria Ancient Prokaryotes Photosynthetic bacteria Nuclear envelope evolving Mitochondrion Primitive Photosynthetic Eukaryote Animals, fungi, and non-plantlike protists Primitive Aerobic Eukaryote Ancient Anaerobic Prokaryote Go to Section:

17. 17–2 Earth’s Early History F. Sexual Reproduction and Multicellularity • A few hundred million years after the evolution of sexual reproduction, evolving life forms crossed to developing multicellular organisms from single celled (unicellular) organisms

18. 17–3 Evolution of Multicellular Life • Precambrian Time- life existed only in the sea B. Paleozoic Era- rich with evidence of many types of marine life • Mesozoic Era- increasing dominance of dinosaurs, appearance of flowering plants D. Cenozoic Era- mammals evolved adaptations that allowed them to live in various environments, on land, water and air

19. Geologic Time Scale with Key Events Section 17-3 (millions of years ago) Era Period Time Key Events Cenozoic Mesozoic Paleozoic Precambrian Time Quaternary Tertiary Cretaceous Jurassic Triassic Permian Carboniferous Devonian Silurian Ordovician Cambrian 1.8–present 65–1.8 145–65 208–145 245–208 290–245 363–290 410–363 440–410 505–440 544–505 650–544 Glaciations; mammals increased; humans Mammals diversified; grasses Aquatic reptiles diversified; flowering plants; mass extinction Dinosaurs diversified; birds Dinosaurs; small mammals; cone-bearing plants Reptiles diversified; seed plants; mass extinction Reptiles; winged insects diversified; coal swamps Fishes diversified; land vertebrates (primitive amphibians) Land plants; land animals (arthropods) Aquatic arthropods; mollusks; vertebrates (jawless fishes) Marine invertebrates diversified; most animal phyla evolved Anaerobic, then photosynthetic prokaryotes; eukaryotes, then multicellular life

20. 17–4 Patterns of Evolution A. Mass Extinctions- dinosaurs B. Adaptive Radiation- species evolved into several different forms that live in different ways C. Convergent Evolution- unrelated organisms come to resemble one another

21. 17–4 Patterns of Evolution D. Coevolution- process by which two species evolve in response to changes in each other over time E. Punctuated Equilibrium- patterns of long, stable periods interrupted by brief periods of more rapid change Gradualism- patterns of slow, gradual change

22. 17–4 Patterns of Evolution F. Developmental Genes and Body Plans- changes in developmental genes, revealing major news about evolution of life

23. Unrelated Related Intense environmental pressure Similar environments Inter-relationshiops Small populations Different environments Convergent evolution Punctuated equilibrium Adaptive radiation Coevolution Extinction Flowchart Species that are form in under under in in can undergo can undergo can undergo can undergo can undergo Go to Section:

24. Section 15-1 • A Trip Around the World • While on his voyage around the world aboard the H.M.S. Beagle, Charles Darwin spent about one month observing life on the Galápagos Islands. There, he encountered some unique animals, such as finches and tortoises.

25. 1. On a sheet of paper, list five animals that you have encountered in the past two days. • 2. How do these animals differ from the finches and tortoises of the Galápagos Islands? (Examine Figures 15–3 and 15–4 in your textbook.) • 3. Propose a hypothesis to account for the differences between the animals that you observed and the finches and tortoises of the Galápagos Islands.

26. 15–1 The Puzzle of Life’s Diversity Section 15-1 A. Voyage of the Beagle B. Darwin’s Observations 1. Patterns of Diversity 2. Living Organisms and Fossils 3. The Galápagos Islands C. The Journey Home

27. Giant Tortoises of the Galápagos Islands Pinta IslandIntermediate shell Hood Island Saddle-backed shell Pinta IslandIntermediate shell

28. Figure 15–1 Darwin’s Voyage

29. My, How You’ve Changed! • Prior to the 1800s, life scientists knew that living things changed over generations. They just didn’t know how these changes were brought about.

30. 1. Divide a sheet of paper into two columns and title the first one Inherited Characteristics. Title the second column Acquired Characteristics. In the first column, list the characteristics that you believe you have always had. For example, you may have brown eyes or curly hair.

31. 2. In the second column, list your acquired characteristics. For example, you may have learned how to play a musical instrument. 3. Which of the items in your lists do you think you might pass on to your children? Explain your answer

32. 15–2 Ideas That Shaped Darwin’s Thinking A. An Ancient, Changing Earth 1. Hutton’s Theory of Geological Change 2. Lyell’s Principles of Geology

33. 15–2 Ideas That Shaped Darwin’s Thinking B.Lamarck’s Theory of Evolution 1. Tendency Toward Perfection 2. Use and Disuse 3. Inheritance of Acquired Traits 4. Evaluating Lamarck’s Theory C.Population Growth

34. Hutton’s Theory of Geological Change • In 1975, geologist James Hutton proposed that layers of rock form very slowly. Some rocks are moved up by forces beneath the Earth’s surface, others are buried. Resulting rocks, mountains, and valleys are then shaped by a variety of natural forces-including rain, heat and cold temperatures

35. Lyell’s Principles of Geology • Lyell’s work explained how awesome geological features could be built up or torn down over long periods of time. • His work influenced Darwin in two ways: • If the earth could change overtime, might life change as well? • He realized that it must have taken many, many years, earth must be very old

36. Movement of Earth’s Crust As the surface erodes due to water, wind, waves, or glaciers, the older rock surface is exposed. When part of Earth’s crust is compressed, a bend in a rock forms, tilting the rock layers. New sediment is then deposited above the exposed older rock surface. Sedimentary rocks form in horizontal layers

37. Lamarck’s Theory of Evolution1. Tendency Toward Perfection • He proposed that all organisms are continually changing and acquiring features that help them live more successfully in their environment

38. 2. Use and Disuse • He proposed that organisms could alter the size or shape of particular organs by using their bodies in new ways. • Conversely, if a winged animal did not use its wings (ex. of disuse) the wings would decrease in size over generations and finally disappear

39. 3. Inheritance of Acquired Traits • Lamarck thought that acquired characteristics could be inherited • By this reasoning, if you spent much of your life lifting weights to build muscles, your children would inherit big muscles, too.

40. 4. Evaluating Lamarck’s Theory • He was incorrect in many ways • Lamarck, like Darwin, did not know how traits are inherited or that behavior has no effect on its inheritable characteristics • One of first to develop scientific theory of evolution and realize that organisms are adapted to their environment

41. Figure 15–7 Lamarck’s Theory of Evolution

42. 15–3 Darwin Presents His Case A. Publication of On theOrigin of Species • Darwin(1859)proposed a mechanism for evolution called natural selection • Continuous for millions of years and continues in all living things • Others strongly opposed

43. 15–3 Darwin Presents His Case B. Natural Variation and Artificial Selection • Natural variation is the differences among individuals of a species, is found in all types of organisms • Artificial Selection occurs through a technique called selective breeding, that would determine which individuals to use for breeding based on the natural variation that was found

44. 15–3 Darwin Presents His Case C.Evolution by Natural Selection • The Struggle for Existence- means that members of each species compete regularly to obtain food, living space, an other necessities of life

45. 15–3 Darwin Presents His Case C. Evolution by Natural Selection 2. Survival of the Fittest • Fitness- the ability of an individual to survive and reproduce in its specific environment • Adaptation- is any inherited characteristics that increase an organism’s chance of survival

46. 15–3 Darwin Presents His Case C. Evolution by Natural Selection 2. Survival of the Fittest • Individuals that are better suited to their environment-that is, with high levels of fitness-survive and reproduce most successfully

47. 15–3 Darwin Presents His Case C. Evolution by Natural Selection 2. Survival of the Fittest • Over time, natural selection results in changes in the inherited characteristics of a population. These changes increase a species’ fitness in it’s environment

48. 15–3 Darwin Presents His Case C. Evolution by Natural Selection • Descent With Modification • Each living species has descended, with changes, from other species over time

49. 15–3 Darwin Presents His Case D. Evidence of Evolution 1. The Fossil Record • provided evidence that living things have been evolving for millions of years. • Sometimes fossil records includes similar, intermediate forms of a group of organisms that together suggest gradual modification over time

50. The fossil record Geographic distribution of living species Homologous body structures Similaritiesin early development Physical remains of organisms Common ancestral species Similar genes Similar genes Evidence of Evolution includes which is composed of which indicates which implies which implies