1. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu How to Use This Presentation To View the presentation as a slideshow with effects select “View” on the menu bar and click on “Slide Show.” To advance through the presentation, click the right-arrow key or the space bar. From the resources slide, click on any resource to see a presentation for that resource. From the Chapter menu screen click on any lesson to go directly to that lesson’s presentation. You may exit the slide show at any time by pressing the Esc key.

2. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter Presentation Transparencies Image and Math Focus Bank Bellringers Standardized Test Prep CNN Videos Visual Concepts Resources

3. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The History of Life on Earth Table of Contents Section 1 Evidence of the Past Section 2 Eras of the Geologic Time Scale Section 3 Humans and Other Primates Chapter 8

4. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Evidence of the Past Bellringer Imagine that you haven’t cleaned your room for thirty years. After 30 years, you finally decide to sort through the 2 m pile of stuff on your floor. What might you find on top of the pile? In the middle? on the bottom? Write your answer in your science journal. Chapter 8

5. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Evidence of the Past Objectives Explain how fossils can be formed and how their age can be estimated. Describe the geologic time scale and the way that scientists use it. Compare two ways that conditions for life on Earth have changed over time. Chapter 8

6. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Evidence of the Past Fossils Life Preserved in Rock Fossils are traces or imprints of living things—such as animals, plants, bacteria, and fungi— that are preserved in rock. Chapter 8

7. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Evidence of the Past The Age of Fossils Life Preserved in Rock Estimating the age of rocks and fossils based on its position in sedimentary rock is called relative dating. Absolute dating is a method that measures the age of fossils or rocks in years. The next slide shows how half-lives can be used to date fossils. Chapter 8

8. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Evidence of the Past Chapter 8

9. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Evidence of the Past The Geologic Time Scale The calendar scientists use to outline the history of life on Earth is called the geologic time scale. Divisions in Time Paleontologists have divided the geologic time scale into large blocks of time. Mass Extinctions Some of the important divisions in the geologic time scale mark times when rapid changes happened on Earth. During these times, many species died out completely, or became extinct. Chapter 8

10. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Evidence of the Past Chapter 8

11. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Evidence of the Past The Changing Earth Pangaea German scientist Alfred Wegener proposed that long ago the continents formed one landmass, which he called Pangaea, surrounded by a gigantic ocean. Do the Continents Move? In the mid-1960s, J. Tuzo Wilson of Canada came up with the idea that huge pieces of the Earth’s crust were pushed around by forces within the planet. Wilson’s theory of how these huge pieces of crust move around the Earth is called plate tectonics. Chapter 8

12. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Evidence of the Past Chapter 8

13. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Evidence of the Past The Changing Earth Adaptations to Slow Change When conditions on the Earth change, organisms may adapt or become extinct. A rapid change, such as a meteorite impact, may cause a mass extinction. But slow changes, such as moving continents, allow time for adaptation. Chapter 8

14. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Eras of the Geologic Time Scale Bellringer Suppose that electrical energy was never developed. How would your life differ from what it is like now? Write your answers in your science journal. Chapter 8

15. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Eras of the Geologic Time Scale Objectives Outline the major developments that allowed life to exist on Earth. Describe the types of organisms that arose during the four major divisions of the geologic time scale. Chapter 8

16. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Eras of the Geologic Time Scale Precambrian Time Precambrian time is the time from the formation of Earth 4.6 billion years ago to about 543 million years ago. How Did Life Begin? Scientists think that life developed from simple chemicals in the oceans and in the atmosphere. Energy from radiation and storms could have caused these chemical to react. Chapter 8

17. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Eras of the Geologic Time Scale Precambrian Time, continued Photosynthesis and Oxygen The first cyanobacteria began to release oxygen gas into the oceans and air. Eventually, some of the oxygen formed a new layer of gas in the upper atmosphere. Multicellular Organisms After about 1 billion years, organisms that were larger and more complex than prokaryotes appeared in the fossil record. Chapter 8

18. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Origin of Eukaryotic Cells Chapter 8 Click below to watch the Visual Concept. You may stop the video at any time by pressing the Esc key. Visual Concept Section 2 Eras of the Geologic Time Scale

19. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Eras of the Geologic Time Scale The Paleozoic Era The Paleozoic era began about 543 million years ago and ended about 248 million years ago. Life on Land During the 300 million years of the Paleozoic era, plants, fungi, and air-breathing animals slowly colonized land. Chapter 8

20. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Eras of the Geologic Time Scale The Mesozoic Era The Mesozoic era began about 248 million years ago and lasted about 183 million year. Life in the Mesozoic Era Dinosaurs are the most well known reptiles that evolved during the Mesozoic era. The Extinction of Dinosaurs At the end of the Mesozoic era, 65 million years ago, dinosaurs and many other animal and plant species became extinct. Chapter 8

21. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Eras of the Geologic Time Scale The Cenozoic Era The Cenozoic era began about 65 million years ago and continues today. The Age of Mammals The Cenozoic era is sometimes called the Age of Mammals. Mammals have dominated the Cenozoic era the way reptiles dominated the Mesozoic era. The Cenozoic Era Today We are currently living in the Cenozoic era. Modern humans appeared during this era. Chapter 8

22. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Eras of the Geologic Time Scale Chapter 8

23. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Humans and Other Primates Bellringer What makes you unique among your family members? What makes you recognizable as part of your family? Are all these traits physical or are some behavioral? Write your answer in your science journal. Chapter 8

24. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Humans and Other Primates Objectives Describe three characteristics that all primates share. Describe three major groups of hominids. Chapter 8

25. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Humans and Other Primates Primates Primates are a group of mammals that includes humans, apes, monkeys, and lemurs. The First Primates The ancestors of primates may have coexisted with the dinosaurs. Apes and Chimpanzees Scientists think that the chimpanzee, a type of ape, is the closest living relative of humans. Chapter 8

26. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Humans and Other Primates Primates, continued Hominids Humans are in a family separate from other primates. This family, called hominids, includes only humans and their human-like ancestors. The main characteristic that separates hominids from other primates is bipedalism. Bipedalism means “walking primarily upright on two feet.” Chapter 8

27. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Humans and Other Primates Chapter 8

28. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Humans and Other Primates Hominids Through Time The Earliest Hominids The earliest hominids had traits that were more humanlike than apelike. Australopithecines Many early hominids are classified as australopithecines. Their brains were slightly larger than the brains of apes. Chapter 8

29. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Humans and Other Primates Hominids Through Time, continued A Variety of Early Hominids Many australopithecines and other types of hominids lived at the same time. Some australopithecines had slender bodies and humanlike jaws and skulls. Scientists think that some of these types of hominids may have been the ancestors of modern humans. Global Hominids About 2.3 million years ago, a new group of hominids appeared. These new hominids were members of the group Homo, which includes modern humans. Chapter 8

30. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Humans and Other Primates Recent Hominids Neanderthals One recent hominid is known as Neanderthal. Neanderthals lived in Europe and western Asia. They hunted large animals, made fires, and wore clothing. About 30,000 years ago, Neanderthals disappeared. Early and Modern Humans Modern humans are classified as the species Homo sapiens. The earliest Homo sapiens existed in Africa 100,000 to 150,000 years ago. Of all known hominids, only Homo sapiens still exists. Chapter 8

31. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Humans and Other Primates Recent Hominids Drawing the Hominid Family Tree Human evolution was once thought to be a line of descent from ancient primates to modern humans. But scientists now speak of a “ tree” or even a “ bush” to describe the evolution of various hominids in the fossil record. Chapter 8

32. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The History of Life on Earth Use the terms below to complete the concept map on the next slide. Chapter 8 Concept Map geologic time scale mammals Mesozoic paleontologists eukaryotes relative dating absolute dating Paleozoic dinosaurs Precambrian

33. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Concept Map Chapter 8

34. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Concept Map Chapter 8

35. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu End of Chapter 8 Show

36. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation Read each of the passages. Then, answer the questions that follow each passage. Chapter 8 Reading

37. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation Passage 1 In 1995, paleontologist Paul Sereno and his team were working in an unexplored region of Morocco when they made an incredible find—an enormous dinosaur skull! The skull measured about 1.6 m in length, which is about the height of a refrigerator. Given the size of the skull, Sereno concluded that the skeleton of the entire animal must have been about 14 m long—about as big as a school bus, and even larger than Tyrannosaurus rex. Continued on the next slide Chapter 8

38. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation Passage 1, continued This 90-million-year-old predator most likely chased other dinosaurs by running on large, powerful hind legs, and its bladelike teeth meant certain death for its prey. Sereno named his new discovery Carcharodontosaurus saharicus, which means “shark-toothed reptile from the Sahara.” Continued on the next slide Chapter 8

39. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation 1. Paul Sereno estimated the total size of this Carcharodontosaurus based on A the size of Tyrannosaurus rex. B the fact that it was a predator. C the fact that it had bladelike teeth. D the fact that its skull was 1.6 m long. Chapter 8

40. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation 1. Paul Sereno estimated the total size of this Carcharodontosaurus based on A the size of Tyrannosaurus rex. B the fact that it was a predator. C the fact that it had bladelike teeth. D the fact that its skull was 1.6 m long. Chapter 8

41. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation 2. Which of the following is evidence that the Carcharodontosaurus was a predator? F It had bladelike teeth. G It had a large skeleton. H It was found with the bones of a smaller animal nearby. I It is 90 million years old. Chapter 8

42. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation 2. Which of the following is evidence that the Carcharodontosaurus was a predator? F It had bladelike teeth. G It had a large skeleton. H It was found with the bones of a smaller animal nearby. I It is 90 million years old. Chapter 8

43. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation 3. Which of the following is a fact in the passage? A Carcharodontosaurus was the largest predator that ever existed. B Carcharodontosaurus had bladelike teeth. C Carcharodontosaurus was as large as Tyrannosaurus rex. D Carcharodontosaurus was a shark-like reptile. Chapter 8

44. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation 3. Which of the following is a fact in the passage? A Carcharodontosaurus was the largest predator that ever existed. B Carcharodontosaurus had bladelike teeth. C Carcharodontosaurus was as large as Tyrannosaurus rex. D Carcharodontosaurus was a shark-like reptile. Chapter 8

45. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation Passage 2 In 1912, Alfred Wegener proposed a hypothesis called continental drift. At the time, many scientists laughed at his idea. Yet Wegener’s idea jolted the very foundations of geology. Wegener used rock, fossil, and glacial evidence from opposite sides of the Atlantic Ocean to support the idea that continents can “drift.” For example, Wegener recognized similar rocks and rock structures in the Appalachian Mountains and the Scottish Highlands, as well as similarities between rock layers in South Africa and Brazil. Continued on the next slide Chapter 8

46. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation Passage 2, continued He thought that these striking similarities could be explained only if these geologic features were once part of the same continent. Wegener proposed that because continents are less dense, they float on top of the denser rock of the ocean floor. Although continental drift explained many of Wegener’s observations, he could not find evidence to explain exactly how continents move. But by the 1960s, this evidence was found and continental drift was well understood. However, Wegener’s contributions went unrecognized until years after his death. Chapter 8

47. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation 1. Which of the following did Wegener use as evidence to support his hypothesis? A similarities between nearby rock layers B similarities between rock layers in different parts of the world C a hypothesis that continents float D an explanation of how continents move Chapter 8

48. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation 1. Which of the following did Wegener use as evidence to support his hypothesis? A similarities between nearby rock layers B similarities between rock layers in different parts of the world C a hypothesis that continents float D an explanation of how continents move Chapter 8

49. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation 2. Which of the following statements is supported by the above passage? F A hypothesis is never proven. G A new hypothesis may take many years to be accepted by scientists. H The hypothesis of continental drift was not supported by evidence. I Wegener’s hypothesis was proven wrong. Chapter 8

50. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation 2. Which of the following statements is supported by the above passage? F A hypothesis is never proven. G A new hypothesis may take many years to be accepted by scientists. H The hypothesis of continental drift was not supported by evidence. I Wegener’s hypothesis was proven wrong. Chapter 8

51. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation The map below shows the areas where fossils of certain organisms have been found. Use the map below to answer the questions that follow. Chapter 8 Interpreting Graphics

52. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation 1. Mesosaurus was a small, aquatic reptile and Glossopteris was an ancient plant species. What do these two have in common? A Their fossils have been found on several continents. B Their fossils are found in exactly the same places. C Their fossils have been found only in North America. D Their fossils have only been found near oceans. Chapter 8

53. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation 1. Mesosaurus was a small, aquatic reptile and Glossopteris was an ancient plant species. What do these two have in common? A Their fossils have been found on several continents. B Their fossils are found in exactly the same places. C Their fossils have been found only in North America. D Their fossils have only been found near oceans. Chapter 8

54. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation Chapter 8

55. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation 2. Which of the following statements is best supported by these findings? F All of the continents were once connected to each other. G South America was once connected to Africa. H Glossopteris is adapted to life at the South Pole. I Mesosaurus could swim. Chapter 8

56. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation 2. Which of the following statements is best supported by these findings? F All of the continents were once connected to each other. G South America was once connected to Africa. H Glossopteris is adapted to life at the South Pole. I Mesosaurus could swim. Chapter 8

57. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation Chapter 8

58. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation 3. The map provides evidence that the following continents were once connected to each other, with the exception of A North America. B Africa. C Antarctica. D South America. Chapter 8

59. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation 3. The map provides evidence that the following continents were once connected to each other, with the exception of A North America. B Africa. C Antarctica. D South America. Chapter 8

60. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation Read each question, and choose the best answer. Chapter 8 Math

61. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation 1. Four students are sharing a birthday cake. The first student takes half of the cake. The second student take half of what remains of the cake. Then, the third student takes half of what remains of the cake. What fraction of the cake is left for the fourth student? A 1/2 B 1/4 C 1/8 D 1/16 Chapter 8

62. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation 1. Four students are sharing a birthday cake. The first student takes half of the cake. The second student take half of what remains of the cake. Then, the third student takes half of what remains of the cake. What fraction of the cake is left for the fourth student? A 1/2 B 1/4 C 1/8 D 1/16 Chapter 8

63. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation 2. One sixteenth is equal to what percentage? F 6.25% G 12.5% H 25% I 50% Chapter 8

64. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation 2. One sixteenth is equal to what percentage? F 6.25% G 12.5% H 25% I 50% Chapter 8

65. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation 3. What is one-half of one-fourth? A 1/2 B 1/4 C 1/8 D 1/16 Chapter 8

66. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation 3. What is one-half of one-fourth? A 1/2 B 1/4 C 1/8 D 1/16 Chapter 8

67. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation 4. Half-life is the time it takes for one-half of the radioactive atoms in a rock sample to decay, or change into different atoms. Carbon-14 is a radioactive isotope with a half-life of 5,730 years. In a sample that is 11,460 years old, what percentage of carbon-14 from the original sample would remain? F 100% G 50% H 25% I 12.5% Chapter 8

68. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation 4. Half-life is the time it takes for one-half of the radioactive atoms in a rock sample to decay, or change into different atoms. Carbon-14 is a radioactive isotope with a half-life of 5,730 years. In a sample that is 11,460 years old, what percentage of carbon-14 from the original sample would remain? F 100% G 50% H 25% I 12.5% Chapter 8

69. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation 5. If a sample contains an isotope with a half-life of 10,000 years, how old would the sample be if 1/8 of the original isotope remained in the sample? A 5,000 years B 10,000 years C 20,000 years D 30,000 years Chapter 8

70. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation 5. If a sample contains an isotope with a half-life of 10,000 years, how old would the sample be if 1/8 of the original isotope remained in the sample? A 5,000 years B 10,000 years C 20,000 years D 30,000 years Chapter 8

71. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Evidence of the Past Chapter 8

72. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Evidence of the Past Chapter 8

73. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Evidence of the Past Chapter 8

74. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Evidence of the Past Chapter 8

75. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Eras of the Geologic Time Scale Chapter 8

76. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Humans and Other Primates Chapter 8

77. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation Chapter 8

78. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Eras of the Geologic Time Scale Chapter 8

79. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu CNN Videos Creating Digital Dinos Creating Digital Dinos Ice Age Discoveries Ice Age Discoveries Chapter 3 Protecting New Mexico's Petroglyphs Protecting New Mexico's Petroglyphs