Chapter Presentation

1. Resources Bellringers Chapter Presentation Transparencies Standardized Test Prep Image and Math Focus Bank CNN Videos Visual Concepts

2. Chapter 8 Section1 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.

3. Chapter 8 Section1 Evidence of the Past Fossils • Life Preserved in RockFossils are traces or imprints of living things—such as animals, plants, bacteria, and fungi—that are preserved in rock.

4. Chapter 8 Section1 Evidence of the Past The Age of Fossils • Life Preserved in RockEstimating 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.

5. Chapter 8 Section1 Evidence of the Past

6. Chapter 8 Section1 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 ExtinctionsSome 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.

7. Chapter 8 Section1 Evidence of the Past

8. Chapter 8 Section1 Evidence of the Past The Changing Earth • PangaeaGerman 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.

9. Chapter 8 Section1 Evidence of the Past

10. Chapter 8 Section1 Evidence of the Past The Changing Earth • Adaptations to Slow ChangeWhen 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.

11. Section2 Eras of the Geologic Time Scale Chapter 8 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.

12. Section2 Eras of the Geologic Time Scale Chapter 8 Precambrian Time • Precambrian timeis 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.

13. Section2 Eras of the Geologic Time Scale Chapter 8 Precambrian Time, continued • Photosynthesis and OxygenThe 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 OrganismsAfter about 1 billion years, organisms that were larger and more complex than prokaryotes appeared in the fossil record.

14. Section2 Eras of the Geologic Time Scale Chapter 8 Origin of Eukaryotic Cells Click below to watch the Visual Concept. You may stop the video at any time by pressing the Esc key. Visual Concept

15. Section2 Eras of the Geologic Time Scale Chapter 8 The Paleozoic Era • The Paleozoic era began about 543 million years ago and ended about 248 million years ago. • Life on LandDuring the 300 million years of the Paleozoic era, plants, fungi, and air-breathing animals slowly colonized land.

16. Section2 Eras of the Geologic Time Scale Chapter 8 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 DinosaursAt the end of the Mesozoic era, 65 million years ago, dinosaurs and many other animal and plant species became extinct.

17. Section2 Eras of the Geologic Time Scale Chapter 8 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 TodayWe are currently living in the Cenozoic era. Modern humans appeared during this era.

18. Section2 Eras of the Geologic Time Scale Chapter 8

19. Section3 Humans and Other Primates Chapter 8 Objectives • Describethree characteristics that all primates share. • Describe three major groups of hominids.

20. Section3 Humans and Other Primates Chapter 8 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 ChimpanzeesScientists think that the chimpanzee, a type of ape, is the closest living relative of humans.

21. Section3 Humans and Other Primates Chapter 8 Primates, continued • HominidsHumans 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.”

22. Section3 Humans and Other Primates Chapter 8

23. Section3 Humans and Other Primates Chapter 8 Hominids Through Time • The Earliest HominidsThe earliest hominids had traits that were more humanlike than apelike. • AustralopithecinesMany early hominids are classified as australopithecines. Their brains were slightly larger than the brains of apes.

24. Section3 Humans and Other Primates Chapter 8 Hominids Through Time, continued • A Variety of Early HominidsMany 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 HominidsAbout 2.3 million years ago, a new group of hominids appeared. These new hominids were members of the group Homo, which includes modern humans.

25. Section3 Humans and Other Primates Chapter 8 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 HumansModern 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.

26. Section3 Humans and Other Primates Chapter 8 Recent Hominids • Drawing the Hominid Family TreeHuman 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.

27. Chapter 8 The History of Life on Earth Concept Map Use the terms below to complete the concept map on the next slide.

28. Chapter 8 Concept Map

29. Chapter 8 Concept Map

30. End of Chapter 8 Show

31. Chapter 8 Section1 Evidence of the Past

32. Chapter 8 Section1 Evidence of the Past

33. Chapter 8 Section1 Evidence of the Past

34. Chapter 8 Section1 Evidence of the Past

35. Section2 Eras of the Geologic Time Scale Chapter 8

36. Section3 Humans and Other Primates Chapter 8

37. Chapter 8 Standardized Test Preparation

38. Section2 Eras of the Geologic Time Scale Chapter 8

39. Chapter 3 CNN Videos • Creating Digital Dinos • Ice Age Discoveries • Protecting New Mexico's Petroglyphs