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How to Use This Presentation
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Standardized Test Prep
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Chapter 9 Table of Contents Section 1 Geologic Time
A View of Earth’s Past Table of Contents Section 1 Geologic Time Section 2 Precambrian Time and the Paleozoic Era Section 3 The Mesozoic and Cenozoic Eras

Chapter 9 Section 1 Geologic Time Objectives Summarize how scientists worked together to develop the geologic column. List the major divisions of geologic time.

Chapter 9 The Geologic Column Section 1 Geologic Time
geologic column an ordered arrangement of rock layers that is based on the relative ages of the rocks and in which the oldest rocks are at the bottom. Evidence of changing conditions on Earth’s surface is recorded in the rock layers of Earth’s crust. The geologic time scale outlines the development of Earth and of life on Earth. No single area on Earth contained a record of all geologic time, so scientists combined observations to create a standard geologic column.

The Geologic Column, continued
Chapter 9 Section 1 Geologic Time The Geologic Column, continued Rock layers in a geologic column are distinguished by the types of rock the layers are made of and by the kinds of fossils the layers contain. Fossils in the upper layers resemble modern plants and animals. Many of the fossils discovered in old layers are from species that have been extinct for millions of years.

Chapter 9 Section 1 Geologic Time The Geologic Column, continued Reading Check Where would you find fossils of extinct animals on a geologic column?

Chapter 9 Section 1 Geologic Time The Geologic Column, continued Reading Check Where would you find fossils of extinct animals on a geologic column? You would find fossils of extinct animals in older layers of a geologic column.

Chapter 9 Section 1 Geologic Time The Geologic Column, continued Using a Geologic Column Scientists use geologic columns to estimate the age of rock layers that cannot be dated radiometrically. To determine the layer’s age, scientists compare a given rock layer with a similar layer in a geologic column that contains the same fossils or that has the same relative position. If the two layers match, they likely formed at about the same time.

Divisions of Geologic Time
Chapter 9 Section 1 Geologic Time Divisions of Geologic Time The geologic history of Earth is marked by major changes in Earth’s surface, climate, and types of organisms. Geologists use these indicators to divide the geologic time scale into smaller units. Rocks grouped within each unit contain similar fossils and each unit is generally characterized by fossils of a dominant life-form.

Divisions of Geologic Time, continued
Chapter 9 Section 1 Geologic Time Divisions of Geologic Time, continued

Chapter 9 Section 1 Geologic Time Divisions of Geologic Time, continued Eons and Eras The largest unit of geologic unit of time is an eon. Geologic time is divided into four eons: the Hadean eon, the Archean eon, the Proterozoic eon, and the Phanerozoic eon. The first three eons are part of a time interval commonly known as Precambrian Time. This 4 billion year interval contains most of Earth’s history.

Chapter 9 Section 1 Geologic Time Divisions of Geologic Time, continued Eons and Eras era a unit of geologic time that includes two or more periods After Precambrian time the Phanerozoic eon began. This eon is divided into smaller units of geologic time called eras. The first era of the Phanerozoic eon was the Paleozoic Era, which lasted 292 million years.

Chapter 9 Section 1 Geologic Time Divisions of Geologic Time, continued Eons and Eras Paleozoic rocks contain fossils of a wide variety of marine and terrestrial life forms. After the Paleozoic Era the Mesozoic Era began and lasted about 183 million years. Mesozoic fossils include early forms of birds and reptiles. The present era is the Cenozoic Era, which began 65 million years ago. Fossils of mammals are common in Cenozoic rocks.

Chapter 9 Section 1 Geologic Time Divisions of Geologic Time, continued Eons and Eras period a unit of geologic time that is longer than an epoch but shorter than an era epoch a subdivision of geologic time that is longer than an age but shorter than a period. Eras are divided into shorter time units called periods. Each period is characterized by specific fossils and is usually named for the location in which the fossils were first discovered.

Chapter 9 Section 1 Geologic Time Divisions of Geologic Time, continued Eons and Eras Where the rock record is most complete and least deformed, a detailed fossil record may allow scientists to divide period into shorter time units called epochs. Epochs may be divided into smaller units of time called ages. Ages are defined by the occurrence of distinct fossils in the fossil record.

Chapter 9 Earth-History Clock Section 1 Geologic Time
Click below to watch the Visual Concept. Visual Concept

Section 2 Precambrian Time and the Paleozoic Era
Chapter 9 Objectives Summarize how evolution is related to geologic change. Identify two characteristics of Precambrian rock. Identify one major geologic and two major biological developments during the Paleozoic Era.

Section 2 Precambrian Time and the Paleozoic Era
Chapter 9 Evolution evolution an inheritable change in the characteristics within a population from one generation to the next; the development of new types of organisms from preexisting types of organisms over time By examining rock layers and fossils, scientists have discovered evidence that species of livings things have changed over time. Scientists call this process evolution.

Chapter 9 Evolution, continued Evolution and Geologic Change
Section 2 Precambrian Time and the Paleozoic Era Chapter 9 Evolution, continued Evolution and Geologic Change Scientists think that evolution occurs by means of natural selection. Evidence for evolution included the similarity in skeletal structures of animals. Major geologic and climatic changes can affect the ability of some organisms to survive. By using geologic evidence, scientists try to determine how environmental changes affected organisms in the past.

Chapter 9 Evolution, continued
Section 2 Precambrian Time and the Paleozoic Era Chapter 9 Evolution, continued

Chapter 9 Evolution, continued
Section 2 Precambrian Time and the Paleozoic Era Chapter 9 Evolution, continued Click below to watch the Visual Concept. Visual Concept

Chapter 9 Precambrian Time
Section 2 Precambrian Time and the Paleozoic Era Chapter 9 Precambrian Time Precambrian time the interval of time in the geologic time scale from Earth’s formation to the beginning of the Paleozoic era, from 4.6 billion to 542 million years ago. The time interval that began with the formation of Earth and ended about 542 million years ago is known as Precambrian time, which makes up 88% of Earth’s history.

Precambrian Time, continued
Section 2 Precambrian Time and the Paleozoic Era Chapter 9 Precambrian Time, continued

Section 2 Precambrian Time and the Paleozoic Era Chapter 9 Precambrian Time, continued The Precambrian rock record is difficult to interpret, therefore we do not know much about what happened during that time. Most Precambrian rocks have been so severely deformed and altered by tectonic activity that the original order of rock layers is rarely identifiable.

Section 2 Precambrian Time and the Paleozoic Era Chapter 9 Precambrian Time, continued Precambrian Rocks Large areas of exposed Precambrian rocks, called shields, exist on every continent. Nearly half of the valuable mineral deposits in the world occur in the rocks of Precambrian shields. These valuable minerals include nickel, iron, gold, and copper.

Section 2 Precambrian Time and the Paleozoic Era Chapter 9 Precambrian Time, continued Precambrian Life Fossils are rare in Precambrian rocks mostly because Precambrian life-forms lacked bones, or other hard parts that commonly form fossils. One of the few Precambrian fossils that have been discovered are stromatolites. The presence of stromatolite fossils in Precambrian rocks indicates that shallow seas covered much of Earth during that time.

Chapter 9 The Paleozoic Era
Section 2 Precambrian Time and the Paleozoic Era Chapter 9 The Paleozoic Era Paleozoic Era the geologic era that followed Precambrian time and that lasted from 542 million to 251 million years ago. Paleozoic rocks hold an abundant fossil record. The number of plant and animal species on Earth increased dramatically at the beginning of the Paleozoic Era. Because of this rich fossil record, the Paleozoic Era has been divided into seven periods.

The Paleozoic Era, continued
Section 2 Precambrian Time and the Paleozoic Era Chapter 9 The Paleozoic Era, continued The Cambrian Period The Cambrian Period is the first period of the Paleozoic Era. Marine invertebrates thrived in the warm waters that existed during this time. The most common of the Cambrian invertebrates were trilobites. Scientists use many trilobites as index fossils to date rocks to the Cambrian Period.

Section 2 Precambrian Time and the Paleozoic Era Chapter 9 The Paleozoic Era, continued The Cambrian Period The second most common animals of the Cambrian Period were the brachiopods, a group of shelled animals. Fossils indicated that at least 15 different families of brachiopods existed during this period. Other common Cambrian invertebrates include worms, jellyfish, snails, and sponges.

Section 2 Precambrian Time and the Paleozoic Era Chapter 9 The Paleozoic Era, continued Reading Check Name three common invertebrates from the Cambrian Period.

Section 2 Precambrian Time and the Paleozoic Era Chapter 9 The Paleozoic Era, continued Reading Check Name three common invertebrates from the Cambrian Period. Your answer should include three of the following: brachiopods, trilobites, jellyfish, worms, snails, and sponges.

Section 2 Precambrian Time and the Paleozoic Era Chapter 9 The Paleozoic Era, continued The Ordovician Period During this period, populations of trilobites began to shrink, and clamlike brachiopods and cephalopod mollusks became the dominant invertebrate life-form. Colonies of graptolites also flourished in the oceans, and the first vertebrates appeared. The most primitive vertebrates were fish, which did not have jaws or teeth and were covered with thick, bony plates.

Section 2 Precambrian Time and the Paleozoic Era Chapter 9 The Paleozoic Era, continued The Silurian Period During the Silurian Period, echinoderms, relatives of modern sea stars, and corals became more common. Scorpion-like sea creatures called eurypterids also existed during this period. Near the end of this period, the earliest land plants as well as animals evolved on land.

Section 2 Precambrian Time and the Paleozoic Era Chapter 9 The Paleozoic Era, continued The Devonian Period The Devonian Period is called the Age of Fishes because fossils of many bony fishes were discovered in rocks of this period. On type of fish, called a lungfish, had the ability to breathe air. Another type of fish, Rhipidistians, were air-breathing fish that had strong fins that may have allowed them to crawl onto the land for short periods of time. Land plants, such as giant horsetails, ferns, and cone-bearing plants also began to develop during this period.

Section 2 Precambrian Time and the Paleozoic Era Chapter 9 The Paleozoic Era, continued The Carboniferous Period In North America, the Carbiniferous Period is divided into the Mississippian and Pennsylvanian Periods. During this time, the climate was warm, and forests and swamps covered most of the world. Amphibians and fish continued to flourish, and the first vertebrates that were adapted to live on land appeared.

Section 2 Precambrian Time and the Paleozoic Era Chapter 9 The Paleozoic Era, continued The Permian Period The Permian Period marks the end of the Paleozoic Era, because a mass extinction of a several life-forms occurred at the end of this period. During this time, the continents had joined to form Pangaea, and as a result, the seas that covered the world retreated. As the seas retreated, several species of marine life became extinct. But, reptiles and amphibians survived the environmental changes.

Section 3 The Mesozoic and Cenozoic Eras
Chapter 9 Objectives List the periods of the Mesozoic and Cenozoic Eras. Identify two major geologic and biological developments during the Mesozoic Era. Identify two major geologic and biological developments during the Cenozoic Era.

Chapter 9 The Mesozoic Era
Section 3 The Mesozoic and Cenozoic Eras Chapter 9 The Mesozoic Era mass extinction an episode during which large numbers of species become extinct Mesozoic Era the geologic era that lasted from 251 million to 65.5 million years ago; also called the Age of Reptiles. Earth’s surface changed dramatically during the Mesozoic Era. Pangaea broke into smaller continents, and the climate was warm and humid. Lizards, turtles, snakes and dinosaurs flourished during this era.

The Mesozoic Era, continued
Section 3 The Mesozoic and Cenozoic Eras Chapter 9 The Mesozoic Era, continued

Section 3 The Mesozoic and Cenozoic Eras Chapter 9 The Mesozoic Era, continued The Triassic Period The Mesozoic Era is known as the Age of Reptiles and is divided into three periods: the Triassic, the Jurassic, and the Cretaceous Periods. The Triassic period marked the appearance of dinosaurs. Most dinosaurs were about 4 m to 5 m long and moved very quickly. Reptiles called ichthyosaurs lived in the oceans. The ammonite, a marine invertebrate, was dominant, and serves as a Mesozoic index fossil.

Section 3 The Mesozoic and Cenozoic Eras Chapter 9 The Mesozoic Era, continued The Jurassic Period Two major groups of dinosaurs evolved during the Jurassic Period: the saurischians, or “lizard-hipped” dinosaurs, and the ornithischians, or “bird-hipped” dinosaurs. Brontosauruses, now called Apatosauruses were saurischians. Stegosauruses and Pterosaurs were ornithischians.

Section 3 The Mesozoic and Cenozoic Eras Chapter 9 The Mesozoic Era, continued Reading Check Name two fossils that were discovered in the fossil record of the Jurassic Period.

Section 3 The Mesozoic and Cenozoic Eras Chapter 9 The Mesozoic Era, continued Reading Check Name two fossils that were discovered in the fossil record of the Jurassic Period. Your answer could include any two of the following: Archaeopteryx, pterosaurs, Apatosaurus, and Stegosaurus

Section 3 The Mesozoic and Cenozoic Eras Chapter 9 The Mesozoic Era, continued The Cretaceous Period Among the common Cretaceous dinosaurs were the Tyrannosaurus Rex, the ankylosaurs, the ceratopsians, and the hadrosaurs. The earliest flowering plants, or angiosperms, appeared during this period. The most common of these plants were magnolias and willows. Later, trees such as maples, oaks, and walnuts became abundant.

Section 3 The Mesozoic and Cenozoic Eras Chapter 9 The Mesozoic Era, continued The Cretaceous-Tertiary Mass Extinction The Cretaceous Period ended in another mass extinction. No dinosaur fossils have been found in rocks that formed after the Cretaceous Period. Many scientists accept the impact hypothesis as the explanation for the extinction of the dinosaurs. This hypothesis is that about 65 million years ago, a giant meteorite crashed into Earth. The impact of the collision raised enough dust to block the sun’s rays for many years, resulting in a colder climate that caused plant life to die and many animal species to become extinct.

Chapter 9 Mass Extinction Section 3 The Mesozoic and Cenozoic Eras
Click below to watch the Visual Concept. Visual Concept

Chapter 9 The Cenozoic Era Section 3 The Mesozoic and Cenozoic Eras
Cenozoic Era the current geologic era, which began 65.5 million years ago; also called the Age of Mammals During the Cenozoic Era, dramatic changes in climate have occurred. As temperatures decreased during the ice ages, new species that were adapted to life in cooler climates appeared. Mammals became the dominant life-form and underwent many changes. The Cenozoic Era is divided into two periods: the Tertiary Period and the Quaternary Period.

The Cenozoic Era, continued
Section 3 The Mesozoic and Cenozoic Eras Chapter 9 The Cenozoic Era, continued The Quaternary and Tertiary Periods The Tertiary Period includes the time before the last ice age, and is divided into five epochs: The Paleocene, Eocene, Oligocene, Miocene, and Pliocene Epochs. The Quaternary Period began with the last ice age and includes the present. The Quaternary is divided into two epochs: The Pleistocene and Holocene Epochs.

Section 3 The Mesozoic and Cenozoic Eras Chapter 9 The Cenozoic Era, continued The Paleocene and Eocene Epochs The fossil record indicates that during the Paleocene Epoch many new mammals, such as small rodents, evolved. Other mammals, including the earliest known ancestor of the horse, first whales, flying squirrels, and bats, evolved during this time. Worldwide, temperatures dropped by about 4ºC at the end of the Eocene Epoch.

Section 3 The Mesozoic and Cenozoic Eras Chapter 9 The Cenozoic Era, continued The Oligocene and Miocene Epochs During these epochs, the worldwide climate became significantly cooler and drier. The modern Antarctic icecap began to form. The Mediterranean Sea dried up and refilled several times. This climate change caused many early mammals to become extinct. However large species of deer, pigs, horses, camels, cats, and dogs flourished. Also, the climate change favored grasses, cone-bearing, and hardwood trees.

Section 3 The Mesozoic and Cenozoic Eras Chapter 9 The Cenozoic Era, continued The Pliocene Epoch During the Pliocene Epoch, animals such as bears, dogs, and cats, evolved into modern forms. Herbivores, such as the giant ground sloth, flourished. Dramatic climatic changes occurred, and the continental ice sheets began to spread. The Bering land bridge and the Central American land bridge formed, allowing various species to migrate between the continents.

Section 3 The Mesozoic and Cenozoic Eras Chapter 9 The Cenozoic Era, continued Reading Check Why did sea level fall in the Pliocene Epoch?

Section 3 The Mesozoic and Cenozoic Eras Chapter 9 The Cenozoic Era, continued Reading Check Why did sea level fall in the Pliocene Epoch? During the ice ages, water from the ocean was frozen as ice, so the amount of liquid water in the seas decreased and sea level fell.

Section 3 The Mesozoic and Cenozoic Eras Chapter 9 The Cenozoic Era, continued The Pleistocene Epoch During the Pleistocene Epoch, ice sheets in Europe and North America advanced and retreated several times. Some animals had certain features that allowed them to survive the cold climate, such as the thick fur that covered woolly mammoths. Other species survived by moving to warmer regions, while some species eventually became extinct.

Section 3 The Mesozoic and Cenozoic Eras Chapter 9 The Cenozoic Era, continued The Pleistocene Epoch Fossils of the earliest ancestors of modern humans were discovered in Pleistocene sediments. Evidence of more-modern human ancestors indicated that early humans may have been hunters.

Section 3 The Mesozoic and Cenozoic Eras Chapter 9 The Cenozoic Era, continued The Holocene Epoch The Holocene Epoch began as the last glacial period ended. As the ice sheets melted, sea level rose about 140 m, and the coastlines took on their present shapes. Modern humans developed agriculture and began to make and use tools made of bronze and iron.

Chapter 9 A View of Earth’s Past Brain Food Video Quiz

Chapter 9 Maps in Action Fossil Evidence for Gondwanaland

Chapter 9 Multiple Choice
Standardized Test Prep Multiple Choice 1. Dinosaurs first became the dominant life-forms during which geologic period? A. Quaternary Period B. Jurassic Period C. Triassic Period D. Cretaceous Period

Multiple Choice, continued
Chapter 9 Standardized Test Prep Multiple Choice, continued 1. Dinosaurs first became the dominant life-forms during which geologic period? A. Quaternary Period B. Jurassic Period C. Triassic Period D. Cretaceous Period

Chapter 9 Standardized Test Prep Multiple Choice, continued 2. Pangaea broke into separate continents during F. the Paleozoic Era. G. the Mesozoic Era. H. the Cenozoic Era. I. Precambrian time.

Chapter 9 Standardized Test Prep Multiple Choice, continued 3. Why are fossils rarely found in Precambrian rock? A. Most Precambrian organisms did not have hard body parts that commonly form fossils. B. Precambrian rock is buried too deeply for geologists to study it. C. Most Precambrian organisms were too small to leave fossil remains. D. Precambrian rock is made of a material that prevented the formation of fossils.

Chapter 9 Standardized Test Prep Multiple Choice, continued 4. Which of the following statements describes a principle of natural selection? F. The environment has more than enough resources to support all of the individuals that are born in a given ecosystem. G. Only individuals well-suited to the environment are likely to survive and reproduce. H. Individuals in a healthy population are identical and have the same traits. I. Most species produce plentiful offspring that will all live until maturity and reproduce.

Chapter 9 Short Response
Standardized Test Prep Short Response 5. What is the term for the largest unit of geologic time?

Short Response, continued
Chapter 9 Standardized Test Prep Short Response, continued 5. What is the term for the largest unit of geologic time? An era

Chapter 9 Standardized Test Prep Short Response, continued 6. What is the term for the gradual development of organism from other organisms by means of natural selection?

Chapter 9 Standardized Test Prep Short Response, continued 6. What is the term for the gradual development of organism from other organisms by means of natural selection? evolution

Chapter 9 Standardized Test Prep Short Response, continued 7. Why is the Cenozoic Era also known as the Age of the Mammals?

Chapter 9 Standardized Test Prep Short Response, continued 7. Why is the Cenozoic Era also known as the Age of the Mammals? Mammals became the dominant life-forms and underwent many evolutionary changes during this era.

The Discovery of a Dinosaur
Chapter 9 Standardized Test Prep Reading Skills Read the passage below. Then, answer questions 8–11. The Discovery of a Dinosaur In 1995, paleontologist Paul Sereno was working in a previously unexplored region of Morocco when his team made an astounding discovery - an enormous dinosaur skull. The skill was nearly 1.6 m long. Given the size of the skull, Sereno concluded that the skeleton of the animal that it came from must have been about 14 m long - about as long as a full-sized school bus. The dinosaur was even larger than the Tyrannosaurus rex. The newly discovered dinosaur was thought to be 90 million years old. It most likely chased other dinosaurs by running on large, powerful hind legs, and its bladelike teeth must have meant certain death for its prey.

Reading Skills, continued
Chapter 9 Standardized Test Prep Reading Skills, continued 8. Which of the following is evidence that the dinosaur described in the passage above was most likely a predator? A. It had sharp, bladelike teeth. B. It had a large skeleton and powerful hind legs used for running. C. It was found next to the bones of a smaller animal. D. It was more than 90 million years old.

Chapter 9 Standardized Test Prep Reading Skills, continued 9. What types of information do you think that fossilized teeth provide about an organism? F. the color of its skin G. the types of food it ate H. the speed at which it ran I. the mating habits it had

Chapter 9 Standardized Test Prep Reading Skills, continued 10. According to the passage, which of the following statements is true? A. This dinosaur was most likely a predator. B. This skull belonged to a large Tyrannosaurus rex. C. This dinosaur had powerful arms. D. This dinosaur ate mainly plants and berries.

Chapter 9 Standardized Test Prep Reading Skills, continued 11. What are some methods that scientist might have used to determine that the age of the dinosaur skull was 90 million years old?

Chapter 9 Standardized Test Prep Reading Skills, continued 11. What are some methods that scientist might have used to determine that the age of the dinosaur skull was 90 million years old? Your answer should include the following points: an understanding that scientists not only can, but usually do, use multiple means of authentication when dating the remains of ancient plants and animals. Scientists could use carbon dating to determine the skull’s age; scientists could also use nearby index fossils and stratigraphic layers to further support their carbon dating results.

Interpreting Graphics
Chapter 9 Standardized Test Prep Interpreting Graphics Use the figure below to answer questions The timeline shows the time divisions of the Mesozoic and Cenozoic eras.

Interpreting Graphics, continued
Chapter 9 Standardized Test Prep Interpreting Graphics, continued 12. Human civilization developed during which of the following periods of time? A. Triassic Period B. Jurassic Period C. Tertiary Period D. Quaternary Period

Chapter 9 Standardized Test Prep Interpreting Graphics, continued 13. If Earth formed about 4.6 billion years ago, what percentage of Earth’s total history did the Cenozoic period fill? F. About 1.5 % G. About 10.5% H. About 15% I. About 50%

Chapter 9 Standardized Test Prep Interpreting Graphics, continued 14. Which event coincides with the start of the Cenozoic Era?

Chapter 9 Standardized Test Prep Interpreting Graphics, continued 14. Which event coincides with the start of the Cenozoic Era? The mass extinction of the dinosaurs.

Chapter 9 Standardized Test Prep Interpreting Graphics, continued The graph below shows data on global temperature changes during the last millennium. Use this graph to answer question 15.

Chapter 9 Standardized Test Prep Interpreting Graphics, continued 15. How do you think the temperature changes during the Little Ice Age of the Middle Ages affected the freezing and thawing of global waters? Explain your answer.

Chapter 9 Standardized Test Prep Interpreting Graphics, continued 15. How do you think the temperature changes during the Little Ice Age of the Middle Ages affected the freezing and thawing of global waters? Explain your answer. During the Little Ice Age, glaciers did not increase in size by very much, but local freezing dates came earlier and thawing dates came later.

The Geologic Time Scale
Chapter 9 The Geologic Time Scale

Similar Skeletal Structures of Mammals
Chapter 9 Similar Skeletal Structures of Mammals

Precambrian Time and the Paleozoic Era
Chapter 9 Precambrian Time and the Paleozoic Era

The Mesozoic and Cenozoic Eras
Chapter 9 The Mesozoic and Cenozoic Eras

Fossil Evidence for Gondwanaland
Chapter 9 Fossil Evidence for Gondwanaland

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