Warm UpWarm Up1) During which era did the supercontinent Pangaea

began to break up?

a. Cenozoic c. Paleozoic

b. Precambrian d. Mesozoic

2) What animals dominated the Mesozoic Era?

a. fish c. mammals

b. dinosaurs d. amphibians What likely contributed to the extinction that marks

the end of the Mesozoic Era?

a. changes in Earth’s orbit c. an ice age

b. global warming d. a meteorite collision

Answers: 1) d. 2) b. 3) d.

Cenozoic Era:Cenozoic Era:Age of MammalsAge of Mammals

Chapter 13, Section 4Chapter 13, Section 4

Cenozoic EraCenozoic Era The Cenozoic era, or “era of recent life,” The Cenozoic era, or “era of recent life,”

encompasses the past 65 million years of Earth encompasses the past 65 million years of Earth historyhistory

It is during this span that the physical It is during this span that the physical landscapes and life forms of our modern world landscapes and life forms of our modern world came into beingcame into being

The Cenozoic era is shorter than the other eras, The Cenozoic era is shorter than the other eras, but it possesses a rich history because of the but it possesses a rich history because of the completeness of the geological record improves completeness of the geological record improves as time approaches the presentas time approaches the present

The Cenozoic era is divided into two periods of The Cenozoic era is divided into two periods of very unequal duration, the Tertiary period (63 very unequal duration, the Tertiary period (63 million years) and the Quaternary period (2 million years) and the Quaternary period (2 million years)million years)

Cenozoic North AmericaCenozoic North America

Most of North America was above sea Most of North America was above sea level throughout the Cenozoic eralevel throughout the Cenozoic era

The Atlantic and Gulf coastal regions were The Atlantic and Gulf coastal regions were far removed from an active plate far removed from an active plate boundary, so they were tectonically stableboundary, so they were tectonically stable

Plate interactions during the Cenozoic Plate interactions during the Cenozoic caused many events of mountain building, caused many events of mountain building, volcanism, and earthquakes in the Westvolcanism, and earthquakes in the West

Sierra Nevada MountainsSierra Nevada Mountains

Topographic Relief Map of U.S.Topographic Relief Map of U.S.

Cenozoic LifeCenozoic Life MammalsMammals replaced reptiles as the dominant land replaced reptiles as the dominant land

animalsanimals The Cenozoic is often called the “age of mammals” The Cenozoic is often called the “age of mammals”

because land mammals came to dominate land lifebecause land mammals came to dominate land life It could also be called the “age of flowering plants” It could also be called the “age of flowering plants”

because angiosperms came to dominancebecause angiosperms came to dominance AngiospermsAngiosperms—flowering plants with covered seed—flowering plants with covered seed

—replaced gymnosperms as the dominant land —replaced gymnosperms as the dominant land plantsplants

The advances in seed fertilization and dispersal The advances in seed fertilization and dispersal allowed angiosperms to experience a development allowed angiosperms to experience a development and expansion as the Mesozoic came to a closeand expansion as the Mesozoic came to a close

Development of flowering plants strongly influenced Development of flowering plants strongly influenced the evolution of birds and mammalsthe evolution of birds and mammals

AngiospermsAngiosperms

Mammals Replace ReptilesMammals Replace Reptiles Back in the Mesozoic, an important evolutionary event Back in the Mesozoic, an important evolutionary event

was the appearance of primitive mammals in the late was the appearance of primitive mammals in the late Triassic, about the same time that the dinosaurs Triassic, about the same time that the dinosaurs evolvedevolved

Because mammals are warm-blooded, they could Because mammals are warm-blooded, they could survive in cold regions and search for food during any survive in cold regions and search for food during any season or time of day; they also adapted insulating season or time of day; they also adapted insulating body hair and more efficient lungs and heartsbody hair and more efficient lungs and hearts

These adaptations allow mammals to lead more active These adaptations allow mammals to lead more active lives than reptileslives than reptiles

Their development and specialization took 4 principal Their development and specialization took 4 principal directions: (1) increase in size, (2) increase in brain directions: (1) increase in size, (2) increase in brain capacity, (3) specialization of teeth to fit certain diets, capacity, (3) specialization of teeth to fit certain diets, (4) specialization of limbs to particular environments(4) specialization of limbs to particular environments

La Brea Tar PitsLa Brea Tar Pits

Concept CheckConcept Check

What adaptations caused mammals to be What adaptations caused mammals to be successful?successful?

Mammals are warm-blooded, so they Mammals are warm-blooded, so they could survive in cold regions. They also could survive in cold regions. They also have developed insulating body hair and have developed insulating body hair and more efficient hearts and lungs.more efficient hearts and lungs.

Large Mammals and ExtinctionLarge Mammals and Extinction Some groups of mammals became very largeSome groups of mammals became very large Many large forms of mammals were common as Many large forms of mammals were common as

recently as 11,000 years ago; however, a wave recently as 11,000 years ago; however, a wave of late Pleistocene extinctions rapidly eliminated of late Pleistocene extinctions rapidly eliminated these animals from the landscapethese animals from the landscape

In North America, the mastodon and mammoth, In North America, the mastodon and mammoth, both huge relatives of the elephant became both huge relatives of the elephant became extinct; as well as saber-toothed cats, giant extinct; as well as saber-toothed cats, giant beavers, large ground sloths, horses, camels, beavers, large ground sloths, horses, camels, giant bison, and some othersgiant bison, and some others

Some scientists believe that early humans Some scientists believe that early humans hurried the decline of these animals by hurried the decline of these animals by selectively hunting large formsselectively hunting large forms

Large MammalsLarge Mammals

AssignmentAssignment

Read Chapter 13, Section 4 (pg. 382-385)Read Chapter 13, Section 4 (pg. 382-385) Do Chapter 13 Assessment #1-26 (pg. 389-Do Chapter 13 Assessment #1-26 (pg. 389-

390)390) For Section 4: Do #’s 1, 8-10, 18, 26For Section 4: Do #’s 1, 8-10, 18, 26 Study for Chapter 13 Quiz!!!Study for Chapter 13 Quiz!!!