Chapter 24

Document Sample
Chapter 24 Powered By Docstoc
					                                      Mesozoic Paleogeography


Objectives
• Explain the breakup of Pangaea.
• Distinguish between the different tectonic characteristics
  of the Mesozoic Orogenies.

Vocabulary
  – Cordillera
                               Mesozoic Paleogeography


Mesozoic Paleogeography
• The Mesozoic Era
  consisted of the Triassic,
  Jurassic, and Cretaceous
  periods.
                                     Mesozoic Paleogeography


The Breakup of Pangaea
• The breakup of Pangaea was an important
  event that occurred during the Mesozoic Era.
  – Extreme heat from within Earth beneath Pangaea
    caused the continent to expand, cracking and breaking
    apart the lithosphere by the Late Triassic.
  – As the landmasses spread apart, the ocean flooded the
    rift valleys resulting in the formation of new oceans,
    including the Atlantic.
  – Some of the spreading areas joined together to form a
    continuous rift system called the Mid-Atlantic Ridge.
                                Mesozoic Paleogeography


Active Tectonism in Western North America
• Active subduction along the western coast
  of North America continued through the
  Middle Triassic.
  The Cordillera, which means ―mountain range‖
  in Spanish, refers to the mountain ranges that
  formed by subduction in western North America
  during the Mesozoic.
                                      Mesozoic Paleogeography


Active Tectonism in Western North America
• Three major episodes of orogenies—mountain-
  building—occurred along the western margin of
  North America during the Mesozoic.
  – The oldest orogeny was characterized by a large
    number of igneous intrusions and the resulting
    batholiths.
  – Beginning in the Late Jurassic and continuing through
    the Late Cretaceous, the next orogeny was
    characterized by low-angle thrust faulting and folding.
  – Beginning in the Late Cretaceous and continuing into
    the Cenozoic, the third Mesozoic orogenic event was
    characterized by vertical uplifts.
                                 Mesozoic Paleogeography


Seaways and Sand Dunes
• Throughout the Early and Middle Triassic, the
  supercontinent Pangaea and a single global
  ocean defined Earth’s paleogeography.
• The Triassic ended with a rapid drop in sea level
  that caused western North America to become
  much more arid and sandy.
• Strong winds shaped the sand into dunes that
  are preserved in large-scale, cross-bedded
  sandstone deposits.
                                       Mesozoic Paleogeography


Seaways and Sand Dunes
• Sea level rose again in the Jurassic, and a
  shallow sea covered central North America.
  – Deposits of the Late Jurassic river systems are
    preserved today as multicolored sandstones,
    siltstones, and mudstones.
  – The ocean continued to rise onto North America
    during the Cretaceous Period, flooding the entire
    southeastern margin of North America.
  – As a result, a sea covered the interior of North
    America from Texas to Alaska.
                                Mesozoic Paleogeography


Section Assessment
1. What caused rifts to form in Pangaea?
   Extreme heat from within Earth beneath
   Pangaea caused the continent to expand.
                                 Mesozoic Paleogeography


Section Assessment
2. What is the Cordillera?
   The cordillera refers to the mountain ranges that
   formed in western North America during the
   Middle Triassic.
                                      Mesozoic Paleogeography


Section Assessment
3. Identify whether the following statements are
   true or false.
   true
  ______ The Mid-Atlantic Ridge is still active today.
   false
  ______ The Cretaceous Period came before the
         Triassic Period.
   false
  ______ The Triassic ended with a dramatic rise in
         sea level.
   true
  ______ A sea covered the interior of North America
         during the Cretaceous Period.
                                                Mesozoic Life


Objectives
• Discuss why many paleontologists theorize that birds are
  descended from dinosaurs.
• Describe how paleontologists distinguish among reptile,
  dinosaur, and mammal fossils.
• Explain the evidence indicating that a meteorite impact
  caused the Cretaceous-Paleogene mass extinction event.
Vocabulary
  – modern fauna               – Saurischian
  – angiosperm                 – ectotherm
  – dinosaur                   – endotherm
  – Ornithischian              – iridium
                                          Mesozoic Life


Mesozoic Life
• The Mesozoic is commonly referred to as the
  Age of Reptiles.
• The first mammals, birds, and flowering plants
  appeared during the Mesozoic.
  Modern fauna refers collectively to the new
  marine organisms which arose during the
  Mesozoic.
                                           Mesozoic Life


Life in the Oceans
• The base of the food chain that supported all the
  large animals consisted of tiny, ocean-dwelling
  organisms called phytoplankton.
• Phytoplankton float near the surface of oceans
  and lakes and make their own food through the
  process of photosynthesis.
                                                Mesozoic Life


Life in the Oceans
Reef Builders Arise Again
  – Modern corals had evolved by the end of the Triassic.
  – A new group of clams called rudists developed the
    ability to build reefs during the Cretaceous.
  – Rudists built very porous reefs that today contain some
    of the largest Cretaceous oil deposits in areas such as
    west Texas.
                                               Mesozoic Life


Life in the Oceans
Important Index Fossils
  – Ammonites are related to modern nautiluses,
    octopuses, and squids.
  – Ammonites were abundant and diverse throughout the
    Late Paleozoic and Mesozoic, and their abundance
    indicates that they were very successful predators.
  – Swimming reptiles such as ichthyosaurs, plesiosaurs,
    and mosasaurs ruled the Mesozoic oceans during the
    Cretaceous.
                                            Mesozoic Life


Life on the Land
• During the Mesozoic the large, temperate coal
  swamps dried up, and the climate gradually
  warmed, dramatically changing life on land.
• Paleobotanists call the Mesozoic the Age
  of Cycads.
• Cycads are seed plants that do not have
  true flowers.
                                              Mesozoic Life


Life on the Land
Angiosperms Evolve
 – Angiosperms, which are seed-bearing plants that
   have flowers, evolved during the Cretaceous.
 – Before the Cretaceous, there were no flowers.
 – By the end of the Cretaceous, the land was covered
   with flowering trees, shrubs, and vines.
                                             Mesozoic Life


Life on the Land
Early Mammals
 – Small, primitive mammals evolved
   during the Late Triassic.
 – The structure of the lower jaw, middle
   ear, and teeth can be used to identify
   fossils of mammals.
 – A reptile has one ear bone and multiple
   lower jawbones, whereas a mammal
   has one lower jawbone and three
   ear bones.
 – Mammals have differentiated teeth
   while reptiles generally have only one
   kind of tooth.
                                                 Mesozoic Life


Life on the Land
Flying Reptiles
  – Pterosaurs were flying reptiles that dominated the air
    during the Mesozoic.
  – Pterosaurs had light, hollow bones, like modern birds.
  – The modification that allowed them to fly was the
    growth of a membrane from a greatly lengthened
    fourth finger.
  – Two groups of reptiles that arose during the Mesozoic
    and still exist are the crocodiles and turtles.
                                            Mesozoic Life


Dinosaurs Rule the Land
  Dinosaurs were a group of reptiles that
  developed an upright posture about 228 million
  years ago.
• Dinosaurs came in all sizes, from the very small to
  the extraordinarily large, and all were terrestrial.
• Although the largest dinosaurs were most likely
  slow and plodding animals, many of them were
  quick and agile.
                          Mesozoic Life


Dinosaurs Rule the Land
                                 Mesozoic Life


Dinosaurs Rule the Land
Dinosaur Hips
 – Two major groups of
   dinosaurs are recognized
   based on their hip
   structure: Ornithischia and
   Saurischia.
 – In ornithischian, or ―bird
   hipped‖ dinosaurs, the
   ischium and pubis were
   parallel to one another,
   similar to modern birds.
                                    Mesozoic Life


Dinosaurs Rule the Land
Dinosaur Hips
 – In Saurischian, or ―lizard
   hipped‖ dinosaurs, the ischium
   and pubis were at an angle to
   one another, similar to the
   orientation observed in
   modern lizards.
 – Scientists hypothesize that
   birds are actually descended
   from the Saurischia.
                                                Mesozoic Life


Dinosaurs Rule the Land
Dinosaur Hips
 – There were five different groups of ornithischian
   dinosaurs: stegosaurs, ankylosaurs, pachycephalosaurs,
   ceratopsians, and ornithopods.
   • All ornithischian dinosaurs were plant eaters, also
     called herbivores.
 – There were two different groups of saurischian
   dinosaurs: sauropods and theropods.
   • The sauropods were all quadrupedal, herbivores,
     and some grew to enormous sizes.
   • All theropods were bipedal and carnivores.
                                                 Mesozoic Life


Dinosaurs Rule the Land
Dinosaurs to Birds?
  – The idea that birds are related to dinosaurs stems from
    the amazing similarities between theropods and the
    oldest known bird, Archaeopteryx.
  – Fossils of feather impressions and a wishbone provide
    clear evidence that Archaeopteryx was definitely a bird,
    even though it did have teeth and a theropod-like
    skeleton.
                                                  Mesozoic Life


Dinosaurs Rule the Land
Ectotherm or Endotherm?
 – All living reptiles are ectotherms, meaning that their
   body temperatures vary in response to external
   temperatures.
 – All living mammals and birds are endotherms,
   meaning that they maintain relatively constant body
   temperatures, regardless of external temperatures.
 – At least some groups of dinosaurs may have been
   endotherms. but this hypothesis is still controversial.
                                           Mesozoic Life


Mass Extinctions
• A major mass extinction event ended
  the Mesozoic.
• Most major groups of organisms were
  devastated, and all known species of dinosaurs,
  pterosaurs, ammonites, mosasaurs, and
  plesiosaurs became extinct.
• Geologists theorize that a large meteorite
  slammed into the Yucatan Peninsula.
                        Mesozoic Life


Mass Extinctions
The circular shape
and underlying
layer of iridium-rich
rock provides
evidence of a
meteorite impact.
It was named the
Chicxulub crater
after a nearby
village.
                                                Mesozoic Life


Mass Extinctions
 Iridium is a metal that is rare in rocks at Earth’s
 surface but is relatively common in meteorites
 and asteroids.
 – Iridium is found in Cretaceous-Paleogene boundary
   sites worldwide, providing evidence of a major impact.
 – A buried crater in the Gulf of Mexico contains iridium,
   which has a radiometrically dated age of approximately
   65 million years.
 – Volcanism can also release high levels of iridium.
                                           Mesozoic Life


Mass Extinctions
• Most scientists agree that both a large meteorite
  impact and massive volcanism occurred at the
  end of the Cretaceous.
• The extraordinary stress that the impact added
  to an already stressed ecosystem likely caused
  the climax of the Cretaceous-Paleogene mass
  extinction.
                                                Mesozoic Life


Section Assessment
1. Match the following terms with their definitions.
   ___ angiosperm
    D                  A. a metal that is relatively common
                          in meteorites and asteroids
   ___ ectotherm
    C
                       B. animals that have relatively
   ___ endotherm
    B                     constant body temperatures,
   ___ iridium
    A                     regardless of outside
                          temperatures
                       C. animals that have body
                          temperatures that vary in
                          response to outside temperatures
                       D. seed-bearing plants that have
                          flowers
                                        Mesozoic Life


Section Assessment
2. What were the movement and diet characteristics
   of theropods?
  Theropods were bipedal carnivores.
                                               Mesozoic Life


Section Assessment
3. Identify whether the following statements are
   true or false.
   true
  ______ It is hypothesized that birds descended from
         the Saurischia.
   false
  ______ All living reptiles are endotherms.
   true
  ______ Dinosaurs are the only reptiles to have
         developed an upright posture.
   true
  ______ Crocodiles and turtles arose during the
         Mesozoic.
                                      Cenozoic Paleogeography


Objectives
• Describe the type of tectonism that characterized the
  Cenozoic orogeny.
• Understand the extent of glaciation that occurred in
  North America.

Vocabulary
  – Basin and Range Province
  – Tethys Sea
                          Cenozoic Paleogeography


Cenozoic Paleogeography
• The Cenozoic Era
  encompasses
  approximately the
  last 66 million years
  of Earth’s history to
  the present.
                                   Cenozoic Paleogeography


Cenozoic Paleogeography
The Ice Ages
 – The warm climate began to deteriorate during the
   Middle-to-Late Eocene, possibly due to a change in
   ocean circulation.
 – When Antarctica and
   Australia were
   connected, a current
   of warm water from
   the north moderated
   the temperature of
   Antarctica.
                                     Cenozoic Paleogeography


Cenozoic Paleogeography
The Ice Ages
 – When Antarctica was isolated over the south pole, a
   cold current began to flow around Antarctica, and
   glaciers began to form.
 – The climate began to warm again during the Early
   Miocene.
 – The glaciers on Antarctica began to melt, and the sea
   rose onto the margin of North America.
 – Glaciers returned to Antarctica during the Middle and
   Late Miocene, setting the stage for the ice ages of the
   Late Pliocene and the Pleistocene.
                                    Cenozoic Paleogeography


Cenozoic Paleogeography
The Ice Ages
 – During the Late Pliocene through the Pleistocene, the
   northern hemisphere experienced extensive glaciation,
   or an ice age.
   • Glaciers from the arctic advanced and retreated in
     at least four stages over North America.
   • The paths of the Ohio River and the Missouri River
     roughly mark the southernmost point to which
     glaciers advanced in North America.
                                      Cenozoic Paleogeography


Tectonic Events
• Western North America had been tectonically
  active throughout the Cenozoic.
  – The orogenic events that occurred at the end of the
    Mesozoic formed the Rocky Mountains.
  – The basins in Wyoming that filled with huge, swampy
    river deposits provided an ideal environment for the
    accumulation of vast amounts of coal.
  – The coal there is especially valuable because it has a
    very low sulfur content, and thus, it burns cleanly.
                                     Cenozoic Paleogeography


Tectonic Events
Subduction in the West
 – The Cascade Mountains are the result of the
   subduction of an oceanic plate beneath the western
   coast of North America at the end of the Eocene.
 – During the Miocene, the North American Plate was
   forced over the East Pacific Rise resulting in the
   creation of the San Andreas Fault.
 – The Basin and Range Province is a series of
   mountains that trend north-to-slightly-northeast, are
   separated by long, linear valleys, and extend from
   Nevada and western Utah to north-central Mexico.
                             Cenozoic Paleogeography


Tectonic Events
Subduction in the West
 – Extensional tectonism
   pulled the crust apart,
   causing large blocks of
   the crust to drop down
   along normal faults to
   form the basins,
   leaving other blocks at
   higher elevations to
   form the mountain
   ranges.
 – This extension is still
   occurring today.
                                      Cenozoic Paleogeography


Tectonic Events
Hot Spots in the West
  – Hot spots are mantle plumes that rise to Earth’s surface.
  – Some of the hot spots that occur in the western United
    States are related to the continuing subduction along
    the western coast of North America.
  – The land that makes up Yellowstone National Park is
    situated on a hot spot that has been active since the
    Early Cenozoic.
                                     Cenozoic Paleogeography


Tectonic Events
Continental Collisions
  – While the final breakup of Pangaea occurred during the
    Cenozoic, plate tectonics also brought continents
    together during this time.
    • The Himalayan Mountains formed when India
      traveled north and collided with the southern margin
      of Asia.
    • Africa collided with the connected landmass of
      Europe and Asia, or Eurasia, forming the Alps.
    • The Tethys Sea was a narrow sea that
      separated the two continents before Africa
      collided with Eurasia.
                               Cenozoic Paleogeography


Tectonic Events
The Tethys Sea had a
strong, westward-flowing
current that transported
organisms across long
distances. Cretaceous-aged
fossils from the Tethys Sea
are found as far west as the
Hawaiian Islands.
                               Cenozoic Paleogeography


Section Assessment
1. What was the extent of the North American
   glaciers of the Late Pliocene through the
   Pleistocene?
  The Ohio and Missouri Rivers roughly form the
  southern boundary of the glaciation.
                                Cenozoic Paleogeography


Section Assessment
2. Why is the coal found in Wyoming
   especially valuable?
  The coal in Wyoming is especially valuable
  because it has a very low sulfur content, and
  thus, it burns cleanly.
                                    Cenozoic Paleogeography


Section Assessment
3. Identify whether the following statements are
   true or false.
   true
  ______ Yellowstone National Park sits on top of a
         geologically active hot spot.
   false
  ______ The mountains in the Basin and Range
         Province were caused by uplift.
   false
  ______ The Himalayan Mountains were formed
         through a continental-oceanic collision.
   true
  ______ The Mediterranean Sea will likely become
         narrower over the next 50 million years.
                                                Cenozoic Life


Objectives
• Describe the landscape of the Oligocene in Central
  North America.
• Discuss the changes in animals in North America during
  the Cenozoic.
• Identify the characteristics of primates.
• Explain what separates hominids from the other
  hominoids.

Vocabulary
  – primate                        – hominid
  – hominoid                       – Homo sapiens
                                           Cenozoic Life


Cenozoic Life
• The modern marine fauna, including clams,
  snails, sea urchins, crustaceans, bony fishes,
  and sharks, survived the Cretaceous mass
  extinction to populate the modern oceans.
• Whales and dolphins evolved during the
  Cenozoic as completely aquatic mammals.
• Walruses and sea lions returned to the oceans
  but remain partly terrestrial today.
                                          Cenozoic Life


Life on Land
• Most of the currently living groups of mammals
  had evolved by the Eocene.
• Forests dominated North America during the
  Paleocene and Eocene, giving way to open land
  as the climate cooled during the Late Eocene.
• Grasses, which were important to many large
  mammals, appeared during the Eocene.
• The resulting savannas supported a large
  diversity of mammals, most of which are
  members of groups living today.
                                              Cenozoic Life


Life on Land
Pleistocene Mammals
 – As the Pliocene ice age began, the great savannas
   were replaced by more arid land.
 – The change in climate
   caused many of the
   savanna mammals to
   become extinct.
 – A new group of animals,
   such as the woolly
   mammoth, dire wolf,
   and sabre-toothed cat,
   evolved and populated
   the land.
                                             Cenozoic Life


Primates and Humans
• The scarcity of fossils is a difficult problem to
  overcome in studies of the origin of humans and
  our relationship to other primates.
• The discovery of a single new fossil can
  dramatically change our understanding.
                                               Cenozoic Life


Primates and Humans
Primates
 – Primates are distinguished from other mammals by a
   grasping hand with an opposable thumb and two eyes
   directed forward that result in stereoscopic vision.
 – Other primate characteristics include smaller, fewer,
   and less-specialized teeth than other mammals and a
   relatively large brain.
                                              Cenozoic Life


Primates and Humans
Primates
 – Hominoids are a primate group that includes hominids
   and the great apes.
 – Hominids, the group of hominoids that includes Homo
   sapiens, are differentiated from other hominoids by
   being bipedal with an upright posture, having larger
   brains, smaller canine teeth, and smaller faces than
   other hominoids, and through the use of sophisticated
   tools due to greater manual dexterity.
                                                Cenozoic Life


Primates and Humans
The Rise of Homo Sapiens
 – Homo sapiens is the species to which humans belong.
 – In the 1850s, a fossilized Neanderthal skull was
   discovered in Neander Tal near Dusseldorf, Germany.
 – Most fossil evidence indicates that Neanderthals were
   most likely a side branch of H. sapiens and not direct
   ancestors of modern humans.
 – The Neanderthals were hunters that inhabited Europe
   and the Near East approximately 200 000 to 30 000
   years ago.
                                       Cenozoic Life


Primates and Humans
The Rise of Homo Sapiens
 – Neanderthals had heavier
   brows, mouths that projected
   forward, receding chins, more
   massive, muscular bodies, and
   slightly larger brains than
   modern humans do.
  – A characteristic of Neanderthals
    (top) is a gap that occurs
    between the rear teeth and the
    jaw bone. Modern humans
    (bottom) do not possess this
    gap.
                                                 Cenozoic Life


Primates and Humans
The Rise of Homo Sapiens
 – There is evidence that Neanderthals buried their dead
   and placed items such as tools in their graves.
 – The fossil skeleton of Australopithecus afarensis
   provides evidence that bipedal, upright-walking
   hominids existed at least 3.5 million years ago.
 – Compared to the rest of the fossil record, there are
   relatively few hominid fossils.
                                               Cenozoic Life


Section Assessment
1. Match the following terms with their definitions.
   ___ primate
    C                     A. a group of bipedal primates
   ___ hominoids
    D                        with upright posture that use
                             sophisticated tools
   ___ hominids
    A
                          B. the process of collecting
   ___ Homo sapiens
    B                        data about Earth from far
                             above Earth’s surface
                          C. the species to which
                             humans belong
                          D. a primate group that
                             includes the great apes
                                         Cenozoic Life


Section Assessment
2. What type of land animals dominated the
   Eocene? What allowed them to evolve?
  Large mammals evolved and dominated the
  Eocene as grasslands, or savannas, became
  common.
                                               Cenozoic Life


Section Assessment
3. Identify whether the following statements are
   true or false.
   false
  ______ Modern humans descended from
         Neanderthals.
   false
  ______ Bipedal, upright-walking hominids existed at
         least 8.5 million years ago.
   true
  ______ Neanderthals had slightly larger brains than
         modern humans.
   true
  ______ Most of the modern marine fauna survived the
         Cretaceous mass extinction.
                     Chapter Resources Menu


Study Guide
 Section 24.1
 Section 24.2
 Section 24.3
 Section 24.4


Chapter Assessment
Image Bank
                                   Section 24.1 Study Guide


Section 24.1 Main Ideas
• Geologists hypothesize that Pangaea broke
  apart as heat built up beneath it. Expansion
  occurred and ultimately resulted in the rifting
  apart of Pangaea.
• The first orogeny is characterized by igneous
  intrusions, whereas the second orogeny is
  characterized by thrust faulting and folding.
                                 Section 24.2 Study Guide


Section 24.2 Main Ideas
• The modern marine fauna include crabs, lobsters,
  shrimps, sponges, sea urchins, modern corals,
  snails, and clams. The major vertebrate groups of
  the modern fauna include bony fishes, sharks,
  aquatic reptiles, and aquatic mammals.
• The oceans contained vast numbers of
  ammonites that are now index fossils. The most
  common land plants were cycads, and the
  dominant land animals were dinosaurs.
• An upright posture distinguishes dinosaurs from
  other reptiles.
                                 Section 24.3 Study Guide


Section 24.3 Main Ideas
• The Cenozoic tectonism is characterized by
  vertical normal faulting.
• During the Pleistocene, glaciers extended as
  far south as the courses of the Ohio and
  Missouri Rivers.
                                  Section 24.4 Study Guide


Section 24.4 Main Ideas
• Large mammals evolved to feed on the
  abundant grasslands that developed during the
  Cenozoic. As the ice ages approached, many of
  the mammals that lived on these grasslands
  became extinct and were replaced by large
  mammals that were adapted to the cold and arid
  land south of the glaciers.
• Primates are mammals that developed
  specialized traits, including a grasping hand
  with an opposable thumb, stereoscopic vision,
  smaller, fewer, and less-specialized teeth, and a
  relatively large brain.
                                          Chapter Assessment


Multiple Choice
1. How many episodes of orogenies did the
   western margin of North America experience
   during the Mesozoic?
  a. one                       c. three
  b. two                       d. four

  The three episodes of orogenies along the western
  margin of North America during the Mesozoic resulted in
  a tremendous number of igneous intrusions, low-angle
  thrust faulting, and vertical uplifts.
                                           Chapter Assessment


Multiple Choice
2. What organism was the base of the marine food
   chain during the Mesozoic?
  a. phytoplankton              c. coral
  b. trilobites                 d. sponges


  Phytoplankton are tiny, ocean-dwelling organisms that
  float near the surface of the oceans and make their own
  food through photosynthesis. They are still the base of
  the marine food chain today.
                                             Chapter Assessment


Multiple Choice
3. All ornithischian dinosaurs were ____.
  a. carnivores                   c. endotherms
  b. herbivores                   d. ―lizard hipped‖


  There were five different groups of ornithischian
  dinosaurs: stegosaurs, ankylosaurs, pachycephalosaurs,
  ceratopsians, and ornithopods. They were ―bird-hipped‖
  even though modern birds probably descended from
  saurischian, or ―lizard hipped‖ dinosaurs. It is possible that
  some were endotherms, but it is not widely accepted that
  all were.
                                         Chapter Assessment


Multiple Choice
4. Which of the following is a modern remnant of
   the Tethyan Sea?
  a. Arctic Ocean              c. North Sea
  b. Baltic Sea                d. Mediterranean Sea


  The Tethyan Sea separated Eurasia from Africa. As
  Europe and Africa continue to collide, the Mediterranean
  Sea will become narrower over time as the two continents
  move toward each other.
                                          Chapter Assessment


Multiple Choice
5. All hominids are ____.
  a. bipedal                    c. herbivores
  b. carnivores                 d. Neanderthals



  The most recognizable feature that differentiates
  hominids from other hominoids is that they are bipedal.
  They have an upright posture resulting from the
  modification of the hipbone and they walk on two legs.
  Homo sapiens are hominids.
                                      Chapter Assessment


Short Answer
6. What event led to the mass extinction that
   ended the Mesozoic?
  It is generally accepted that a large meteorite
  impact and massive volcanism occurred at the
  end of the Cretaceous. In the midst of a
  stressful time of climatic cooling, changing plant
  populations and a gradual decline in dinosaur
  diversity and abundance, the impact of a large
  meteorite likely caused the climax of the
  Cretaceous-Paleogene mass extinction.
                                   Chapter Assessment


Short Answer
7. How were Neanderthals different from
   modern humans?
  Neanderthals had heavier brows, mouths that
  projected forward, receding chins, more massive,
  muscular bodies, and slightly larger brains than
  modern humans do. They also had a gap
  between their rear teeth and their jaw bone.
                                         Chapter Assessment


True or False
8. Identify whether the following statements are true
   or false.
  ______ The Basin and Range Province formed through
   false
         compressional tectonism.
  ______ Mammals have two sets of teeth whereas
   true
         reptiles continuously replace older teeth.
  ______ Ginkgoes are an example of an angiosperm.
   false
  ______ Ammonites are important Mesozoic index fossils.
   true
  ______ Iridium is not common in rocks at Earth’s surface.
   true
  ______ All hominoids are bipedal with an
   false
         upright posture.
                    Image Bank


Chapter 24 Images
                    Image Bank


Chapter 24 Images
                    Image Bank


Chapter 24 Images
To navigate within this Interactive Chalkboard product:
           Click the Forward button to go to the next slide.

           Click the Previous button to return to the previous slide.

           Click the Chapter Resources button to go to the Chapter Resources
           slide where you can access resources such as assessment questions
           that are available for the chapter.

           Click the Menu button to close the chapter presentation and return to
           the Main Menu. If you opened the chapter presentation directly without
           using the Main Menu this will exit the presentation. You also may press
           the Escape key [Esc] to exit and return to the Main Menu.

           Click the Help button to access this screen.

           Click the Earth Science Online button to access the Web page
           associated with the particular chapter with which you are working.

           Click the Speaker button to hear the vocabulary term and definition
           when available.
     End of Custom Shows
This slide is intentionally blank.

				
DOCUMENT INFO
Shared By:
Categories:
Stats:
views:32
posted:4/28/2011
language:English
pages:82