Chapter 26 Cenozoic Life

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Chapter 26

Cenozoic Life

GUIDED STUDY

The text chapter should be studied one section at a time. Life on Land (pp. 552-560) Before you read, preview each section by skimming it, noting headings and boldface items. Then read the 5. Describe the adaptations of grasses and herbaceous appropriate section objectives from the following plants that caused their spectacular radiation in the outline. Keep these objectives in mind and, as you read Cenozoic. the chapter section, search for the information that will enable you to meet each objective. Once you have finished a section, write out answers for its objectives.

Cenozoic Marine Life (pp. 550-552)

1. List examples of major invertebrate groups that were missing from Cenozoic seas. 6. Discuss the diversification of birds in the Cenozoic, and the dominant roles they played.

2. Describe the diversification of foraminifera during the early Cenozoic. 7. Marsupial mammals developed in both South America and Australia. Why did those in South America suffer greatly from extinction in the Pliocene Epoch, but those in Australia have survived untouched until modern times?

3. Which marine invertebrates seemed little affected by the Cretaceous-Tertiary extinction event?

8. Describe the different stages in the development of the modern horse. What features underwent the most change, and why? 4. Describe the various forms that led to the evolution of whales from original land-based predators.

Quaternary Extinctions (pp. 560-562) CHAPTER REVIEW

9. Describe the kinds of animals, both mammal and When you have finished reading the chapter, work bird, that were lost in the late Quaternary extinction through the material that follows to review it. Complete event. the sentences. As you proceed, evaluate your performance for each section by consulting the answers on page 245. Do not continue with the next section until you understand each answer. If you need to, review or reread the appropriate section in the textbook before continuing.

10. Describe how an abrupt climate change at the end of the Pleistocene could have been fatal to the large Introduction (p. 549) animal population at that time.

1. Fossils of creatures that lived in and around large lakes in what is now Utah, Wyoming, and Colorado during the Eocene Epoch are preserved in rocks of the ______. Human Origins (pp. 562-569) 2. The warm, tropical climate of the region was 11. Describe the features that characterize primates. indicated by the presence of fossilized ______trees What advantages do these features offer? and ferns. 3. The abundance of fossil ______skeletons in these layers indicate a poisonous overturning of oxygen- rich surface waters with oxygen-poor bottom waters, causing massive kills. Cenozoic Marine Life (pp. 550-552) 12. List several differences between the two major groups of primates. 4. The mass extinctions at the end of the ______Era included all of the large marine ______, and the ammonoid cephalopods and rudistid bivalves. 5. ______diversified quite rapidly in the early 13. Describe the fundamental structural differences between modern humans and apes. Cenozoic, with ______forms reaching the size of a five-cent piece. 6. ______seemed to have flourished with the increase of volcanism during the Miocene Epoch, when increased volcanism loaded the waters with 14. What are the most significant features of the silica from which their tests were built. recently discovered Australopithecus garhi? 7. With the extinction of the reef-building rudistid bivalves, the ______reclaimed their role by the Oligocene Epoch.

8. ______were little affected by the 19. The demise of the ______opened the way for Cretaceous-Tertiary event, and are a main rapid diversification of both mammals and ______component of temperate-water reefs today. in the Cenozoic. 9. ______and ______quickly reestablished 20. Despite the prominence of gymnosperms and many their dominance in the shallow marine environment, seedless vascular plants in some environments with the rapid appearance of many modern forms. today, it is the continued expansion of the 10. Their chief new adaptation was to inhabit the ______that highlights Cenozoic plant ______shallow marine environments. evolution. 11. The cephalopods were severely impacted by 21. The cooler and drier climate of the Miocene Epoch extinctions, with only a single genus of favored the expansion of ______, which had ______surviving. adapted to the grazing habits of mammals. The 12. Echinoids such as the familiar______, physical toughness of these plants comes from their evolved to take advantage of the sandy, shallow incorporation of ______into the cell structure. marine environment. 22. Colonization of spaces made vacant by flood or fire 13. The ammonoid predators of the Mesozoic were was a special adaptation of the ______plants, replaced in the Cenozoic by modern fish called which also underwent a spectacular radiation in the ______, which have symmetrical fins, round later Cenozoic. scales, and short jaws. 23. Today, the surviving reptiles are mostly ______, 14. Larger marine predators such as ______which include crocodiles, lizards, and snakes. The evolved during the Tertiary Period, with one form only other surviving reptile group was the reaching nearly 40 feet in length. ______. 15. The largest marine predators of the Cenozoic were 24. By the end of the Mesozoic, the modern design of the ______, as they are today. They seem to birds with a ______beak, hollow ______, have evolved from wolf-sized, hoofed ancestors and the absence of a reptilian tail was established. that were adapted to an aquatic environment. 25. In the Early Tertiary Period, scavenging birds such 16. The earliest whale ancestors had functional hind as vultures and large______forms appeared. limbs and have been found in ______, Some of the later carnivorous forms stood 2 meters but later forms retain only ______of these limbs, tall and were probably the dominant ______of and appear to be adapted to a fully aquatic the time. existence. 26. In isolated locations such as Madagascar and New 17. Most whales today are______forms, but by the Zealand, giant flightless birds survived until the Miocene, the larger ______whales appeared, Pleistocene, when ______with mammals and which include today the largest animals that have hunting by humans ______them to extinction. ever lived on Earth. 27. Because of the long presence of the dinosaurs, ______of mammals was relatively slow Life on Land (pp. 552-560) before the start of the Cenozoic Era. 18. The evolution of ______on land far 28. In the early Paleocene Epoch, only about a ______outdistanced diversification in the oceans. families of mammals existed. By the early Eocene epoch, there were already ______families present.

29. The early mammals were very small and their 38. Flesh-eating placental mammals are called fossils are quite scarce. Fortunately, their ______. They form the most diverse and ______and _____ structures are very complex of all mammalian orders, and are distinctive, and can be used for identification. characterized by specialized teeth, and keen senses 30. There are five subclasses of mammals. One of the of sight and ______. These mammals can be two subclasses that arose in the Mesozoic and divided into three groups or superfamilies became extinct in the early Cenozoic was the 39. The group containing cats, civets, and hyenas is ______. called the ______. Dogs, bears, racoons, and 31. The most primitive of the three mammal subclasses weasels belong to the ______group. The marine present today are the ______, which lay group is called the ______, and includes eggs and nurse their young. They can be traced seals, sea lions, and walruses. back to Cretaceous fossils. 40. Mammals having hoofed feet are called 32. The group of mammals in which the embryo ______. Horses, rhinoceroses, and tapirs are hatches in the uterus and continues its development classified as being ______, or perissodactyls. there are called ______. Deer, giraffes, bison, pigs, and hippopotamuses as 33. ______has been a factor in the evolution of are classified as being ______, or artiodactyls. this mammalian group, for in areas such as South 41. The competitive success of the artiodactyls against America, where landbridges suddenly forced these their perissodactyl neighbors may have come by animals into direct competition with more advanced their development of a multi-chambered stomach, mammal groups, they eventually became which gave these ______an advantage in ______. In areas such as Australia, they have more efficient digestion. flourished in the absence of outside competition, 42. The largest land animals alive today evolved from until only recently. hoofed ancestors, and are recognized by their long 34. ______mammals have the most advanced trunks or modified noses. These ______system of reproduction. They evolved from gave rise to the mammoths, mastodons, and modern marsupial ancestors during the Cretaceous Period elephants. and quickly became widespread. Quaternary Extinctions (pp. 560-562) 35. The first mammals of this most advanced group were the ______, and all other groups 43. Only 12,000 years ago, an astoundingly diverse probably evolved from them. Diversification of large mammal fauna inhabited the northern placental mammal orders occurred in the hemisphere, including both grazing and carnivorous Paleocene, Eocene, and later Miocene or Pliocene mammals. Between ______and ______years epochs. ago, nearly all of these large animals disappeared.. 36. Placental mammals with few or no teeth are the 44. Extinction rates of large mammals were greatest in ______, and are represented today by tree North and South America, where _____ and _____ sloths, anteaters and ______. of the genera were lost. In Europe and Asia, 37. The ______are the most successful of all extinction rates were much less at this time, at about mammal orders, and account for 40% of all living 30% and 5%. mammal species.

45. One hypothesis for the large mammal extinctions ______. Their descendants at some time migrated to South America and radiated suggests that a sudden ______change was independently to give rise to the ______responsible. ______. 55. The ______that lived in the cooler, drier 46. The ______blames hunting by Miocene climates of Africa had a long torso and humans for the loss of species. Spear points found limbs that were ______, but a skull, jaws, with the bones of these giant mammals have been and teeth that were ______. These features dated at about the same age as their extinctions, and suggest that these forms were ancestral to both the at about the same time as the widespread great apes and the hominids appearance of people in this region. A ______56. The skeletal differences between apes and humans of both hypotheses may have ultimately caused the include a shorter ______, shorter limbs, and a large mammal extinctions. skull that houses a ______. 57. The human skull differs from that of the ape in its Human Origins (pp. 562-569) flattened ______, smaller ______, and reduced canine teeth. 47. Humans belong to the mammal order called 58. The pathway leading from the ape-like Miocene ______. These history of these mammals is families to the hominids disappears for lack of difficult to study, because their remains were never ______remains. 59. Discoveries of early hominid fossils as old as 4.4 large or abundant. million years have come from sediments of the 48. Important characteristics of members of this order ______. include ______fingers and toes, opposable digits 60. Ardipithecus ramidus fossil remains show a that are adapted to ______, and front-set eyes ______of human and apelike features. that create overlapping fields of ______. 49. This order can be divided into two main groups. 61. Slightly younger hominid fossil remains have been collectively termed ______. Although The tree shrews, lemurs, tarsiers, and lorises are their faces were apelike, their pelvis indicates that ______. They have ______toes and they clearly walked ______. 62. Up to seven species of Australopithecus have been ______snouts that represent a lack of assigned, including both ______and ______evolutionary advancement. forms. A. garhi is the most exciting find of al, for with its bones were found ______and 50. The more advanced forms such as the Old World animal bones with cut marks on them. monkeys, New World monkeys, and hominoids are 63. A recent Kenyan find, Kenyanthropus platyops, is ______. They have a more upright dated at 3.5 million years ago. Its strong ______, and flatter ______. resemblance to members of the much younger 51. Hominoids can be divided into the lesser apes, the genus Homo may remove the australopithecines as great apes, and the ______. the ______of modern humans. 64. The disappearance of forests in East Africa caused 52. Purgatorius may have been the earliest primate, by the onset of glaciation in the Late Pliocene may having lived during the Late ______Age. have caused early humans to travel greater distances 53. Early prosimian remains have been found in the in search of food. Evidence of this can be seen in Paleocene and Eocene of North America and Asia, the ______leg bones and changes in the ______. but the North American stock was ______by 65. The first species of the genus Homo was named Oligocene climate change. The Middle Eocene habilis because of its ability to use ______. It was no larger than its contemporary australopithecines, fossil ______had both prosimian and but it had a bigger ______. anthropoid characteristics, putting it at the base of 66. ______was the first hominid to appear on the anthropoid family tree. other continents. This form had better developed 54. Aegyptopithecus was an anthropoid primate that stone tools, and may have used fire. may have been an ancestor to the ______

67. Between 200,000 and 30, 000 years ago, larger, c. parallel evolution. more muscular forms occurred in Europe and the d. the adaptive radiation of the surviving plants and Near East called ______. DNA studies of animals. their remains suggest they are a separate species of humans from modern peoples. 3. Marine life at the beginning of the Tertiary Period 68. The origin of our own species, ______, was completely devoid of: has been explained by two different theories. The a. brachiopods. ______theory suggests that modern b. cephalopods. humans arose from ancestral stocks present in c. large marine reptiles. several regions simultaneously, such as from the d. teleost fishes. widespread species Homo erectus. 69. The ______hypothesis proposes that 4. Tertiary bivalves occupied additional niches, such migrations of modern people from Africa populated as the: the entire world. This idea is supported by studies a. shifting shoreline sands. of ______DNA. b. waters of salt lakes. 70. The European newcomers were a nomadic people c. land surface. with a distinctive culture, termed ______, d. seasonal mud flats. which was characterized by the manufacture of elaborate tools, decorative arts, musical 5. Most modern fishes are: instruments, and even elegant paintings of large a. sharks. mammals now ______. b. teleosts. 71. The presence of humans in southeast Asia and c. placoderms. Australia 35,000 to 40,000 years ago suggests that d. lobe-fins. the development of ______technology had already occurred. As a result, settlement of the 6. The largest marine predators of the Cenozoic were: Americas by humans could have occurred long a. mosasaurs. before the opening of the ______b. giant sharks. ______near the end of the Pleistocene c. baleen whales. allowed land passage between Asia and North d. toothed whales. America. 72. The greatest threats to modern humans come today 7. The herbaceous plants flourished in: from ______, exhaustion of natural resources, a. jungles. and human-induced ______. b. grasslands. c. spaces opened by fire or flood. d. deep forests. PRACTICE TESTS 8. Modern birds are characterized by: After you thoroughly understand the correct answers of a. a toothless beak. the Chapter Review, answer the following questions and b. hollow bones. check them with the answers on page 245-246. If your c. a short, non-reptilian tail. answer is incorrect, consult the appropriate pages of the d. all of the above. text. 9. Giant flightless birds survived until the Pleistocene Multiple Choice Questions in: a. South America. Circle your answers to the following questions. b. Australia. c. North America. 1. The numerous fish fossils found in the Early d. Africa. Tertiary Green River Formation were killed by: a. overturn of lake waters. c. submarine landslide. 10. Mesozoic mammals that became extinct in the Early b. volcanic eruptions. d. None of the above. Tertiary Period were called: a. multituberculates. 2. The Earth today is populated by the descendants of b. monotremes. animals that restocked the land after the mass c. marsupials. extinction at the Mesozoic-Cenozoic boundary by: d. placentals. a. the evolution of many new, bizarre animals and plants. 11. The first placental mammals to appear were b. convergent evolution. Cretaceous:

a. edentates. b. overhunting by humans. b. carnivores. c. a combination of a. and b.. c. primates. d. None of the above. d. insectivores. 21. Primate hands are adapted for: 12. Armadillos are: a. grasping. a. marsupials that migrated north from South b. tearing. America. c. digging. b. placentals that migrated South from North d. running. America. c. placentals that migrated north from South 22. The early Tertiary primates, which had long snouts America. and clawed fingers were: d. marsupials that migrated south from North a. anthropoids. America. b. prosimians. c. hominids. 13. The most successful of mammals are the: d. hominoids. a. edentates. b. rodents. 23. The lesser apes, great apes, and humans are: c. carnivores. a. anthropoids. d. ungulates. b. prosimians. c. hominids. 14. The largest odd-toed ungulates were : d. hominoids. a. horses. b. chalicotheres. 24. Australopithecus and Homo are: c. rhinoceroses. a. anthropoids. d. brontotheres. b. prosimians. c. hominids. 15. The origin of camels occurred in: d. hominoids. a. Africa. b. Asia. 25. The australopithecine species found with stone tools c. Australia. and scraped animal bone was: d. North America. a. A. afarensis. b. A. garhi. 16. Elephants obtain food with their: c. A. robustus. a. trunk. d. A. africanus. b. teeth. c. tusks. 26. Australopithecines coexisted with: d. front legs. a. Homo habilis. b. Homo sapiens. 17. The Paleocene origin of horses occurred in: c. Homo erectus. a. North America. c. Africa. d.. Kenyanthropus platyops. b. Asia. d. Europe. 27. Modern humans are assigned to: 18. Until 12,000 years ago, large mammals roamed: a. Homo habilis. a. Asia. b. Homo sapiens. b. Europe. c. Homo erectus. c. North America. d.. Kenyanthropus platyops. d. South America. True or False Items 19. Mammoths on Wrangel Island were small because of: Write true or false on the line in front of each statement. a. the extreme cold. b. a limited food supply. _____ 1. The Green River Formation represents an c. the thin ice surrounding the island. Eocene lake deposit. d. the large forests on the island. _____ 2. Sharks were the most common marine predators of the Early Cenozoic Era. 20. The large mammal extinctions at the end of the _____ 3. Planktonic foraminifera evolved rapidly, and Pleistocene were probably caused by: are excellent index fossils for much of the a. climate change. Cenozoic Era.

_____ 4. Bivalves and gastropods were devastated by 2. The limestone blocks comprising the pyramids of the Cretaceous-Tertiary mass extinctions. Egypt contains fossils of the large benthic _____ 5. Toothed whales are the largest animals that ever lived. foaraminifers called ______. _____ 6. Grasses and herbaceous plants were 3. With the extinction of the ______, angiosperms that expanded their range in the Cenozoic. the scleractinian corals returned as the prominent _____ 7. The remaining Cenozoic reptiles were marine reef-builders. primarily synapsids. _____ 8. Marsupial mammals rear their young in an 4. The teleost fishes took over the marine predatory external pouch. role previously occupied by the ______. _____ 9. Armadillo fossil remains can be found as far back as the Cretaceous. 5. The largest Cenozoic marine predators were _____ 10. The carnivores are the most successful of all ______. the mammal orders. _____ 11. Dogs, bears, and racoons are canids. 6. The Cenozoic Era could be described as the “Age of _____ 12. Brontotheres and chalicotheres are extinct Mammals” or the “Age of ______“. odd-toed ungulates. _____ 13. Camels originated in Asia. 7. Grasses were favored by the cooler, drier climates _____ 14. Mammoths and Mastodons are extinct of the ______. proboscideans. _____ 15. The large mammal fauna became extinct last 8. The large, flightless birds of the early Tertiary in Asia. Period have been interpreted as both carnivores and _____ 16. Primates have five fingers with opposable digits. ______. _____ 17. Kenyanthropus may actually be the direct 9. The most primitive living group of mammals are the ancestor of humans. _____ 18. Different species of humans have not monotremes, which lay ______, but nurse their coexisted in time. young. Essay Questions 10. In marsupials, the egg hatches in the uterus, and the embryo continues development in a modified, Write a brief essay on a separate sheet of paper answering each of the following questions. external ______. 11. Placental mammals have the most advanced system 1. Discuss the evolutionary record of the whales. 2. Explain the adaptations of grasses that made them of ______. so successful. 12. The oldest mammal order is the insectivores, which 3. What two hypotheses seek to explain the extinction of the Late Pleistocene large mammal fauna? is represented by shrews, ______, and 4. Why is the search for human ancestry so full of hedgehogs. complications and controversy? 13. Rodents number over ______of all living mammal CHALLENGE TEST species.

Answer these questions the day before an exam as a 14. Flesh-eating placental mammals include cats, dogs, final check on your understanding of the chapter’s terms and ______. and concepts. Check your responses with the answers on pages 247. If your answer is incorrect, consult the 15. Ungulate mammals are divided on the basis of the appropriate pages of the text. number of their _____.

Completion 16. Quaternary large-mammal extinctions are commonly attributed to the ______activities of humans. Fill in the correct answers. 17. Humans belong to the ______division of anthropoids. 1. The sediments of the Green River Formation were 18. Humans belong to the ______family of deposited in exceptionally ______. hominoids.

19. Humans belong to the ______genus of hominids. 11. Seals, sea lions, and walruses are: 20. The use of tools was once thought to distinguish a. felids. early humans from their ______b. canids. neighbors. c. pinnipeds. d. toothed whales. Multiple-Choice Questions 12. Horses are: Circle the correct answer. a. odd-toed ungulates. b. even-toed ungulates. 1. The largest Cenozoic protozoans were: c. odd-toed ruminants. a. planktonic foraminifers. d. even-toed ruminants. b. benthic foraminifers. c. planktonic fusulinids. 13. Even-toed ungulates were successful because of: d. benthic fusulinids. a. fast hooves. b. better eyesight. 2. Later Cenozoic corals were important reef-builders, c. lightweight design. supplemented in temperate waters by colonies of: d. a multichambered stomach. a. belemnites. c. rudists. b. brachiopods. d. bryozoans. 14. Large mammal extinctions in North America followed the arrival of: 3. Whales evolved from: a. mammoths c. humans. a. fishes c. sharks. b. mastodons. d. horses. b. marine reptiles. d. land mammals. 15. Humans belong to the: 4. The largest animals that ever lived were: a. rodents. a. dinosaurs c. baleen whales. b. primates. b. giant sharks . d. pliosaurs. c. insectivores. d. edentates. 5. The grasses were most successful in which climate? a. warm, dry. c. cool, dry. 16. Old world monkeys, New world monkeys, and apes b. warm, wet. d. cool, wet. are: a. anthropoids. 6. The early Tertiary multituberculate mammals were b. prosimians. eventually outcompeted by: c. hominids. a. placental rodents. c. marsupials. d. hominoids. b. placental primates. d. monotremes. 17. The actual ancestor of humans may be: 7. The monotremes are characterized by: a. Australopithecus afaresis. a. pouches. c. a placenta. b. Australopithecus robustus. b. egg-laying ability. d. multi-cusped teeth. c. Australopithecus africanus. 8. The only marsupial native to North America is the: d. Kenyanthropus platyops. a. opossum. b. kangaroo. 18. The earliest hominid to be found outside of Africa c. koala. was : d. wombat. a. Homo habilis. b. Homo sapiens. 9. Carnivores are flesh-eating: c. Homo erectus. a. therapsids d.. Kenyanthropus platyops. b. momotremes c. placentals True or False Items d. marsupials Write true or false on the line in front of each statement. 10. Felid carnivores include the famous a. cave bear. _____ 1. The fossilized fish skeletons in the Green b. saber-tooth cat. River Formation were killed by a nearby c. dire wolf. volcanic eruption. d. chalicothere.

_____ 2. Early Tertiary planktonic foraminifers reached 24. toothless; bones the size of a five-cent piece. 25. flightless; predators _____ 3. Bivalves became established in the 26. competition; drove environment of shifting shoreline sands. 27. diversification _____ 4. Toothed whales were the largest marine 28. dozen; 100 predators of the Tertiary Period. 29. tooth; jaw _____ 5. Large flightless birds such as Diatryma were 30. multituberculates herbivorous. 31. monotremes _____ 6. Multituberculate mammals survived into the 32. marsupials Eocene Epoch. 33. Tectonics; extinct _____ 7. Monotremes are the most advanced of 34. Placental today’s remaining mammal groups. 35. insectivores _____ 8. Insectivores are the earliest of the placental 36. edentates; armadillos mammals. 37. rodents _____ 9. Cats, civets and hyenas are pinniped 38. carnivores; smell mammals. 39. felids; canids; pinnipeds _____ 10. Odd-toed ungulates were once called 40. ungulates; odd-toed; even-toed perissodactyls. 41. ruminants _____ 11. Horses are even-toed ungulates. 42. proboscideans _____ 12. The multichambered stomach gave 43. 12,000; 8,000 ruminants a selective advantage in the 44. 75%; 80% digestion of coarse plant material. 45. climate _____ 13. The Overkill hypothesis suggests that 46. Overkill hypothesis; combination overhunting by humans brought the large 47. primates Pleistocene mammals to extinction. 48. five; grasping; vision _____ 14. Anthropoids have primitive features such as 49. prosimians; clawed; elongated clawed fingers and elongate snouts. 50. anthropoids; posture; face _____ 15. Hominoids include monkeys and apes. 51. hominids _____ 16. Ardipithecus ramidis is the oldest hominid. 52. Cretaceous _____ 17. Humans of today continue to evolve rapidly. 53. eliminated; Eosimias 54. Old World monkeys; New World monkeys ANSWERS 55. dryomorphs; monkey-like; ape-like 56. pelvis; large brain CHAPTER REVIEW 57. face; jaw 58. fossil 1. Green River Formation 59. East African Rift 2. palm 60. mix 3. fish 61. australopithecines; upright 4. Mesozoic; reptiles 62. robust; gracile; stone tools 5. Foraminifera; benthic 63. true ancestors 6. Diatoms 64. longer; pelvic 7. scleractinian corals 65. tools; brain 8. Bryozoans 66. Homo erectus 9. Bivalves; gastropods 67. Neanderthals 10. high-energy 68. Homo sapiens; multiregional origin 11. nautiloid 69. out of Africa; mitochondrial 12. sand dollar 70. Cro-magnon 13. teleosts 71. sea-faring; Bering landbridge 14. sharks 72. pollution; climate change 15. whales 16. river sediments; vestiges PRACTICE TESTS 17. toothed; baleen 18. mammals Multiple-Choice Questions 19. dinosaurs; birds 20. angiosperms 1. a 21. grasses; silica 2. d 22. herbaceous 3. c 23. diapsids; turtles 4. a

5. b Essay Questions 6. d 7. c 1. The origin of whales can be traced through several 8. d intermediate forms which show similar but 9. b modified features relating to the limbs of the 10. a animals: 11. d a. The earliest whales from the early Eocene Epoch 12. c were quite small, with hind limbs that were 13. b functional for swimming and modest locomotion on 14. c land. These remains were found in river sediments, 15. d indicating an aquatic environment. 16. a b. The Middle Eocene Pakicetus and Protocetus 17. b lost their functional hind legs, leaving behind only 18. c small, vestigal limb bones. 19. b c. At the end of the Eocene Epoch, Basilosaurus 20. c reached lengths comparable to modern whales. 21. a d. In the Miocene Epoch, baleen whales diverged 22. b from toothed whales, and later in the Pliocene 23. d Epoch, the smaller toothed whales appeared. 24. c 2. The success of the grasses was due in part to their 25. b adaptation to a cooler, drier climate, and also their 26. a ability to spread while the upper part of the plant is 27. b constantly being chewed off. The durability of the grasses was due to their incorporation of minute True or False Items silica particles into their cell structures, and the challenge that grazing mammals had to overcome to 1. True. withstand the constant abrasion. Even today, the 2. False. Teleost fishes were the most common marine teeth of grazing animals eventually wear out from predators of the Cenozoic Era . the abrasive grasses. 3. True. 3. The extinction of the large mammal fauna at the 4. False. Mollusks were impacted little by the end of the Pleistocene specifically targeted Cretaceous Tertiary extinction event. mammals of large size. These mammals had been 5. False. Baleen whales are the largest animals that through several cycles of glaciation before, and have ever lived on Earth. had suffered no ill effects. What was different 6. True. about this last retreat of the glaciers? The Climate 7. False. The remaining reptiles were primarily Change hypothesis has a difficult time explaining diapsids. how this change could cause extinctions, as the 8. True. animals should be able to outrun the severe 9. False. Armadillo fossils have been found in conditions to locate more favorable ones. The Paleocene rocks. Overkill hypothesis may explain what really 10. False. Rodents are the most successful of all the happened better. Everywhere humans had been, mammal orders. the large mammals had already disappeared, 11. True. whether in Asia, Europe, or even Australia. The 12. True. fact that the large mammals of North America 13. False. Camels originated in North America during were the last to disappear has to do with the late the Oligocene, and then migrated into Asia before arrival of humans into this region, and with the their American forms became extinct. spear points that were left behind in the bones of 14. True. these animals. Some mammoths remained on 15. False. The large mammal fauna became extinct last Wrangel Island in Siberia until only 3500 years in North America, at about 8,000 years ago. ago, primarily because humans were unable to get 16. True. there until then. Humans probably did overkill 17. True. their large mammal contemporaries in a matter of 18. False. Homo sapiens probably coexisted with H. 4,000 years or so, and the large mammals such as erectus in southeast Asia, and with Neanderthals in buffalo that did survive were present in sufficient Europe. numbers to survive until this last century. 4. Investigations into the origin of humans are fraught with many problems, such as a lack of well- preserved fossils, a lack of established nearby

volcanic ash beds for radiometric age dates, a very 6. a incomplete fossil record, and a more limited set of 7. b depositional environments that are capable of 8. a preserving human remains. It is also difficult to 9. c establish whether scattered bones belong to one or 10. b many different individuals, whether they were 11. c contemporary of lived hundreds of years apart, and 12. a also what kind of differences should separate the 13. d sexes, different species, and even different genera 14. c of humans. Human populations also probably 15. b evolved at different rates in response to different 16. a environmental stresses, and as a result, some 17. d populations may have changed rapidly, whereas 18. c others may have changed very little. Interactions between populations of early humans and True or False Items predators, early humans and australopithecines, populations of modern humans with Homo erectus 1. False. The fossilized fish of the Green River populations, or populations of modern humans Formation were probably killed by the poisonous with Neanderthal peoples may also represent turnover of stratified lake waters. disaster for the less well-adapted group. All of 2. False. Planktonic foraminifera were small. Benthic these considerations make the interpretation of foraminifera grew to the size of a five-cent piece. human remains a difficult and challenging study. 3. True. What was once considered a very straightforward 4. True. evolutionary tree has become a very thorny bush 5. False. Diatryma was either a predator or a indeed. scavenger. 6. True. CHALLENGE TEST 7. False. Monotremes are the most primitive of today’s remaining mammal groups. Completion 8. True. 9. False. Cats, civets, and hyenas are felid mammals. 1. large lakes 10. True. 2. nummulitids 11. False Horses are odd-toed ungulates. 3. rudistid bivalves 12. True. 4. ammonites 13. True. 5. toothed whales 14. False. Prosimians have primitive features such as 6. Birds clawed fingers and elongated snouts. 7. Miocene Epoch 15. False. Hominoids include the lesser apes, great apes, 8. scavengers and humans. 9. eggs 16. True. 10. pouch 17. False. Humans today are so well connected by 11. reproduction transportation rates that potential differences could 12. moles not accumulate. New human species therefore 13. 40% would not form. 14. seals 15. toes 16. hunting 17. hominoid 18. hominid 19. Homo 20. australopithecine

Multiple-Choice Questions

1. b 2. d 3. d 4. c 5. d