236 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. Copyright © Houghton Mifflin Company. All rights reserved. 237 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. Copyright © Houghton Mifflin Company. All rights reserved. 238 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. Copyright © Houghton Mifflin Company. All rights reserved. 239 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