Chapter Presentation Visual Concepts Transparencies Standardized Test Prep
Introduction to Vertebrates Table of Contents Section 1 Vertebrates in the Sea and on Land Section 2 Terrestrial Vertebrates Section 3 Evolution of Primates Section 4 The Genus Homo
Section 1 Vertebrates in the Sea and on Land Objectives Identify the key characteristics of vertebrates. Describe two adaptations found in early fishes. Identify the relationship of fishes to amphibians. Summarize the key adaptations of amphibians for life on land.
Section 1 Vertebrates in the Sea and on Land Adaptations of Vertebrates Vertebrates are chordates with a backbone. They take their name from the individual segments, called vertebrae, that make up the backbone. In most vertebrates, the backbone completely replaces the notochord found in invertebrate chordates. The backbone provides support for and protects a dorsal nerve cord. It also provides a site for muscle attachment.
Section 1 Vertebrates in the Sea and on Land Vertebrate Skeleton (Cat)
Section 1 Vertebrates in the Sea and on Land Adaptations of Vertebrates, continued Vertebrates share a number of other characteristics, including segmentation, bilateral symmetry, and two pairs of jointed appendages, such as limbs or fins. The tissues of vertebrates compose organs. In turn, the organs compose organ systems. Vertebrate organ systems tend to be more complex than the organ systems found in invertebrates.
Section 1 Vertebrates in the Sea and on Land Major Vertebrate Organ Systems
Section 1 Vertebrates in the Sea and on Land The First Vertebrates The first chordates evolved about 550 million years ago. According to the fossil record, the first vertebrates appeared about 50 million years later. The first vertebrates were fishes. Unlike most of the fishes you are familiar with, the earliest fishes, called agnathans, had neither jaws nor paired fins. Within another 50 million years, jawless fishes had diversified into a great variety of species.
Section 1 Vertebrates in the Sea and on Land Evolutionary Relationships Among Chordates
Section 1 Vertebrates in the Sea and on Land Evolution of Fishes This phylogenetic tree shows the relationship of the early fishes to later fishes and amphibians.
Section 1 Vertebrates in the Sea and on Land Evolution of Fishes, continued About 430 million years ago, the acanthodians, or spiny fishes, appeared. Acanthodians had strong jaws with jagged, bony edges that served as teeth, enabling them to hold onto prey. Jaws are thought to have evolved from gill arch supports made of cartilage a lightweight, strong, flexible tissue. About 20 million years after the acanthodians appeared, the placoderms, jawed fishes with massive heads armored with bony plates, evolved.
Section 1 Vertebrates in the Sea and on Land Evolution of Jaws
Section 1 Vertebrates in the Sea and on Land Origin of Jaws
Section 1 Vertebrates in the Sea and on Land Evolution of Fishes, continued Sharks and Bony Fishes About 400 million years ago, sharks and bony fishes appeared. Most sharks and bony fishes have streamlined bodies that are well adapted for rapid movement through the water. Bony fishes have a skeleton made of bone, which is heavier and less flexible than cartilage. Bony fishes have a swim bladder, which compensates for this weight.
Section 1 Vertebrates in the Sea and on Land Swim Bladder in Bony Fish
Section 1 Vertebrates in the Sea and on Land Modern Fishes Today there are more fishes than any other group of vertebrates, both in terms of numbers of individuals and numbers of species. Today s fishes belong to one of three major groups: the agnathans, the cartilaginous fishes, and the bony fishes. Bony fishes make up about 95 percent of modern fish species. Because bony fishes are adapted to many different environments, they vary greatly in size, color, and shape.
Section 1 Vertebrates in the Sea and on Land Evolution of Amphibians The first group of vertebrates to live on land were the amphibians, which appeared about 370 million years ago. Amphibians probably evolved from a group of bony fishes called lobe-finned fishes. The pattern of bones in an amphibian s limbs bears a strong resemblance to that of a lobe-finned fish.
Section 1 Vertebrates in the Sea and on Land From Fin to Limb
Section 1 Vertebrates in the Sea and on Land Evolution of Amphibians, continued The Age of Amphibians Amphibians increased greatly in numbers during the Carboniferous period. During this time, which begins what is called the age of amphibians, the number of amphibian families increased from 14 to about 34. In the Permian period that followed, amphibians reached their greatest diversity, increasing to 40 families. By the middle Permian, 60 percent of all amphibian species were living in dry environments.
Section 1 Vertebrates in the Sea and on Land Evolution of Amphibians, continued Adaptations for Life on Land A number of major adaptations allowed some species to successfully invade land. 1. Legs. Legs support the body s weight as well as allow movement from place to place. 2. Lungs. On land, lungs carry out gas exchange. 3. Heart. Land animals tend to have higher metabolic rates than aquatic animals. The structure of the vertebrate heart allows oxygen to be delivered to the body efficiently.
Section 1 Vertebrates in the Sea and on Land Characteristics of Early Amphibians
Section 1 Vertebrates in the Sea and on Land Modern Amphibians All of today s amphibians are descendants of the amphibians that survived into the Jurassic period. They are found in aquatic and moist habitats throughout the temperate and tropical regions of the world. Frogs and toads make up the largest, and probably the most familiar, group of modern amphibians.
Section 2 Terrestrial Vertebrates Objectives Summarize why dinosaurs became the dominant land vertebrates. Contrast ectotherms with endotherms. Identify the dinosaurlike and the birdlike features of Archaeopteryx. Summarize why mammals replaced dinosaurs.
Section 2 Terrestrial Vertebrates Early Reptiles Fluid loss is a problem for all terrestrial animals, that is, animals that live on land. The adaptations that permitted amphibians to live on land further developed in reptiles. Two very important adaptations for terrestrial life evolved in reptiles. Reptiles were the first animals to have skin and eggs that are both almost watertight, and they differ from amphibians in this respect.
Section 2 Terrestrial Vertebrates Early Reptiles, continued This phylogenetic tree shows the presumed relationship of early reptiles to the animals that evolved from them.
Section 2 Terrestrial Vertebrates Evolution of Dinosaurs Beginning about 235 million years ago, dinosaurs dominated life on land for roughly 150 million years. They evolved from the thecodonts, an extinct group of crocodile-like reptiles. One factor that affected dinosaur evolution was the movement of the continents, which radically altered Earth s climate. When the dinosaurs first appeared, all of Earth s landmasses were joined in a single supercontinent called Pangaea.
Section 2 Terrestrial Vertebrates Breakup of Pangaea
Section 2 Terrestrial Vertebrates Continental Drift (Pangaea)
Section 2 Terrestrial Vertebrates Evolution of Dinosaurs, continued Triassic Dinosaurs By the end of the Triassic period, small, carnivorous dinosaurs were very common and had largely replaced the thecodonts. There are at least three reasons why dinosaurs were so successful: 1. Legs positioned directly under the body provided good support for the dinosaur s body weight, enabling dinosaurs to be faster and more agile runners than the thecodonts. 2. Dinosaurs were well adapted to the dry conditions found in Pangaea during the late Triassic period. 3. At the end of the Triassic period a large meteorite struck northeastern Canada. Thecodonts and many other species became extinct, but the dinosaurs survived.
Section 2 Terrestrial Vertebrates Evolution of Dinosaurs, continued The Jurassic Period The Golden Age of Dinosaurs The Jurassic period is considered the golden age of dinosaurs because of the variety and abundance of dinosaurs that lived during this time. They included the largest land animals of all time, the sauropods. Sauropods were the dominant herbivores of the Jurassic period. By the late Jurassic period, a new type of dinosaur had evolved. These dinosaurs, the carnivorous theropods, stood on two powerful legs.
Section 2 Terrestrial Vertebrates Evolution of Dinosaurs, continued Were Dinosaurs Warmblooded? Ectothermic animals, such as today s reptiles, have metabolisms that are too slow to produce enough heat to warm their bodies. Mammals and birds are endothermic animals. They maintain a high, constant body temperature by producing heat internally. For a long time it was thought that dinosaurs were ectotherms. However, new evidence indicates that at least some dinosaurs were endotherms.
Section 2 Terrestrial Vertebrates Comparing Endotherms and Ectotherms
Section 2 Terrestrial Vertebrates Evolution of Dinosaurs, continued The Cretaceous Extinction 65 million years ago, all dinosaurs abruptly disappeared from the fossil record. Most scientists now agree that the major contributing cause was the impact on Earth of one or more meteorites or asteroids. Such an impact would have thrown large amounts of material from Earth s surface into the atmosphere. This would have blocked sunlight and created a prolonged cold period.
Section 2 Terrestrial Vertebrates Mass Extinction
Section 2 Terrestrial Vertebrates Evolution of Birds The earliest known bird is Archaeopteryx. Archaeopteryx was about the size of a crow and shared many features with small theropods. Archaeopteryx had a dinosaurlike skeleton, but birdlike wings and feathers. By the early Cretaceous period, only 15 million years after Archaeopteryx lived, a variety of birds with many of the features of modern birds had evolved.
Section 2 Terrestrial Vertebrates Modern Birds There are more species of birds than of any other terrestrial vertebrate. Birds live in a wide variety of environments and differ greatly in appearance. While most birds have wings and can fly, some birds such as the ostrich have wings and do not fly. Most birds consume small, energy-rich meals of fruits, seeds, worms, or insects.
Section 2 Terrestrial Vertebrates Modern Reptiles Of the 16 orders of reptiles known to have existed, only four remain today. The turtles have the most ancient origins and have changed very little since before the time of the dinosaurs. The vast majority of living reptiles belong to the second group to evolve snakes and lizards. Tuataras belong to the third group. The fourth line of living reptiles crocodiles and their relatives, including the familiar alligators appeared on Earth much later than the first three groups.
Section 2 Terrestrial Vertebrates Evolution of Mammals The first mammals appeared about 220 million years ago, just as the dinosaurs were evolving from thecodonts. It is most likely that mammals were descendants of the therapsids, an extinct order of reptiles that were probably endotherms. Mammals are the only vertebrates that have fur and mammary glands.
Section 2 Terrestrial Vertebrates Therapsids
Section 2 Terrestrial Vertebrates Evolution of Mammals, continued Early mammals, such as Eozostrodon, were small about the size of mice. They were insect-eating tree dwellers that were active at night.
Section 2 Terrestrial Vertebrates Characteristics of Early Mammals
Section 2 Terrestrial Vertebrates Evolution of Mammals, continued Diversification of Mammals In the Tertiary period, mammals rapidly diversified, taking over many of the ecological roles once dominated by dinosaurs. The largest land mammals reached their peak during the last ice age (about 2 million to 10,000 years ago). Today, there are more than 4,500 species of mammals, and they inhabit virtually every habitat on Earth. They are found in jungles, deserts, and on polar ice.
Section 2 Terrestrial Vertebrates Modern Mammals Modern mammals other than monotremes show one of two patterns of development. 1. Marsupials. Marsupial young are born at a very immature stage and complete their development in their mother s pouch (called a marsupium). 2. Placentals. Placental mammals develop within their mother s body and are nourished by an organ called the placenta.
Section 3 Evolution of Primates Objectives Name two unique features of primates. Contrast prosimians with monkeys. Distinguish monkeys from apes. Describe the evolutionary relationship between humans and apes. Identify the evidence that indicates human ancestors walked upright before their brains enlarged.
Section 3 Evolution of Primates Characteristics of Primates A primate is a member of the mammalian order Primates, which includes prosimians, monkeys, apes, and humans. The first primates had: 1. Grasping hands and feet 2. Forward orientation of the eyes
Section 3 Evolution of Primates Types of Primates
Section 3 Evolution of Primates Characteristics of Primates, continued Prosimians According to the fossil record, the modern primates that most closely resemble early primates are the prosimians. A prosimian is a member of a group of mostly nightactive primates that live in trees. Modern prosimians include lorises, lemurs, and tarsiers.
Section 3 Evolution of Primates Nonhuman Primates About 36 million years ago, a revolution occurred in how primates live. Many primate species became diurnal. Diurnal animals are active during the day, and they sleep at night. The evolution of a diurnal pattern gave primates more opportunities to feed and enabled them to better detect predators.
Section 3 Evolution of Primates Comparing Diurnal and Nocturnal
Section 3 Evolution of Primates Nonhuman Primates, continued Monkeys Feeding mainly on fruits and leaves, monkeys were among the first primates to have opposable thumbs. An opposable thumb such as your own stands out at an angle from the other fingers and can be bent inward toward them to hold an object. This gives the hand a greatly increased level of ability to manipulate objects.
Section 3 Evolution of Primates Nonhuman Primates, continued Apes Apes, which share a common ancestor with monkeys, first appeared about 30 million years ago. Modern apes include gibbons, orangutans, gorillas, and chimpanzees. Apes have larger brains with respect to their body size than monkeys, and none of the apes have tails.
Section 3 Evolution of Primates Nonhuman Primates, continued This phylogenetic tree represents the theoretical evolutionary relationships between modern apes and humans.
Section 3 Evolution of Primates Clues to Human Ancestry
Section 3 Evolution of Primates Early Hominids Hominds are primates that walk upright on two legs. Hominids are members of the group that led to the evolution of humans. According to the fossil record, hominids first appeared on Earth about 5 million to 7 million years ago.
Section 3 Evolution of Primates Hominid
Section 3 Evolution of Primates Comparing Bipedal and Quadrupedal Movement
Section 3 Evolution of Primates Early Hominids, continued Australopithecines The early hominids best represented by fossil finds belong to the group known as australopithecines. Their fossil remains indicate that australopithecines walked upright on two legs; thus they are classified as hominids. The brains of australopithecines had a slightly greater volume, relative to body weight, than the brain of an ape.
Section 3 Evolution of Primates Comparison of Gorilla and Australopithecine Skeletons
Section 3 Evolution of Primates Comparing Gorillas and Australopithecine Skeletons
Section 3 Evolution of Primates Early Hominids, continued Other Early Hominids In the past few years, scientists have discovered fossils of hominids that indicate that the hominid line extends back past 6 million years. Over the last 6 million years, a variety of different hominids have existed, with more than one species living at one time. As new fossils are found, our picture of the root of the human phylogenetic tree may come into sharper focus.
Section 3 Evolution of Primates Hominids in the Fossil Record
Section 4 The Genus Homo Objectives Compare H. habilis with australopithecines. Describe the characteristics of Homo erectus. Describe the evidence that suggests that H. sapiens evolved in Africa. Compare Neanderthals with modern humans.
Section 4 The Genus Homo Early Members of the Human Genus
Section 4 The Genus Homo Homo habilis Our genus, Homo, is composed of at least three species. Of these three, modern humans, Homo sapiens sapiens, is the only surviving species. The first members of the genus Homo appeared on Earth more than 2 million years ago. Because of its association with tools, this hominid was named Homo habilis. The Latin word homo means man, and the Latin word habilis means handy. Fossils indicated that Homo habilis lived in Africa for about 500,000 years and then became extinct.
Section 4 The Genus Homo Homo erectus Homo erectus was larger than Homo habilis about 1.5 m (5 ft) tall. Homo erectus also had a large brain of about 1,000 cm 3 (60 in. 3 ). Homo erectus evolved in Africa and migrated into Asia and Europe. Homo erectus survived for more than 1 million years. The species disappeared about 200,000 years ago, as early modern humans emerged.
Section 4 The Genus Homo Theory of Hominid Migration
Section 4 The Genus Homo Homo sapiens Homo sapiens is the only surviving species of the genus Homo. The name Homo sapiens is from the Latin homo, meaning man, and sapiens, meaning wise. Homo sapiens is a newcomer to the hominid family. Early Homo sapiens left behind many fossils and artifacts, including the first known paintings.
Section 4 The Genus Homo Homo sapiens, continued African Origins? In the past, some scientists proposed that independent Homo erectus groups living in Africa, Europe, and Asia interbred and that Homo sapiens thus arose as a new species at the same time all over Earth. Most scientists, however, argue that Homo sapiens appeared in one place (Africa) and then migrated to Europe and Asia, where the species gradually replaced Homo erectus.
Section 4 The Genus Homo Homo sapiens, continued Homo sapiens in Europe Members of the species Homo sapiens, called Neanderthals, first appeared in Europe about 130,000 years ago. The Neanderthals were short and powerfully built. Neanderthals became more and more abundant in Europe and Asia, and by 70,000 years ago, they had become fairly common. Neanderthals were the first hominids to show evidence of abstract thinking.
Section 4 The Genus Homo Neanderthals
Section 4 The Genus Homo Homo sapiens, continued Modern Homo sapiens About 34,000 years ago, the European Neanderthals were abruptly replaced by Homo sapiens of modern appearance. These early humans are thought to have evolved first in Africa and then migrated to Europe and Asia. Early modern humans lived by hunting. They had complex patterns of social organization, and they probably used language.
Standardized Test Prep Multiple Choice The drawings below show two extinct animals. Use the drawings to answer questions 1 3.
Standardized Test Prep Multiple Choice, continued 1. The colored bones in the drawings are examples of A. gill arches. B. vertebrae. C. homologous structures. D. vestigial structures.
Standardized Test Prep Multiple Choice, continued 1. The colored bones in the drawings are examples of A. gill arches. B. vertebrae. C. homologous structures. D. vestigial structures.
Standardized Test Prep Multiple Choice, continued 2. Which statement about the evolution of these animals is most likely correct? F. The lobe-finned fish evolved from the amphibian. G. The amphibian evolved from the lobe-finned fish. H. Both animals evolved from an earlier species of amphibian. J. Both animals evolved from different, unrelated ancestors.
Standardized Test Prep Multiple Choice, continued 2. Which statement about the evolution of these animals is most likely correct? F. The lobe-finned fish evolved from the amphibian. G. The amphibian evolved from the lobe-finned fish. H. Both animals evolved from an earlier species of amphibian. J. Both animals evolved from different, unrelated ancestors.
Standardized Test Prep Multiple Choice, continued 3. These animals belong to the same A. family. B. order. C. class. D. phylum.
Standardized Test Prep Multiple Choice, continued 3. These animals belong to the same A. family. B. order. C. class. D. phylum.