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CHAPTER Big into different groups. traits, butother, specialized characteristics classify these ONL 26.4 26.2 26.3 26 26.1 Online Bi Unit 8:Animals ■■ ■■ ■■ ■■ ■■ ■■ Identifying Features: Hair Form andFunction ofTeeth Migration and Range The Parts ofanEgg A ’s Airframe QuickLab I I N dea

E R A Labs Ch D

eptiles mniot ata Comparing Fe oo , birds, andmammals all share similar at A Closer Look o si A l o n nalysis es gy g 7A, 7B, 10A G athers

raphs 7A, 7B, 8C, 10A HMDScience.com 7B, 10A 7A, 7B, 7D, 8B, 8C,10A 2G ■■ ■■ ■■ Video Lab Video Lab Organisms The Effect ofTemperature onCold-Blooded

Mammalian Char Bird acteristics

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Q Is this a monkey or a ? The large eyes and ears of this eastern make it an excellent nocturnal hunter. These unusual mammals are and are closely related to modern monkeys. About the same size as a kitten, a tarsier has strong hind legs similar to those of . The tarsier’s eyes cannot move but it has a full range of view because it can rotate its head almost 360 degrees.

READING Toolbox This reading tool can help you learn the material in the following pages.

USING LANGUAGE Your Turn Word Problems A good way to begin solving a word Refer to the word problem example to answer the problem is to figure out what it is asking for. For example: questions below. A pregnant whale weighs 136,000 kg. How much does 1. After giving birth to the calf, would the mother whale she weigh after giving birth if her calf weighs 2700 kg? weigh more or less than she did before giving birth? The problem asks for the weight of the mother whale, which 2. How would you solve the word problem example? is different from what it was at the start of the problem.

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26.1 Amniotes

2G, 7B, 10A key concept Reptiles, birds, and mammals are amniotes. MAIN IDEAS VOCABULARY develop in a fluid-filled sac. pulmonary circuit and circulation differ among amniotes. systemic circuit Amniotes can be ectothermic or endothermic. Connect to Your World When you were about nine weeks into your development, you had a mass of about 2G analyze, evaluate, make inferences, and predict trends from 2 grams and measured about 18 millimeters long, roughly the size of a dime. Over the data; 7B analyze and evaluate next seven months, you grew and developed while living safely inside a fluid-filled scientific explanations concerning any data of sudden appearance, membrane, or . There are many types of amniotes, but each of them, like stasis, and sequential of you, begins life inside an amniotic sac. groups in the record; 10A describe the interactions that occur among systems that perform the functions of regulation, nutrient absorption, , and MAIN IDEA defense from injury or illness in animals Amniote embryos develop in a fluid-filled sac. Reptiles, birds, and mammals are all amniotes. Recall that amniotes develop inside a membraneous sac. This sac contains everything an embryonic verte- brate needs to grow and prepare for the world outside. In some amniotes, the sac is contained inside the mother’s body. In other amniotes, a tough outer shell protects embryos as they develop outside of the mother. This shell is semipermeable, which means that it allows gases such as and carbon dioxide to pass through but prevents the from drying out by holding water inside. FIGURE 1.1 Amniotic An egg is a completely self-sustaining container that provides enough energy and nutrients to Inside the shell of an amniotic egg, four membranes enable the embryo to mature. The illustration in perform specific functions during development of Figure 1.1 shows the different membranes found the embryo. inside an amniotic egg. The egg you may have Holds eaten for breakfast this morning was formed with Embryo waste materials as the embryo grows all of the necessary membranes and nutrient stores Protects to support a chicken embryo. But because the egg and surrounds the embryo was never fertilized, the genetic composition of the egg remained haploid and did not develop into an embryo. The development of the amniotic egg was an important adaptation because it allowed to reproduce on land. Without the self-contained source of energy and water, an egg needed to Allows sac Contains the develop in water or else the embryo would dry out. with outside environment nutrient supply for the growing embryo Predict What happens when all of the resources that are stored inside the egg are used?

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(tl) ©Aaron Shimer; (tr) ©Cyril Ruoso/JH Editorial/Minden Pictures differ among amniotes. among differ Anatomy and circulation

upright stance and to run breathe at same the time. forneeded and walking . Adiaphragm enables amniotes with an to expand chest the cavity and force air into , the separated muscles the and The evolutionwalk run. of diaphragm, the an independent muscle used separates muscles the the to uses breathe from muscles the it to uses side to side. An upright stance than less uses asprawling energy one. It also legs swing back and forth like pendulums, and notfrom its does wiggle body underneath its and body hold it far away from ground. the When it its walks, of vessels blood are pulmonary the and systemic circuits. separate, amniotes more energy can conserve effectively. The two circuits nutrients to tissues and organs. thatheart moves through blood acomplex system of vessels blood to deliver ment of many of types circulatory systems. amniotes All have acentralized efficienthighly ways of delivering oxygen. this to Thisled develop- the need growth. To get energy, this tissues their demanded more and energy needed As amniotes evolved, required bodies their more for energy movement and Circulation that of the in The first amniotes inasprawl walked similar to Anatomy circulation. in many differences inanatomy and blood different shapes body and sizes, resulting time, amniotesOver have evolved many stance. The cat in ever, some reptiles have adaptations that allow to them breathe running. while animals with asprawling stance cannot and run breathe at same the time. How- to side with each step. same muscles these inflate Because lungs, the also many tractions make lizard’s the sway body from side help propel forward, body the and con their - elbows and bent. knees Muscles around the out on either side of its body. It with its walks everyday functionseveryday and behavior. . of As an differences organism’s these you efficiency see, the affect will • • MAIN IDEA MAIN

The a All Amn The dif of body. the The lungs, and oxygen-rich back to . the blood

systemic circuit pulmonary circuit mniotes have two circuits of circuits vessels.the blood Because are iotes such as mammals, , and birds evolved amore upright ferences inamniote circulatory systems evolved over millions of

F F IGURE IGURE 7 b moves oxygen-rich from blood to heart rest the the 1.2 1.2. moves oxygen-poor from blood to heart the the has straighter limbs than lizard. the Its legs are Alizard’s legs stick Chapter 26:ACloser Lookat Amniotes F styl walkers. and more efficientfor upright cal features make breathing easier upright stance ofacat. Anatomi- dragon isvery different from the IGURE systemic blood circuits. notes onthepulmonaryand Use atwo-column to chart take T umnr ici Systemic Circuit Pulmonary Circuit e illustrated by thisKomodo A K READING READING ING NO 1.2

The sprawling walking T ES TOOLB o x

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CONNECT TO Like , reptiles have a three-chambered heart. A ’s heart has two atria and one , as shown in FIGURE 1.3. One collects The heart is a muscle for oxygen-poor blood from the body. The other collects oxygen-rich blood from pumping blood through the the lungs. Both atria send blood into the ventricle, which pumps blood into body. It has two different the pulmonary and systemic circuits. This unique anatomy lets these animals chambers. The right and left atria temporarily “turn off” their lungs. Like amphibians, amniotes such as collect blood from the body and lungs, and the right and left and do not breathe continuously. Remember that sprawling amniotes ventricles pump blood to the stop breathing when they run. Others spend a lot of time under water. In lungs and body. You will learn either case, a single ventricle can divert blood away from the lungs when the more about the heart in the chapter Respiratory and animal is not using them. This strategy lets these animals adjust blood flow Circulatory Systems. in response to their oxygen needs. Mammals and birds have a four-chambered heart. As you can see in FIGURE 1.3, four-chambered have two atria and two ventricles. This anatomy keeps oxygen-poor and oxygen-rich blood separate, but it cannot shift blood away from the lungs when the animal is not breathing. Keeping oxygen-rich and oxygen-poor blood separate effectively increases the flow of oxygen-rich blood to tissues. This adaptation gives these active animals a large and constant supply of oxygen. The development of the four-chambered heart allowed for an increase in energy use and eventually gave organisms increased control over their body temperature. Infer Many reptiles are ambush predators, hiding and waiting for prey to come to them as opposed to actively hunting. Explain how this behavior may be related to their circulatory system.

FIGURE 1.3 Amniote Hearts The heart, the pump that moves blood around an organism’s Oxygen-poor blood body, has developed differently in reptiles and mammals. Oxygen-rich blood

Three-Chambered Heart Four-Chambered Heart Reptile hearts have three chambers. A septum that only par- Birds and mammals have a heart divided into four chambers, tially divides the heart helps direct oxygen-rich and oxygen- which keeps oxygen-rich and oxygen-poor blood separate. poor blood. to body from lungs to body from lungs to body right from body atrium to lungs

left atrium right left atrium to lungs atrium

right septum from body ventricle left ventricle ventricle septum

Contrast How do differences in the septum affect blood flow in these hearts?

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(t) ©David R. Parks (http://www.mobot.org/mobot/madagascar); (b) ©Flip Nicklin/Minden Pictures Amniotes can be ectothermic or endothermic. or canectothermic be Amniotes

or panting. Many , such in as polar the bear heat.extra If get hot, too may they they down cool by sweating get cold, too they when contracting muscles their to generate temperature relatively constant of all time. the may They shiver regulate metabolic their activity inways that keep body their heat to keep tissues their warm. More specifically, endotherms F F stead, scientists term the use and amphibians, is not blood their because cold. actually In- or alizard. This not term does accurately reptiles describe heat indifferent ways. ment and release heat as abyproduct of . But animals all manage quickly and more often. living All organisms absorb heat from environ- the ents to its tissues. It move can also faster its because muscles contract more temperatures. Awarm amniote digests faster and can more send nutri- that up chemical the speed reactions inside cells are more active at higher organisms, all Like amniotes are more are active they when warm. are but time the active all must eat more than eat. itwhen is cold but on can than survive less endotherms. food Endotherms onsurvive much less meat than alion can. In short, ectotherms are less active example, and are large both predators, but can acrocodile quickly and require more ATP, which requires an animal to eat more. For temperaturebody and amount the of it Warm energy uses. tissues work strategies for managing use. There energy an is atrade-offbetween animal’s cells, or , which helps control them heat loss. therm. organismsthese more accurately, scientists term endo the use other as “warm-blooded.” mammals described But to describe environmentthe is relatively cool. Large ectotherms, such can as stay crocodiles, warm even when animal is massive enough, along take it will to time down. cool harder shedding time heat than animals. small If an ectothermic outside temperatures climb Large high. too animals have a are cold. Similarly, lizards move into shady when behavior. For example, many reptiles, such as the in temperaturesbody inawarm environment than one. inacool with temperature the of environment. their have They higher environment. organisms’ These temperature body fluctuates temperatures body whose are determined by surrounding their MAIN IDEA MAIN IGURE IGURE You m You c On th Ect 1.4, 1.4,

otherms regulate temperature body their through their Endotherms an of think endotherms and ectotherms as having two different e other hand, you have probably heard and are covered with insulation form inthe of hair, fat bask insunny places to warm tissues their they when ay have heard term “cold-blooded” the a to describe

are organisms that own their use metabolic 10A ectotherms to refer to organisms - Chapter 26:ACloser Lookat Amniotes even incold environments. tively constant body temperature polar bear can maintain arela- Endotherms suchasthis light. temperature by baskinginsun- a chameleon incr Internal BodyTemperatureInternal GO ONLINE F IGURE HMDScience.com 1.4

As anectotherm, eases itsbody

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Choosing Graphs Table 1. Body mass and food intake Choosing an appropriate type of Organism Mass (kg) Food Intake (kg/yr) graph to represent data collected in Nile 150 750 an experiment is an important part of the scientific process. Grey kangaroo 45 1108 45 250 The table to the right contains data that show the differences in energy Koala 8 252 requirements for endotherms and 8 93 ectotherms. Despite having similar sizes, endotherms and ectotherms Source: Nagy, K.A. Nutrition Abstracts and Reviews Series B:71. use energy in different ways and therefore require different amounts of food.

1. Graph Choose and construct one graph that can represent both sets of data. 2. Analyze Explain why there is a difference in energy requirements between endotherms and ectotherms.

The ability to regulate their own temperature served as an important function in the early stages of endotherm . This adaptation gave endotherms a distinct advantage over ectotherms as Earth’s climate changed millions of years ago. Because they could stay warm in colder weather, endo- therms were able to exploit resources that the ectotherms could not. Many scientists believe that the ability to regulate their own body temperature allowed endotherms to survive the catastrophic events that led to the of dinosaurs. Analyze As you move away from Earth’s equator into colder latitudes, why are there fewer ectotherms and more endotherms?

Self-check Online HMDScience.com 26.1 Formative Assessment go online Reviewing Main Ideas Critical thinking CONNECT TO 1. How did the development of an 4. Infer A 30-gram shrew will die if Survivorship amniotic egg allow vertebrates to it cannot eat for a few hours. A 6. When are laid by a reproduce on land? 30-gram thrives on a few species of reptile or bird, 2. How do anatomy and circulation crickets every other day. Why might they generally stay in a nest differ among amniotes? shrews need food more often? that is closely guarded by a mother. How does this 3. What is the difference between an 5. Compare Illustrate the path of blood behavior affect the chances endotherm and an ectotherm? through a three-chambered heart when the animal is breathing. Show for offspring to survive to how the pathway changes when the adulthood? What type of animal is not breathing. 10A survivorship strategy does this represent? 7D

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©Michael Maconachie/Alamy Images FIGURE 2.1 means “creeping.” the Latin word, reptilis, which The namereptile comes from VOCABULARY viviparous oviparous reptile VOCABULARY to maintain itsbodytemperature. dra animals defense from injuryorillness in absorption, reproduction, and ofregulation,the functions nutrient occur amongsystems that perform 7 molecular, anddevelopmental; homologies, includinganatomical, fossil record, biogeography, and among groups isprovided by the how evidenc 10 fungi, plants, andanimals; including archaea, bacteria, protists, characteristics oftaxonomic groups, fossil record; 8Ccompare sequential nature ofgroups inthe sudden appearance, stasis, and explanations concerning anydata of B A R anal gon uses energy from sunlight describe theint E ADI yze andevaluate scientific 7 A 26.2 analyze andevaluate

N e ofcommon ancestry This eastern water G TOOLB 7 eractions that A , 7b, 8C, 10a Reptiles o x Reptiles are adiverse groupofamniotes. reptiles unique? andeatskills, itsprey way inthesame that itslarger cousins do.What makes in length andmay never compare to acrocodile asathreat to humans,butithunts, is adauntingpredator. Theeastern water dragon may only grow to 80centimeters speed ofalmost 20kilometers perhour, andstrong jaws filled withsharpteeth. It Basking onthesunnybanksofriver, thelizard may look slow, butithasatop Connect to Your World ke Analyze

y normal body functions.normal body or platesscales that absorb and energy help contain heat to maintain needed sunbathing, to absorb from energy sunlight. In addition, reptiles have dry the reptiles—havethe thrivedfor millions of years. of Earth’s plant and animal One group species. of organisms that survived— About 200million years ago, amass extinction resulted loss inthe of many water dragon in ture changes on surrounding the based environment. Similar to eastern the But despite differences, these reptiles all share afew similarities. reptileEach group has adapted different features that allow it successful. to be water. shaped The oddly and turtles homes their on carry backs. their reptilesonno legs. Other swiftly land run or spend much of inthe time their are two ways that reptile develop. eggs thategg allows an embryonic reptile to develop before fully it isThere born. covered with atough outer shell. are or covered plates scales with dry and reproduce by laying amniotic eggs • • MAI MAI


Viviparous Oviparous All li All The s of development and give to birth live offspring. Unli develop completely independent of adult the reptile. There are four moderngroups ofreptiles. Reptiles have beenevolving for ofyears. millions Reptiles are adiverse group ofamniotes. N n N

ID c What advantages does a self-sustainingdoes advantages What egg give reptiles? ID ke amphibians, reptiles produce acompletely self-sustaining, amniotic ept ving reptiles are that ectotherms. an Recall ectotherm’s tempera- body hapes and sizes ofwidely. reptiles modern vary Some reptiles have E E A AS

Reptiles were thefirstamniotes. reptiles depositinto eggs their an externalnest, and eggs the reptiles hold insidethrough eggs the body duration their the FIGURE 2.1, 10a

many reptiles spend agreat of deal basking, time or Reptiles Chapter 26:ACloser Lookat Amniotes are ectotherms that

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MAIN IDEA 7b Reptiles have been evolving for millions of years. Fossil evidence suggests that reptiles began to emerge from the water during the late era, almost 350 million years ago. They became the domi- FIGURE 2.2 Turtles and tortoises are . Aside from the nant during the era. holes for eyes and , this of a modern has no , Anapsids, and temporal holes. Scientists discovered that, over time, amniotes evolved into three different groups. This discovery was based on temporal holes that are found on the sides of the amniote skull. Synapsids Reptiles that had one hole in each temporal region were synapsids. The synapsids eventually gave rise to modern mammals. Anapsids Reptiles that have without temporal holes are anapsids. Scien- tists do not know why skull holes are absent in anapsids. Some think that they may still have the same skull anatomy as the first amniotes or that they may have lost skull holes through natural selection. The anapsids of today are turtles and tortoises, with skulls similar to the one shown in FIGURE 2.2. Diapsids Reptiles that have two holes in each temporal region, one Amniote Skull Types above the other, are diapsids. skulls came about as reptiles Skull pairs of Example began to colonize land. For the next 200 million years, diapsid type temporal reptiles ruled Earth. Eventually, this group gave rise to many of the holes modern reptiles and birds of today. 0 turtles Skull holes may have started out as a weight-reducing adaptation. 1 mammals Less bone would have made the skull lighter and easier to move and Diapsid 2 birds, lizards, given more space for muscle attachments, allowing jaw muscles crocodilians to get larger. The in FIGURE 2.3 shows how the ancient and now extinct groups of reptiles may have evolved. Diversity of Extinct Amniotes were synapsids that first appeared during the late period. This group included both carnivores and herbivores. Some pelyco- saurs had a distinctive “sail-back” made of elongated vertebral spines. Most pelycosaurs died in a mass extinction 245 million years ago, but some of their descendants later gave rise to the mammals. were some of the first diapsid reptiles. An ’s sleek IDEO V CLIP body, flipper-shaped limbs, and fleshy dorsal fin were similar to those of the modern day dolphin. Ichthyosaurs swam by beating their fishlike back HMDScience.com and forth in the water, and their peglike teeth suggest that they ate . Fossil go online evidence indicates that ichthyosaurs first appeared about 250 million years ago Reptile Evolution and went extinct about 90 million years ago. Plesiosaurs were some of the strangest prehistoric marine reptiles. They “flew” through the water like lions, using four limbs like elongated flippers. Some plesiosaurs had small heads and very long necks, which were likely used to help them catch fish. Others had short necks and long heads and probably chased and caught larger prey. show the plesiosaurs first appeared

around 220 million years ago and then died out around 80 million years ago. Inc. Anatomical Preparations, Academy of Sciences Department Ornithology and /Valley ©

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FIGURE 2.3 phylogenetic Tree of Reptiles The diversification of ancient reptiles eventually led to the evolution of modern animals.

lizards, , Millions of mammals turtles and crocodilians birds years ago

Cenozoic 50 dinosaurs plesiosaurs ichthyosaurs 100


Jurassic 200

Triassic pelycosaurs 250


Carboniferous anapsids diapsids 350

synapsids reptiles

Analyze Are there any diapsid mammals? Explain your answer using the diagram.

Dinosaurs were the second great radiation of the amniote family. They CONNECT TO appeared 230 million years ago and were the dominant land vertebrates for the Phylogeny next 150 million years. Many kinds of dinosaurs evolved during that time. Recall from the chapter The Tree Herbivorous species included huge sauropods, tanklike ceratopsians, and of Life that a phylogeny is a type duck-billed dinosaurs. They were hunted by carnivorous theropod dinosaurs, of evolutionary tree that which eventually gave rise to birds. All of the nonavian, or walking, dinosaurs illustrates how different species are related to each other. The went extinct 65 million years ago. relationships between modern Pterosaurs were the first vertebrates to evolve powered flight. Their wings animals and ancient reptiles help consisted of supported by an extremely elongated fourth finger. The scientists understand evolution. earliest species, from the end of the , were small animals with long tails. Later species, such as , lost their tails and grew as large as small airplanes. Recent fossils show that pterosaurs may have been covered with hair, suggesting that they were endothermic. They went extinct at the end of the Cretaceous along with the dinosaurs. Apply How did the discovery of temporal skull holes help scientists determine phylogeny of amniotes? 7b

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MAIN IDEA 7A, 7b, 8C There are four modern groups of reptiles. Web Of all the reptiles that evolved during the Mesozoic era, only four groups are alive today: turtles, sphenodonts, snakes and lizards, and crocodilians. HMDScience.com GO ONLINE Turtles Sea Turtles There are about 200 living species of turtles today. Turtles, tortoises, and terrapins are the only remaining anapsid group of amniotes. The distinctive shape of a turtle is actually a bony shell that encases the reptile’s body. The domed back of a turtle’s shell is called the carapace, while the smooth ventral part is called the plastron. This shell is covered with tough, flattened plates made of that are fused to the turtle’s cage and vertebrae. Many turtles can pull their head and limbs into the shell for protection. Turtles are toothless and have sharp, horny . Most turtles are omnivo- rous—they eat plants as well as animals. They are found in terrestrial, ­fresh-water, and marine environments. Fully terrestrial turtles are called tortoises. They have high domed shells and thick stumpy limbs. Freshwater turtles have flatter shells. Some species have lost the bone in their shells to FIGURE 2.4 Sea turtles live in tropical ocean waters all over the become “soft shell” turtles. The in FIGURE 2.4, like most marine world. turtles, has forelimbs that are large flippers that let it “” underwater. Sphenodonts The only living sphenodonts are two species of that live on a few small FIGURE 2.5 Snakes and lizards islands off the coast of . They are closely related to lizards and protrude a forked tongue to col- snakes, and look similar to a spiny . Tuataras have primitive characteris- lect tiny molecules out of the air. tics, such as a diapsid skull and an eyespot in the center of their head. These molecules are interpreted by the Jacobson’s to inform the reptile about its surroundings. Snakes and Lizards Snakes and lizards are very closely related and share a number of features. Snakes and lizards all shed their skin at regular intervals. They also have flexible skulls that let them capture and swallow prey larger than their head. All snakes and lizards use a highly developed organ that allows them to “taste” the air. As shown in FIGURE 2.5, when a snake or lizard flicks its forked tongue out of its , the tongue collects particles out of the air. Particles are interpreted by a sensory receptor called the Jacobson’s organ, which is found in the top of the reptile’s mouth. This organ allows lizards and snakes to locate prey and avoid predators. brain Jacobson’s organ Most lizards are carnivorous. Small species hunt insects, but large species such as the Komodo dragon prey on mammals. Some species, such as , are strict herbivores. Snakes are a group of legless lizards. All snakes are predators. Some snakes kill their prey by constriction, wrapping their body around their prey and squeezing. Others use poisons that are injected into their prey through modified teeth.

tongue (t) ©Gerard Soury/OSF/Photolibrary; (b) ©Joe McDonald/Corbis

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FIGURE 2.6 Reptile Anatomy The unique features of reptiles include a three-chambered heart and a single reproductive and excretory opening called a . reproductive organ ovary brain stomach



heart bladder Apply How does reptile anatomy prevent the organism from running and breathing at the same time?

Crocodilians There are 23 species of crocodilians, including , crocodiles, and . They are all semiaquatic predators that live in swamps and rivers in the tropics and subtropics. They are ambush predators, waiting underwater to surprise other animals. Their sprawling resting posture makes them look slow, but they are capable of lifting up their bodies and running at up to 27 kilometers per hour (17 mph). Crocodilians are one of two groups of that survived the mass reptile extinction 65 million years ago. Archosaurs were a large group of reptiles that included crocodiles, dinosaurs, and modern-day birds. Based on molecular evidence, crocodilians are actually more closely related to birds than they are to lizards and snakes. Many of the body shapes and structures of ancient crocodilians are similar to the features of modern crocodilians. Summarize What features do all reptiles share? 8C

Self-check Online HMDScience.com 26.2 Formative Assessment go online Reviewing Main Ideas Critical thinking CONNECT TO 1. How is a viviparous reptile different 4. Classify You find a fossil of a reptile Amphibians from an oviparous reptile? that has a long neck and four long 6. Amniotes emerge from 2. What are the major groups of extinct flippers for limbs. It is located in their shell fully developed. reptiles? marine sediments. To which group of Amphibians must go through ancient reptiles could it belong? to reach 3. What features do modern reptiles their adult form. What is share? 8C 5. Describe What traits help reptiles regulate their body temperature? the advantage of direct 10a development for amniotes?

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26.3 Birds

7a, 7b, 10a key concept Birds have many adaptations for flight. MAIN IDEAS VOCABULARY Birds evolved from theropod dinosaurs. airfoil A bird’s body is specialized for flight. Birds have spread to many ecological niches. air sac

Connect to Your World 7A analyze and evaluate You may share certain features with your parents or siblings. Perhaps your eyes are how evidence of common ancestry among groups is provided by the the same or your nose is the same shape. Certain traits make it easy to identify fossil record, biogeography, and homologies, including anatomical, your ancestors. Birds have a bit more trouble. That cardinal at your bird feeder would molecular, and developmental; probably be surprised to discover that it is related to a ferocious Velociraptor, but 7B analyze and evaluate scientific explanations concerning any data of birds are the surviving relatives of those prehistoric animals. Birds are dinosaurs that sudden appearance, stasis, and evolved powered flight. sequential nature of groups in the fossil record; 10A describe the interactions that occur among MAIN IDEA 7A, 7B systems that perform the functions of regulation, nutrient absorption, Birds evolved from theropod dinosaurs. reproduction, and defense from injury or illness in animals Most paleontologists agree that birds are the descendants of one group of theropod dinosaurs. Theropods were bipedal, or two-legged, dinosaurs that evolved during the Triassic period of the Mesozoic era. Most were carnivorous, and some, such as Allosaurus and Tyrannosaurus, were enormous. Theropod fossils support the hypothesis that these dinosaurs are closely related to birds. They show that birds and many theropods share anatomical features, including • hollow bones FIGURE 3.1 Fossil evidence of shows features • fused collarbones that form a V-shaped wishbone, or furcula such as feathers and a beaklike • rearranged muscles in the hips and legs that improve bipedal movement structure not seen in dinosaurs. • “hands” that have lost their fourth and fifth fingers Archaeopteryx is an important • feathers link between dinosaurs and modern-day birds. In the 1990s scientists discovered theropod fossils with feathers. This important discovery showed that feathers did not originate as an adaptation for flight. These theropods were covered with feathers, but they did not have wings. They were running animals. This means that feathers originally had another function in the theropods. They may have been insulation that trapped air to keep the animals warm. Or they may have been used in court- ship or territorial displays. As birds evolved, they used the feathers they had inherited from their theropod ancestors to form wings. The oldest undisputed fossil bird is shown in FIGURE 3.1. Archaeopteryx was a chicken-sized animal that lived about 150 million years ago. Like all modern birds, it had feathered wings and a furcula. But it also had many reptilian features, including clawed fingers, a long , and teeth. Because of its features, Archaeopteryx was classified as a . However, its feathers made it an important link between flightless dinosaurs and avian, or flying, dinosaurs, as well as the birds of today.

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©Dietmar Nill/Foto Natura/Minden Pictures A bird’s specialized body is for flight. Infer

bottom (concave). topthe (convex) up on and the curved include from theropod their ancestors. Othersare unique to birds. adaptations These for powered Some of flight. are them modifications of features inherited homologous to arms and covered by large feathers. ence that wing the up. lifts In birds, airfoil the is constructed of limbs that are difference above inair speed and below airfoil the produces apressure differ- airfoilthe than underneath it. The makes air move faster over top the of airfoil. An an is surface called kind of curved shapethe of an airplane wing. This to fly. Bird similar wingsto are curved Wings are structures that enable birds Wings Birds such owl as eagle the in groundthe is unknown, but future fossil discoveries may provide an answer. predators. feathered those used Whether also arms they to back down glide to featheredtheir arms up to run trees and escape gests that theropods small could have flapped bing to flapping and Some research flying. sug- dinosaursthese moved from running and grab- down prey. their Scientistsdo not still know how were bipedal carnivores that hunted by running “ground-up” the port hypothesis. Many theropods ship theropods between and birds tends to sup- featheredtheir arms for balance. birds evolved from running animals that used contrast, “ground-up” the hypothesis suggests that featherstheir to down glide to the floor. In suggests that birds evolved from animals that used of f • • • • • MAI

repr hol an ac str wing The f Scientists have two hypotheses for origin the light inbirds. The “trees-down” hypothesis How might hollow bones have helped theropods move more efficiently? N ong muscles flight that move wings the ID low bone structure that minimizes weight oductive adaptations s that produce flight tive metabolism that provides to muscles the energy ossil evidence showingossil evidence acloserelation- E A airfoil

is curved down on is curved

The curved shape The curved 7 a , 7 b , 10A FIGURE 3.2 3.2 FIGURE have many adaptations specialized VISUAL VOCAB VISUAL airfoil create lift. in airpressure above and below the concave onthebottom.Differences An airfoil isconvex onthetop and Chapter FIGURE 3.2 FIGURE quiet anddeadly predator. makingthisnocturnalbirdflight, a an e agle owl are adapted for silent


A Closer Lookat Amniotes

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Bird anatomy is highly adapted, with unique features that help to conserve energy and allow flight.

Feathers Feathers are complex branching structures made of keratin. Not only are feathers important for flight but they also provide insulation that helps maintain body tem- barb perature and protect the bird’s skin. Feathers can be shed and replaced if they are damaged. barbule





pectoral muscle small intestine

sternum (keel)

heart liver cloaca

Hollow BOnes The strut system found in the bone structure of birds reduces weight with- strut out compromising strength. Unlike other amniotes, birds have bones that are hollow and are directly connected to the bird’s .

CRITICAL A few species of birds do not actually fly. How might the unique features of VIEWING birds be beneficial for penguins, which spend most of their time in water?

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Muscles A bird’s chest muscles provide the power for flight. In almost all vertebrates, R E ADI N G TO OLB ox chest muscles attach to the arms and the breastbone, or sternum. But anyone who has carved a chicken knows that a bird’s chest muscles are enormous. TAKING NOTES Use a main idea diagram to take They are so large that the sternum has evolved a large keel, or ridge, that notes on how the features of supports the muscles. The keel provides a large attachment surface for the chest birds help them to achieve muscles, and serves as an anchor that they can pull against to flap the wings. flight. When birds fly, their chest muscles contract to pull their wings backward and down. The downstroke moves the wings to produce lift and propel the animal forward. Deeper chest muscles contract during the upstroke, moving adaptations for flight the wings forward and up until the bird starts another downstroke. Metabolism Flying takes a lot of energy. Birds are endotherms and have active CONNECT TO that can produce large amounts of ATP for the flight muscles. But maintaining Cellular Respiration an active metabolism during flight requires an enormous amount of oxygen. Birds require large amounts Birds meet this challenge with a respiratory system that increases the amount of ATP to provide the energy of oxygen they can take out of the air. needed for flight. Recall from Cells and Energy that cellular A bird’s body is filled with a series of air sacs air sac respiration needs oxygen and that connect to the lungs. Air sacs store air as the glucose to produce ATP. Air sacs trachea bird breathes. During flight, movements of the lungs provide a great deal of oxygen, furcula help push air through the air sacs and but birds must also consume air sac large amounts of food to lungs. Inhaled air travels through the lungs and support their active metabolism. air sacs in such a way that oxygen-rich air is always available. In other vertebrates, oxygen-rich air mixes with oxygen-poor air inside the lungs during respiration. But because only oxygen-rich air flows through a bird’s lungs, the amount of oxygen that can be absorbed into the bloodstream HMDScience.com

is dramatically increased and maximizes a bird’s go online metabolism. Respiration in Vertebrates Bone Structure The structure of a bird’s skeletal system is different than that of other amniotes. Birds have evolved bones that are hollow. As you can see in FIGURE 3.3, inside bird bones, a system of struts and support structures maintain the bird’s bones to meet the demanding requirements of flight. In all birds, many bones are ­connected to the air sacs, and air fills the cavities in the bone, aiding in flight. This adaptation further increases the amount of air in a bird’s body and makes flying easier. It also helps to decrease the mass of the bird. In fact, a bird’s skeleton makes up only five percent of its overall body mass. Reproductive Adaptations The reproductive organs of both male and female birds are only active for the two to three months of the season. During the rest of the , the unused organs shrink to reduce the mass of the bird. This weight-reducing adaptation serves to decrease the amount of energy needed for flight. Summarize How are bird bodies adapted to flying?

Chapter 26: A Closer Look at Amniotes 769 CorrectionKey=A DO NOT EDIT--Changes mustbemadethrough “File info” Unit 770 ShapeandDiet online go B A L K C I U Q 6. 5. 4. 3. 2. 1. An 4. Proc Probl Sk examine three different typesoffeathers. Feathers are features that allow birds to adapt to auniqueway oflife. Inthislab, you will FeathersComparing 2. 5. 3. 1.

8: Infer Apply Apply Infer Analyze Analyze Repeat st resistance you feel asyou move thefeather through theair. Hold andw theendofshaft some ofthebarbs ofavane. Jointhemagain withyour fingers. Observ breaking it. With your other hand,gently tryto bendtheupperthird ofthefeather without Examine thecentr the fe Obtain alarge quill andstudyitsoverall shape,structure andweight. Draw ill

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ture ofdown feathers helps to insulate abird? have wings that are at to small letfly them too all. wings adapted to “fly” inwater. Flightless birds, such as ostriches and emus, wings that help to them maneuver through tight spaces. Penguins have short of songbirds, including woodpeckers, finches, and robins, have stout, tapered wide, broad for wings at soaring specialized low over speeds land. Many types forized long soaring distances over water. Hawks, and eagles, condors have such as blue-footed the booby in wings that allow to them maneuver easily. very In contrast, some , The shape of abird’s way the wing reflects Most it . birds have short, broad WingShape in Differences to visible physical differences shapes inthe and of feet. wings, the beaks, have adapted to many kinds of habitats and of methods feeding. This has led more thanof 9000species bird today. we see Through natural birds selection, one group mass the that extinction. This group survived diversified into the went with dinosaurs. the extinct birds modern All are descendants the of the Birds first evolved during Mesozoic the era, but most Mesozoic bird species MAI i ng N ID t? E A

7 a , 7 b FIGURE 3.4, FIGURE have long, narrow wings special- • • • M

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(tl) ©Frans Lanting/Minden Pictures; (tr) ©Pete Oxford/Nature Picture Library; (cl) ©Arthur Morris/Corbis; (cr) ©Royalty-Free/Corbis; (bl) ©dkimages.com; (br) ©William Osborn/Nature Picture Library an Infer 26.3 3. 2. 1. Re FIGURE 3.4 FIGURE With few exceptions, bird feet have four But toes. as Foot in Shape Differences ripping and open fruits cracking nuts. out of water. the Parrots thick, their strong use for beaks pouches of skinattached for to beaks their scooping fish reach into deep flowers for nectar. Pelicans have large such as hummingbirds, have that long, can beaks thin out like insects chisels toofbeaks pry birds, trees. Other ofteninsects have pointed thin, bills. Woodpeckers have hooked to tearfrom flesh its prey. Birds that catch dives is into of eagle bald the The beak ocean. the itsuses long, to capture spearlike beak on fish bird’s the different functions. For example, blue-footed the booby Galapagosthe Islands, shapes are beak adapted for many many inthe observed of finchspecies is asheath ofbeak keratin that covers jaw the bones. As The shape of abird’s how reflects it eats. beak Abird’s Shape Beak in Differences backward, which letsperch them on horizontal tree limbs. have three pointing toes forward and one pointing Sparrows clingthem tree trunks. to vertical and crows pointing forward and two pointing backward, which lets and tree bark. Woodpeckers, for example, have two toes that live intrees have feet that can grab onto branches heavy that to use capture they prey. and kill Birds Predatorypaddles. birds have such eagle as bald the webbed feet, with skinconnecting to toes the form The blue-footed booby and other aquatic birds have d very long and narrow wings? narrow and long d very

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evolution? endotherm so for important bird from beinganectotherm to beingan closely related. Whyistheevolution pecker’s feeding habits? these features related to thewood- and astout, pointed beak.How are pecker hasanunusually long tongue Connect Analyze t ical

t The red-hea Reptiles andbir hi nk 7 i a n , 10 g ded wood- a ds are go online go Chapter 6. Se 3.4 FIGURE array ofwings, beaks, andfeet. selection hasled to a wide habitat andniche.Natural specifica

CO l caused these differences? What type of selection likely have dull brown feathers. re Male cardinals have bright blue-footed booby e green woodpecker d feathers, whereas females c NNE HMDScience.com Self-check Online

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Web BIOLOGY Beak Shape and Diet Internal Body Temperatures Sea Turtles The seven Examine how the shape of Compare body temperatures of four species of sea turtles on a bird’s beak allows it to different animals over a range of Earth are all endangered or take advantage of specific environmental temperatures to make threatened. Find out if we food sources. inferences about the animals. can help reverse their paths to extinction. (bl) ©John Mosesso/NBII; J. (br) Vision/Getty ©Digital Images

online biology 772 HMDScience.com CorrectionKey=A DO NOT EDIT--Changes mustbemadethrough “File info”

©Michael Durham/Minden Pictures mals that can fly. features. are the only mam- ha FIGURE 4.1 FIGURE eutherian gland mammary VOCABULARY injury orillness inanimals reproduction, anddefense from of regulation, nutrientabsorption, systems that perform thefunctions the interactions that occur among taxonomic groups...; 10A describe 8C compare characteristics of hierarchical classification system...; categorize organisms usinga differential reproductive success; 8B natural selection...result in evaluate how theelements of fossil record; 7Danalyze and sequential nature ofgroups inthe sudden appearance, stasis, and explanations concerning anydata of 7B analyze andevaluate scientific molecular, anddevelopmental; homologies, includinganatomical, fossil record, biogeography, and among groups isprovided by the how evidence ofcommon ancestry s all of the basic mammalian 7Aanalyze andevaluate 26.4

This Yuma myotis 7 8C, 10 a , 7 b a , 7D, 8B, Mammals characteristics. shareseveralAll mammals common su addition to hair, what other traits make mammals unique? fromhumans andother mammals apart reptiles, birds, amphibians, andfish.In Each timeyou get your haircut,you are having clippedoffafeature that sets Your to World Connect ke

characteristics. from reptilian these ancestors. Earth’s first mammals appeared more than 200 of characteristics the we now only see inmammals were inherited actually alive today. are They from descended agroup of carnivorous synapsids. Many All bat in feeding, and reproductivesocial, behaviors. Modern mammals—such as the y • • • • MAI cceed dinosaurs as a dominant terrestrial vertebrate. terrestrial dominant a as dinosaurs cceed MAI


mammals Mam a jaw t a mid mam hair Modern mammals are dividedint mammalsAll share several common characteristics. N n N FIGURE 4.1 FIGURE ID c ID ept mary glands mary mals are as ancient as dinosaurs and are only the group of synapsids dle ear containingdle three bones E hat letschew them food their E A terrestrial life form. niches. In time, mammals dinosaurs succeeded as a dominant went vacant their and mammals extinct, filled ecological survived mammals adistinctadvantage over reptiles. When dinosaurs the owntheir temperature body was an important adaptation that gave producedrich milk by adapted highly glands. The ability to regulate reproduced by laying and eggs, nursed young their on nutrient- AS e

are active, large-brained, endothermic animals with complex modern-day shrews. probably They lived underground, 7A, 10A 7D, 7B, volutionary adaptations allowed mammals to to mammals allowed adaptations volutionary —come inmany shapes, but share they of aset four anatomical andnoses short may legs. They have looked similar to eaters.niche insect as nocturnal hunting Triceratops, tiny rodentlike mammals had found a Tyrannosaurus Cretaceous while the During period, rex was becoming top the predators and herbivores on planet. the million years ago, when dinosaurs were already on their way to Fos

sil evidence suggests evidence sil that early mammals had long o three maingroups. Chapter 26:ACloser Lookat Amniotes

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mother for three to eightweeks. These piglets nurse will from their vide nutrientsto theiroffspring. milk inmammaryglands t FIGURE 4.2 FIGURE survive andreproduce. thus makingthemless likely to obstructions whencatching prey, causes resistance andmay be environment ofwhales, hair of individuals. Intheunderwater traits that increase thefitness that natural selection favors from Principles ofEvolution whales donot have hair. Recall are mammals, butmost adult accurately, hairfollicles. Whales mammalsAll have hairor, more Na Unit 8:Animals CO t ural NNE C

T Mammals produce Se

T O l e c t io o pro- n bones inreptiles we see today. impulsesnerve and interpreted by brain. the This is same the configuration of , which transmitted sound to inner the ear, where it was converted to together.fused The of reptiles these contained only one bone, the “goose bumps,” your insulating air layer is thickening to help keep you warm. mals get cold, muscles around the follicles pull the hair upright. When you get which insulates the animal, much like a down vest insulates you. When mam-

grows out of a follicle in the skin them retain heat. Each hair is a long, thin shaft of dead, keratinized cells that Mammals are furry. Most species are covered with a layer of hair that helps Hair FIGURE 4.3, 4.3, FIGURE ferred vibrations to inner the ear intetrapods. Asimilar illustrated shift, in . that Bones supported jaws the bones became infish that trans- are unique to mammals. were They derived from reptilian jaw bones. stapes, found is also inother tetrapods. The other two, and the incus, Mammals have bones three small middleear. intheir One of bones, the the Middle sensory bristles. sensory mammals that have lost most of hair, their such retain as whales, some mammals have long, whiskers information. stiff that sensory collect Even hedgehogs have hairs that modified form protective stiff quills. And many of pigmented hairs provide for many mammals. Porcupines and up knowsfluff that mammals can hair use for behavioral displays. Patterns Syn Hair a The t apsids such as the had jaws that were made of many bones op of part hyoid the arch to form modified stapes the became inearly lso haslso other functions. E occurred as mammalsoccurred evolved from reptilian their ancestors. ar nipples or teats that young mammals, such as piglets the in ofsurface skin.In the most mammals, ducts the empty into connected of to aseries ducts. The ducts bring to the milk glands contain masses of milk-producing tissues that are areas,specific such as udders inacow’s groin. Mammary glands along belly. the mammals Other have glands only in females. Some mammals, such as dogs, have of aseries present males and inboth females but produce only milk in develop. minerals, and that help young animals grow and produce contains Milk milk. water, sugars, protein, fats,

called milk. milk. called chance fluid Females of survival. aspecialized them feed mals, but provide care for after them to birth increase their Mammals have fewer offspring than other classes of ani- Glands Mammary FIGURE 4.2, 4.2, FIGURE Mam mary glands aremary unique to mammals. are They can hold mouth inthe and suckle. Mammary glands . The hair traps a layer of air next to the skin,

Anyone has who watched afrightened cat are specialized glands are that specialized

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Over time, the formation of these bones changed. Reptilian Ear Bone Two bones, the quadrate and the articular bones, eardrum once formed the joint between the jaws of reptiles. middle ear These bones evolved to serve a different function— hearing. In mammals, the quadrate and articular bones are now tiny and are incorporated into the middle ear as the malleus and the incus. Sounds collected in the ear canal vibrate the eardrum. These vibrations are transferred through the malleus and incus bones to the stapes. These tiny vibrations are converted into nerve impulses in the inner ear and stapes then interpreted by the brain. The ability to detect small vibrations allowed mammals to hear higher- Mammalian Ear Bones pitched sounds. eardrum inner ear malleus Mammals developed the ability to chew their food. incus Amphibians, reptiles, and birds usually bite off large chunks of food or swallow it whole. Most of their mechanical processing and nutrient absorption occurs inside their digestive tract. Mammals, in contrast, start to break up their food as soon as it enters the mouth. ear canal stapes A set of adaptations in the mammalian jaw makes chewing possible. While food is in the FIGURE 4.3 As mammals evolved, mouth, a secondary palate separates the nasal and oral cavities. It keeps the the structures of the inner ear passages for air and food separate, so mammals can chew and breathe at the changed. The incus and malleus same time. In addition, complex muscles can move the jaw from side to side. bones that were once part of rep- tilian jaw structures evolved in Infer Hair was an important adaptation for mammals. How might hair and other ways that enhanced hearing. adaptations have enabled mammals to survive where reptiles could not?

MAIN IDEA 7b, 8b, 8c, 10a Modern mammals are divided into three main groups. More than 4500 species of mammal are alive today. They can be classified into three groups: , , and eutherian mammals. Monotremes R E ADI N G TO OLB ox The monotremes are mammals that lay eggs. They are remnants of an ancient VOCABULARY group of mammals that have characteristics of both mammals and reptiles. The name monotreme comes The group split off from the line that led to the other living mammals some- from a Greek word that means “single opening,” referring to time during the Mesozoic. Their fossils suggest that they once lived through- the cloaca opening, which out the Southern Hemisphere. But today only three species of monotreme these mammals have in survive. The duck-billed is found only in and Tasmania. common with birds and Two types of echidna live in Australia, Tasmania, and New Guinea. reptiles. (t) ©John Cancalosi/Nature Picture Library; Heald/Nature (b) Picture ©Tony Library

Chapter 26: A Closer Look at Amniotes 775 CorrectionKey=A DO NOT EDIT--Changes mustbemadethrough “File info” 776

lakes insearch offood. scrape thebottomofrivers and The platypus uses to thisbill tightly packed withnerve endings. oftheduck bill FIGURE 4.4 FIGURE FIGURE 4.5 FIGURE until itismature. mammary gland, where stay itwill pouch, theinfant attaches to a the mother’s abdomen.Insidethe that develop withinapouchin Austra Unit 8:Animals lia gives to birth tinybabies

The red kangaroo of The shovel-like -billed platypus is their mother’stheir belly. But monotremes do not have nipples. Their babies from lick on milk pools glands. Whenmary monotreme babies hatch, mothers their milk. them feed Monotremes have also characteristic mammalian features, including mam- characteristics such as mammalian and reptilian features. Monotremes have retained reptilian After fertilization, developed live young that grow to maturity inside amarsupium, or pouch. babies, such as one the in seen marsupial give species only birth afew weeks after fertilization. The immature amountthe of embryo the develops time inside short. mother the Most is very a that exchanges nutrients and wastes with mother’s the systems. But of marsupial. Kangaroos, wombats, and koalas, are afew of 282living the species Marsupials mother’s pouch. marsupiumthe and nurse for up to six months before emerging from their gone over extinct most of former their range. Most living are species found • • •

amn reproductive tracts a sing a spra Monotremes such as platypus the in Fos sil evidence shows evidence sil marsupials once livedover all world. the have They iotic eggs with leathery shells thatiotic with leathery eggs develop outside body the le external opening, called the cloaca, for the le externalopening, called urinary, their digestive, and wling posture only inAustralia and New Guinea. Afew live inSouth America. Marsupials One species, the Virginia the One species, , lives inNorth America.

marsupial to develop embryos begin internally, attached to Australian marsupials have diversified into many forms, and there are many examples of convergent evolution flying squirrels.flying similar to unrelated mice, moles, anteaters, and anteating, and gliding marsupials that are physically For example, Australia is home to mouselike, molelike, animalseach the case, share roles. similar ecological marsupials these between and eutherian mammals. In are mammals that give to birth immature, under- FIGURE 4.5, 4.5, FIGURE FIGURE 4.4 4.4 FIGURE attach themselves to anipple inside have amix of ancestral

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©Terry Whittaker; Frank Lane Picture Agency/Corbis 26.4 of marsupial and eutherian mammal reproduction. reproduction. mammal eutherian and marsupial of Contrast and Compare 2. 1. Re FIGURE 4.6, 4.6, FIGURE mammals the All most familiar to you are eutherians. E development. In some including species, tiger in Bengal the months—and babies the are at born amore advanced stage of onlythe example of adisposable organ. tion and leaves mother’s the following body The birth. placenta is removes waste products. The placenta only forms during gesta- motherthe delivers oxygen and nutrients to embryo the and mother forms an organ placenta. the called Through placenta, the mother’s uterine The wall. connection the between and the In most eutherian development, an embryo is attached to the ing most because marsupials aplacenta use also during embryo development. mammals are commonly placental mammals, called but term this is mislead- give to birth live young that have completed development. fetal Eutherian are able to get up and within hours run of birth. isborn most vulnerable to predators, it so is important that they as or deer horses, shortly time the after new- is the when birth parental care on can until own. survive their they In others, such of primates, humans, the evolved ability the about to think ancestors. their from land-dwelling mammals. Bats evolved powered And flight. one group Three groups of aquatic eutherians—whales, manatees, and seals—evolved fast carnivores such as cheetahs and massive herbivores such as elephants. manatee, and horse appeared afterwards. soon Modern eutherians include million years ago, and first known the of species bat, elephant, appeared quickly. and carnivores appeared about 55 vacant niches, ecological and groups modern the of mammals

utherian Mammals utherian different from reptiles? mammals? among thethree livinggr How doesfetal development differ What features make vi Eut Aft ew er the extinctioner of the dinosaurs, the eutherians quickly filled herian gestation lasts longer than inmarsupials—often i Formative Assessment n newborns arenewborns relatively still helpless and extensive need g

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classified monotremes differently? features. How mightscientists have had both reptilian andmammalian ing to early scientists because they Classify diversity? reign helplead to today’s mammal e Summarize xtinction thatxtinction endedthereptile t ical 8 c

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CO the role of parental care? offspring produced and in mals differ in the number of themselves. How do mam- hatch they must fend for When the young turtles and return to the ocean. 20 A sea turtle may lay up to 0 eggs in a nest, then leave l tiger stay will withtheir NNE HMDScience.com Self-check Online 7 C

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the two terms ineach ofthefollowing pairs. Describe one similarity andonedifference between Compare andContrast

following questions. Use thedefinitionsofword to parts answer the the uniquecharacteristics ofamammal.” gland, you could mammarygland isoneof write, “The example, for theterms mammalandmammary vocabulary terms inthis chapter are connected. For Writ V R 26.1 vo Chapter 8. 6. 4. 2. 5. 9. ocabulary Connections 3. -par endo- pulmo- P 7. 1. eviewing art

endotherm, ect oviparous, vivipar pulmonary circuit, sy use intheword oviparous? How isthemeaning ofthesuffix marsupia ture regulation strategy ofmammals andbirds? Why istheprefix endo- reptil circuits. Explain whytheprefix endotherm, mammal e asentence ortwo to clearly explain how the

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of mammals? How doesdev of reptiles? How isthemammali do this? in apredator-free environment, whymightithave to 95 percent ofitstimeinunderground burrows. Even ecological nichethebird fills? What three par The desertt four-chambered heart. ofathree-chamberedfunctions heart andthose ofa Describe onesimilarit flight? How istherepr from theropod dinosaurs? What five piec Summarize therela reptiles, andmammals andtheirancientancestors. explain ofeach. thefunction Name thefour membranes f pos What isthesternum? How doesithelpmake flight croc Compare how snakes andlizards findprey withhow What are two ways that reptiles can reproduce? where reptiles cannot survive? pos Birds live inhot andinAntarctica. How isit sible for birds? sible for birds to live inhot andfrigidenvironments odiles findprey. HMDScience.com Interact 7 A

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Critical Thinking 23. Analyze A person goes out for a jog wearing a jacket Analyzing Data Choose a Graph because the morning is cool. After about 15 minutes, the The table below shows the weight loss of two box person feels very warm and has to take off the jacket, turtles during . A should lose only even though the temperature hasn’t changed. Explain about 1 percent of its body weight during each month 10a what is happening. of hibernation and no more than 5 percent during the 24. Classify Imagine that a new animal has been discovered entire hibernating period. Use the data to answer the in the rain forest. It has four limbs and a tail. Scientists next two questions. observe that it can swallow prey larger than its head. It gives birth to live young. Based on this information, how Weight Loss During Hibernation would you classify this animal? Explain your answer. Turtle Nov Dec Jan Feb Mar 8b No. 1 600g 594g 588g 582g 576g 25. Explain Why does the number of native reptile species No. 2 600g 590g 585g 580g 576g decrease as you move away from Earth’s equator?

26. Analyze Feathers are one of the most important adaptations for birds. Why are feathers a more useful 32. Graph Which type of graph would best represent both adaptation for flying than hair? sets of data in the table? Why?

27. Infer Elephants and leopards both live in Africa, where it 33. Evaluate Based on the differences in mass over the is hot. But elephants have very little hair, and leopards course of hibernation, which turtle will be healthier at have a full coat of hair. Explain why this might be. the end of hibernation? Explain your reasoning. 8c

28. Analyze Though it is bad manners, why is it possible for Making Connections a person to talk while chewing a mouthful of food? 34. Write a Script Birds, reptiles, and mammals coexist in Interpreting Visuals many environments on Earth. But many times their paths cross and confrontations occur. Perhaps while a is Use the following illustration to answer the next three feeding, a vulture may fly down to try and get a bite to questions. eat, or maybe a bird’s nest is being invaded by a reptile. from lungs to body Choose a place where two very different amniotes might interact, and write a script of an imagined conver- to body 1 sation between them. Using what you have learned about birds, reptiles, and mammals and how they function, have them discuss advantages and disadvan- tages of each other’s lifestyles and how their conflict could be resolved. 8c 2 35. Distinguish Look again at the picture of the tarsier on to lungs the chapter opener and read the description. Despite body parts that might remind you of other types of animals, why are scientists sure that the tarsier is a mammal? 3

29. Describe Blood coming from the lungs enters which part of the heart? Give the number from the diagram above and identify the part. 30. Analyze Blood going to the body comes from which part of the heart? Give the number, and name the part. 31. Explain Is this a three-chambered heart or a four-cham- bered heart? Explain how you know.

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Biology End-of-Course Exam Practice

Record your answers on a separate piece of paper. A The genes in arctic fox populations are MULTIPLE CHOICE unstable. B Reddish brown fur during the fall is likely not 2E selected for in arctic fox populations. 1 A researcher studies dairy cows to determine if C White fur during the winter is a trait that was feed type affects milk production. The researcher selected for in arctic fox populations. gives each cow one of the three types of feed for a D The that controls fur color is not month and measures milk production. Which of affected by temperature. the following sources of error was unavoidable in this experiment? 8B A the genetic makeup of cows in each group 4 Amniotes are multicellular animals whose B the average age of cows in each group embryos develop in an enclosed membrane. C the number of cows in each group What else must be true of all amniotes? D the types of cows in each group A They can only reproduce asexually. B Fertilization is always external. 2G, 7B C They lay eggs during their life cycle. 2 D Half of their DNA comes from each parent. Fossils Discovered at Hypothetical Site THINK THROUGH THE QUESTION 1000 B D First, think about what an embryo is. Can an embryo 750 be produced asexually? Next, eliminate answer choices that could be true for some amniotes, but 500 A may not be true for all amniotes.

250 Fossils discovered Fossils C 0 2G, 7A 500 250 1 5 Millions of years ago The graph above shows the number of fossils found at a hypothetical site from each time period over the past 500 million years. Which of the following is best supported by the data? A Many speciation events occurred at Node A. B Nodes B and D indicate a lack of . C Species diversity increased after Node D. D A possible mass extinction occurred at Node C. The illustrations above show the bones of the forelimbs of three organisms. The similarities in 7E, 9C, 11B bone arrangement support the hypothesis that 3 During the summer, the arctic fox produces these organisms — enzymes that cause its fur to become reddish brown. These enzymes do not function during A are members of one species the winter, causing the fox’s fur to become white B descended from a common ancestor and blend in with the snow. Which of the C have adaptations for similar environments following statements is most likely true? D have the same genetic information

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