原版英语RAZ 教案Early Birds - Fossils and Feathers.pdf

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1、www.readinga-WritingCreate a Venn diagram that compares a dinosaur and a bird fossil from the book.Write a paragraph explaining how they are alike and why scientists think birds may be related to dinosaurs.ScienceCreate a diagram that demonstrates the way two types of fossils are formed:fossils of a

2、nimal skeletons and fossils of traces left behind by animals.ConnectionsVisit www.readinga- for thousands of books and materials.LEVELED BOOK YWritten by Alfred J.SmuskiewiczEarly Birds:Fossils and FeathersA Reading AZ Leveled Y Leveled BookWord Count:1,240Early Birds:Fossils and FeathersEarly Birds

3、:Fossils and FeathersWords to Knowadaptcarnivorousdecompositiondescendedimpressionsmeteoritepaleontologistsrudimentaryspecieswww.readinga-What can we learn from fossils?Focus QuestionWritten by Alfred J.SmuskiewiczCorrelationLEVEL YT4040Fountas&PinnellReading RecoveryDRAEarly Birds:Fossils and Feath

4、ersLevel Y Leveled Book Learning AZWritten by Alfred J.SmuskiewiczAll rights reserved.www.readinga-Photo Credits:Front cover,page 9:Charles R.Knight/National Geographic Images;title page,pages 3,10,14,15(background):Jupiterimages Corporation;pages 4,8:ArtToday;page 5:Jim Zuckerman/Corbis;page 7:cour

5、tesy of National Park Service;page 11:Louie Psihoyos/Corbis;page 12:Ken Lucas/Visuals Unlimited;page 13(main):Renee Jean/Daily Journal/AP Images;page 13(inset):Mick Ellison;page 15(from top to bottom):iS Losevsky;page 15(2):iS Benet;page 15(3,4,6):iS;page 15(5):iS AxyutinaEarly Birds:Fossils and Fea

6、thers34Table of ContentsIntroduction .4Information from Fossils .5Prehistoric Birds .8Birds from Dinosaurs?.11Conclusion .14Glossary .16Index .16IntroductionMost of the species of animals that have ever lived on Earth suffer extinction.When the conditions of the environment change,such as when the c

7、limate cools or the quantity of food decreases,a species may die out if it cannot adapt to the new conditions.Paleontologists have learned about a wide variety of such extinct organisms from fossilsevidence of prehistoric life preserved in rock or other material.Some fossils are simple marks that an

8、 animal produced while moving,such as footprints or trails left in the ground.Others are hollowed-out impressions of an animals entire body made in rock.Still others are preserved remains of an animals body,such as bones or shells.Fossils show how new kinds of species developed over eons.For example

9、,scientists have discovered fossils that lead them to believe that birds developed from reptiles more than 150 million years ago;those reptiles may have been dinosaurs.These fossilized remains of a prehistoric bird contain many secrets of the past.A fossil of the flightless bird DiatrymaEarly Birds:

10、Fossils and Feathers Level Y56Information from FossilsWhen the vast majority of animals die,the decomposition activities of bacteria and fungi cause their bodies to gradually break down and disappear.However,if conditions are suitable,a dead animal may transform into a fossil,leaving behind clues ab

11、out its physical characteristics and how it lived.Typically,an animal that becomes immortalized as a fossil is buried in sedimentsuch as mud or sandimmediately after it dies.This is more likely to happen in or near rivers,the sea,or other bodies of water.Water that carries minerals,such as calcium,t

12、hen soaks into microscopic spaces inside the bones of the body.As more and more of the bone tissue dissolves and decays away,increasing amounts of minerals take the place of the bone.In time,a rocky duplicate of the animals skeleton is left.When the body decays completely away,impressions of an anim

13、als body formshowing such features as feathers or scales.All that then remains is the hollow space where the animals body was,surrounded by sediment.John Day Fossil Beds in Oregon is typical of places fossils are found.Soon after death,the water rises.The animals skin and other soft tissues decay aw

14、ay.The bone decays away.123An animal dies near a body of water.4The skeleton is buried by sediment carried by the water.Minerals replace the bone.5Early Birds:Fossils and Feathers Level Y78The bones and other characteristics of a fossil tell scientists what the animal looked like.These features also

15、 enable scientists to compare the animal with species living today.Similarities and differences between the features in the fossil and those of living organisms may reveal how the extinct creature behaved.For example,if the bones in the fossil are similar to bones in bird wings today,maybe the anima

16、l was capable of sustained flight.Such traits may also indicate that modern birds are related to this extinct animal.Paleontologists use different procedures to determine how old a fossil isthat is,to learn when the animal captured as a fossil lived.Because sediment accumulates year after year,fossi

17、ls found in deeper sediment are older than fossils in sediment closer to Earths surface.Scientists obtain their best estimates of a fossils age by analyzing certain chemicals in the rock that contains the fossil.Prehistoric BirdsPaleontologists have unearthed numerous fossils of extinct prehistoric

18、birds.The earliest known bird fossils are of a primitive reptile-like bird called Archaeopteryx(AHR-kee-OP-tuhr-ihks),which lived approximately 150 million years ago.These fossils offer compelling evidence that birds descended from reptiles.How Old Is That Fossil?The main chemical technique that pal

19、eontologists use to estimate the age of fossils is called radioisotope dating.This method is based on the fact that chemicals called radioactive isotopes break down to form other chemicals at a known rate over time.By comparing the amount of radioactive isotopes left in a fossil with the amount of t

20、heir breakdown products,scientists can calculate how long this decay process has been going on.That calculation,in turn,tells scientists how long ago the fossil formed.Paleontologists discover fossils,study the fossils,and sometimes help display the fossils in museums.Fossils of Archaeopteryx,such a

21、s this one,are among the most important fossils ever discovered.Early Birds:Fossils and Feathers Level Y910The fossils of Archaeopteryx show that this crow-sized animal had some characteristics resembling birds and others resembling reptiles.Like modern birds,Archaeopteryx had feathers,wings,and a“w

22、ishbone”(a forked bone in the upper chest).However,like a reptile,it had teeth and a long,bony tail.It also had three“fingers”with claws on each wing.Archaeopteryx probably flew rather poorly.Scientists base that conclusion on the structure of the animals sternum(breastbone)seen in fossils.The stern

23、um of Archaeopteryx was flat.Modern birds have a sternum with a protruding part where robust muscles used in flight are attached.Without such a sternum,Archaeopteryx would have lacked powerful flight muscles.Paleontologists have discovered several fossils younger than those of Archaeopteryx that dep

24、ict other birds.These fossils reveal how birds developed progressively modern traits over time.Hesperornis(hes-pur-OR-niss)and Ichthyornis(ik-thee-OR-niss)were two kinds of aquatic birds that lived approximately 90 million years ago.Fossils of Hesperornis show that this bird looked like a large loon

25、,with big webbed feet to assist it in swimming.It also had a beak lined with tiny teeth to enable it to catch fish.However,Hesperornis had only rudimentary wing bones,so it could not fly.Ichthyornis resembled a gull,with elongated pointed wings.It was probably an excellent flyer that dived into the

26、sea to capture fish.Fossils prove that many of the main types of birds we know today had developed by about 35 million years ago.These included birds that bore resemblance to modern chickens,doves,ducks,parrots,penguins,owls,and songbirds.Archaeopteryx(top)and pterosaurs(left)were some of the first

27、flyers besides insects.A fossil of Hesperornis shows it probably could not fly.Early Birds:Fossils and Feathers Level Y1112Birds from Dinosaurs?Paleontologists theorize that fossils depicting birds with reptile-like characteristics are signs that birds developed from reptiles.Scientists have also un

28、covered fossils of dinosaurs that possessed feathers and other bird-like traits.These fossils provide evidence that dinosaurs were the reptiles from which birds developed.Fossils indicate that carnivorous dinosaurs called coelurosaurs(sil-YUR-uh-sorz)were like birds in many waysthough scientists cla

29、ssify them as true dinosaurs.The fossils of the most birdlike members of the coelurosaur group are approximately 155 million to 135 million years old.They show that these animals were small for dinosaurs,most ranging in length from 2 to 10 feet(0.63 meters).They ran rapidly on two long,slender hind

30、legs,which each had four,clawed toes.Their bones were hollow and lightweight.They had sizable eyes.Some even had feathers.All of these traits are similar to those of birds.Since fossils exhibit these attributes,its logical to conclude that coelurosaurs developed into birds.One of the coelurosaurs th

31、at paleontologists understand best from fossils is Compsognathus(komp-SOG-nuh-thus).It is known from two well-preserved fossils,about 145 million years old,which were discovered in Europe.Compsognathus was one of the smallest dinosaurs that ever livedsome of these creatures were only the size of a c

32、hicken.Compsognathus had a long,thin neck and tail and long hind legs.On each of its short front legs,it had only two clawsan unusual feature for a dinosaur.Like other coelurosaurs,Compsognathus hunted by running after insects,lizards,and other diminutive animals and grabbing them with its razor-sha

33、rp claws and teeth.The features seen in Compsognathus and other coelurosaur fossils bear several similarities to the skeletons of modern birds.coelophysisEarly Birds:Fossils and Feathers Level Y1314Scientists know what this dinosaur ate because one of the fossils of Compsognathus includes the remain

34、s of its last meal in its stomach.The type of lizard seen in the stomach had extremely long legs,so this lizard must have been a fast runner.Thus,Compsognathus had to be quick to capture this prey.ConclusionMuch has been learned about prehistoric animal life from fossils.Some of the most fascinating

35、 fossils ever uncovered prove that,ages ago,there were creatures that had some characteristics of birds and other characteristics of reptiles.Fossils of these organisms lead scientists to theorize that birds developed from dinosaurs.Dinosaurs roamed the Earth for more than 150 million years,but they

36、 were unable to adapt when environmental conditions changed about 65 million years ago.According to scientists,Earths climate may have changed dramatically around that time,perhaps as the result of a meteorite impact.Although dinosaurs did not survive this change,birds did.Today,there are more than

37、9,700 species of birds thriving from the frigid Arctic and Antarctic to the torrid tropics.Some scientists actually classify birds as living dinosaurs.So the next time you see a songbird singing outside your window,might you really be watching and listening to a dinosaur?Compsognathus was a small di

38、nosaur that was similar to a fast-running,insect-catching bird.Fossil Bird in Its EggA 121-million-year-old fossil provides evidence that some prehistoric birdsunlike most birds todaycould feed themselves immediately after hatching from their eggs.The fossil shows the outline of an egg with a baby b

39、ird still curled up inside.The unhatched bird had a complete set of feathers,strong-looking bones,and a large skull.Most birds today are weak and naked when they hatch and must be fed by their parents.Early Birds:Fossils and Feathers Level Y1516Glossaryadapt(v.)to change to fit a new or specific sit

40、uation or environment(p.4)carnivorous(adj.)meat-eating(p.11)decomposition(n.)the process of decaying and rotting(p.5)descended(v.)related to and developed from another species(p.8)impressions(n.)marks or prints that are made when something is pressed on or into surfaces(p.4)meteorite(n.)a piece of r

41、ock or metal that has landed on a planets surface from outer space(p.14)paleontologists(n.)people who study plant and animal fossils(p.4)rudimentary(adj.)having an incomplete or undeveloped form(p.10)species(n.)a group of living things that are physically similar and can reproduce(p.4)IndexArchaeopt

42、eryx,810coelurosaurs,11,12Compsognathus,12,13Hesperornis,10Ichthyornis,10radioisotope dating,8sternum,9wings,7,9,10wishbone,9Cenozoic Quaternary Humans(65present)(2present)Tertiary Horses,apes (652)Mesozoic Cretaceous Flowering plants(24865)(14565)Jurassic Birds,mammals (213145)Triassic Dinosaurs (2

43、48213)Paleozoic Permian Seed plants(543248)(286248)Carboniferous Reptiles,giant insects (360286)Devonian Sharks,amphibians (410360)Silurian Mosses,coral reefs (440410)Ordovician Squid-like nautiloids (505440)Cambrian Trilobites,mollusks,jawless fish (543505)Precambrian time Bacteria,worms,jellyfish (4.5 billion to 543 million)Scientists divide Earths history into different eras and periods of time.During which era and period did birds first appear?*in millions of yearsEra*Period*Life That Appeared Early Birds:Fossils and Feathers Level Y