Fossils (Science Matters)

7/29/2019 Fossils (Science Matters)

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Studying FossilsFossils are the rocklike remains of ancient animals andplants. A fossil can be a hard part of an animal, such asa shell or a tooth. It can also be a footprint left behindin the mud. Fossils are usually found in layered rockcalled sedimentary rock.The word fossil comes from the Latin word fossilis,which means "dug up."

A dragon fly th at is preserved as a fossil looks exactly th esame as a living drag onfly.


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Fossil FactsFossils teach scientists ab out th e past. They he lpscientists understand what Earth was like beforehumans lived.

Skull fossils help scientists learn how dinosaursheard, saw, sm elled, and t h o u g h t. F oo tprint fossilstell scientists how fast dinosaurs ran.

A person who studies fossils for a living is calleda paleonto logis t .

Paleontologists study fossil ized dung calledcoprol i tes.This helps them understand whatdinosaurs ate.

Many of the dinosaurs in museums are not reallyfossils.They are copies of the original fossils, madefrom l ightweight mater ials.


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Gone ForeverMillions of plant and animal species have livedon Earth during the past 3 billion years. Manyof these species, such as dinosaurs, are now extinct.Paleontologists study fossils to learn about creaturesand plants that lived in the past. Fossils tell when andhow these plants and animals lived. However, fossilshave not been found for many species. Scientists maynever find fossils for some species.

Fossils of the A lbertosaurus, such as the one above ,are rare.This dinosaur lived 74 to 76 million years ago.


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A Fossil is BornMost animals and plants dono t become ;fossils. Manyof the m ro^h jOthers dry upand blow awayin th e wind.! H iSome are eatenby scavengers.A fossil form s r! ' J " i r ' 1 1 I 1w hen a p lant or the body of a dead animal is coveredby m ud . Over t ime , sediment covers the body or plant.A fter th ou san ds of years, it becom es a fossil. Only a fewplants and animals become fossils. Still, fossi ls continueto form every day. Future scientists wil l f ind the fossilstha t form ed today. ! - || ' I Scientists have fo u nd many sea creature fossils.This isbecause sed ime nt is usually de po sited , or laid do w n ,in th e ocea n. ,, :! i


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How Fossils FormFossils can form in many ways. The remains of a plantor animal may be replaced by minerals. They maybe dissolved over time so that only an impressionrem ains. They may change to a different form.Many fossils become stone. This happens when saltwater enters a plant or animal's remains. Over time,the water evaporates and the remains crystallize, orharden. The plant or animal remains appear to haveturned to stone. Petrified Forest National Park inArizona has many trees that have become stone.

Arizona's Pe trified Forest National Park conta ins fossilsthat are 225 million years old.


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Insects in AmberNot all plants and animals become stone fossils.Sometimes a whole plant or animal is preserved.Then scientists see exactly what the plant or animallooked like when it was alive. Mill ions of years ago,sticky sap oozed fro m pine tree stems. Som etim esan insect or plant seed became stuck in the sap.Over t im e, the saphardened and becameanother type of fossi l ,called amber.Amber is yel low andlooks like glass.Today,people make jewelryou t of amber. Am berpieces with fossils ofinsects or seeds insidethe m are valuable. Most amber is mined.Lumps weighing up to18 pounds (8 kilograms)have been discovered.


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Dinosaur FootprintsFootprints left in mud are called trace fossils. Thesefossils tell scientists how fast an animal moved. Tracefossils tell the animal's height and weight, too. Verylarge animal footprints are spaced far apart. Smallanimal footprints are close together. If many animalfootprints are found together, scientists know that theanimals lived together in herds.The smallest dinosaur footprint found was only 1 inch(2.54 centimeters) long. The footprint was likely madeby an animal about the size of a sparrow.

Trace fossils are more c om m on tha n fossils of an entirebody. One animal can leave thousands of traces behind.


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Make Your Own FootprintHave you ever thought about making your ownfootprint? Try the experiment below to createyour very own trace fossil.

First, fi n d a piece o f clay. Place the clay on a piece ofcardb oard.T hen , sm ooth and f lat ten the c lay using aroll ing pin.The clay should be about 2 inches (5.1 cm)thick. Take off your shoe and sock. Press your bare footinto the c lay to make a fo ot pr in t. ' H ' INow set the clay aside to harden.A fter a few days, th e clay w ill ; j j i | 'be as hard as stone. One |day it w il l be a fossil.


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Fossils Over TimeScientists have divided Earth's historyInto blocks of time called eras. Differenttypes of animals lived during eachera. Fossils form in layers in the rock.Scientists can te ll which eras animalslived in from the layer of rock thatcontains the fossils. Fossils found inupper layers are younger than fossilsfound in lower layers.

Precambrian Era4.6 billion to 545million years agoDuring this time,simple life forms,such as algae,appeared inEarth's oceans.

4.6 billion years ago

Precambrian Era


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Paleozoic Era545 mil l ion to 250 mil l ionyears agoDuring this era, insects,fish,land plants, and the firstreptiles appeared on Earth.

Mesozoic Era250 million to 65 millionyears agoDuring this era, dinosaurs andbirds appeared.Th is era is alsoknow n as the "Age o f Reptiles."

Cenozolc Era65 million years ago to presentAll types of mammals, includinghumans, appeared during thisera.The Cenozoic Era is alsocalled the "Age of Mam mals."

I 545 million L 250 million . 65 millionyears ago | years ago I years agotoday

Paleozoic Era Mezozoic Era' Cenozoic Era


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Dinosaur DetectivesPaleontologists study fossils to understand the typesof life that were on Earth millions of years ago. Somepaleontologists search for fossils. Fossils are also foundby other people. Some people see part of a fossilsticking out of the ground.Once a fossil is discovered, it is a paleontologist's jobto remove the fossil from the ground. The fossil is sentto a laboratory to be studied.

Paleontologists often w ork o utdoors, dig gin g for fossils.


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Digging Up the PastDigging up a fossil is difficult. Paleontologists mustbe careful not to dam age the fossil.

First, pa leon tolog ists use small too ls to clear awaythe material around the fossil.Then someone takespho tographs and draws p ictures o f the site. Paleontologistsstudy these images later.if a fossil is surroundedby soft material, suchas clay, it is wrap pe d inlayers of cloth dippe din plaster. When theplaster sets, the fossilis tu rne d over.Then theoth er side is plastered.Each fossil is labeled,so the scientists inthe laboratory knowwha t it is and w hereit was fou nd .


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Piecing thePuzzle TogetherOnce the fossilized pieces of an animal or plant areat the laboratory, paleontologists remove the plasterjackets. They use power tools to carefully removerock from each fossil. Once all the rock is removed,the fossilized pieces are glued together.Complete fossilized skeletons may be displayedin the museum. The pieces are very heavy, so acopy is often made using molds of the originalbones . A steel framework is bu ilt, and the bonesare connected together.

Fossils of com ple te ske letons are rare and valuab le.Paleontologists can learn more from com plete skeletons.


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What Did DinosaursLook Like?Paleontologists know w ha t the skin of somedinosaurs looked like.This is because they havefound fossilized impressions of their skin.

Paleontologists have no way of knowing the dinosaur'sskin color. However, some scientists believe dinosaurshad good eyesight.This may mean their skin wasbr ig ht ly colored so other d inosaurs could see th em . i!il,:i I U I I : I L : I :ii| ;ii \\ \ i i H , |i i : ;| Meat-eatmg dinosaurs may have had spots or str ipeslike a leopard or a tiger. Plant-eating dinosaurs mayhave been camouflaged to hide from predators suchas Tyrannosaurus .rex. Sc ientists may never knowexactly how , .d inosaurs looked.


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.. f - .The Great Bone RushThe first dinosa ur b ones were found in the 1820s. Atfirst, people did not know what they had found. Soon,they realized that reptile-like creatures must have oncelived on Earth. In 1842, British scientist Sir RichardOwen called these creatures Dinausauria, which means"terrible lizards."In the 1870s, the "Bone W ars" began in the Un itedStates. Two men, Othniel Charles Marsh and EdwardDrinker Cope, competed to find fossils. To get thefossils to museums quickly, the two men covered thefossils in plaster. This technique is still used today.

Sir Richard Owenwas a surgeon. Hestudied anatomy,fossils, and dinosaurs.


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A Life of ScienceBarnum Brown

Barnum Brown was one of the greatest fossil huntersof the twe nt ie th century. He was a pa leon tologist for66 years. Brown traveled all over the w or ld co l lectingdinosaur and nnammal fossils. He was the first personto discover the bones of a f ierce m ea t-eating dinosaur.Later, he called th e dinosa ur Tyronnosaurus rex.


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Surfing OurEarthHow can I find m ore inform ation

about fossils? Libraries have many interestingbooks abou t fossils. Natural history museums are greatplaces to learn abou t fossils.The Internet offers some greatWeb sites dedicated to fossils.

Where can I find a good referenceWeb site to learn more about fossils?Encarta Homepagewww.encarta.com

Type any fossil-related te rm into the search eng ine.Some terms to try include "dinosaur" and "paleo ntology."How can I find out m ore abo ut fossils, dinosaurs,and paleontology?Strange Sciencewww.strangescience.net

This Web site offers in form atio n ab ou t dinosaurs, fossils,and pa leon tology. It includes a tim e line, references forfurther research, and a collection of famous mistakes.


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Science in ActionLooking for FossilsAsk an adu lt to take you on a hike so you can look for fossils. Ago od place to look is along th e edges of cliffs.Take a m agnifyingglass so you can look closely a t the rock layers. Make notes abou twhat you f ind. If you find som ething interesting, leave it beh indfor others to discover.M ake Your Ow n FossilIt takes m illions of years to make a fossil. Youcan begin the fossil process at home.Fill a plastic container w ith dirt . Add somewa ter to the d irt. Stir the m ixture un til it is thickNow fin d an object, such as a shell or stick, andpush it into the mud until it is completelycovered. Set the m ixture aside fora few days un til it hardens. Nowbury the hardened mixtureoutside. It wil l take a long time,but one day, this may be a fossil.


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at Have You Learned?Are the dinosaursin museums realfossils or copies? In whichera diddinosaurs

live?

Can tree sapform fossils? What canturn intoa fossil?


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# When were[ \ fossils firstdiscovered?In wh at k ind ofrocks are fossilsoften found?

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W hich famouspaleontologistdiscovered\

What doesfossil meanin Latin?

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Wordsalgae: simple l iv ing things made upof one or more cells; the basic

units of l iving mattercamouflaged: colored sothat animals blend intotheir surroundingsdung: animal droppings or manureextinct: no longer alive anywhereon Earthinfipression: mark left behind afterpressure is applied to an objec tmammals: warm-blooded animalstha t nurse their yo un g

minerals: solid materials found inthe natural environmentpredators: animals tha t kil l and eatother animalspreserved: something that has notchanged over t imescavengers: animals that eatdead animalssediment: ma terial from rockscarried by water, wind , or ice,and left somewhere elsespecies: a group of similar animals

Albertosaurus 6amber 9bone 16,18,19Bone Wars 18Brown, Barnum 19coprolites 5dinosaurs 5,6,10,13,

14,17,18,19,20

Earth 5,6,12,13,14,18,20eras 12,13footpr in t 4 ,5 ,10,11insects 9,13museum 5,16,18,20

paleontologists 5,6,14,15,16,17,19Petrified Forest 8p lants 4 ,6 ,7 ,8 ,9 ,13,17rock 4,12,16,21Tyrannosaurus rex17,19


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Wordsalgae: simple l iv ing things made upof one or more cells; the basic

units of l iving mattercamouflaged: colored sothat animals blend intotheir surroundingsdung: animal droppings or manureextinct: no longer alive anywhereon Earthinfipression: mark left behind afterpressure is applied to an objec tmammals: warm-blooded animalstha t nurse their yo un g

minerals: solid materials found inthe natural environmentpredators: animals tha t kil l and eatother animalspreserved: something that has notchanged over t imescavengers: animals that eatdead animalssediment: ma terial from rockscarried by water, wind , or ice,and left somewhere elsespecies: a group of similar animals

Albertosaurus 6amber 9bone 16,18,19Bone Wars 18Brown, Barnum 19coprolites 5dinosaurs 5,6,10,13,

14,17,18,19,20

Earth 5,6,12,13,14,18,20eras 12,13footpr in t 4 ,5 ,10,11insects 9,13museum 5,16,18,20

paleontologists 5,6,14,15,16,17,19Petrified Forest 8p lants 4 ,6 ,7 ,8 ,9 ,13,17rock 4,12,16,21Tyrannosaurus rex17,19

Fossils (Science Matters)

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