>> HUMAN HAVEN'T ALWAYS BEEN THE EARTH'S TOP DOGS.

ONCE DINOSAURS RULED THE WORLD.

LEARN MORE ABOUT THEM.

STAY TUNED.

"D4K" IS NEXT.

>> HELLO, I'M JOAN CARTAN-HANSEN.

THANK YOU FOR JOINING US HERE ON IDAHO PUBLIC TELEVISION AND ON THE WORLDWIDE WEB.

THE WORLD WAS A MUCH DIFFERENT PLACE WHEN DINOSAURS ROOMED THE EARTH.

DINOSAURS DOMINATED THE LANDSCAPE FOR MORE THAN 160 MILLION YEARS.

LONG BEFORE HUMANS WERE AROUND.

THE FIRST DINOSAURS LIVED ABOUT 230 MILLION YEARS AGO IN WHAT'S KNOWN AS THE TRIASSIC PERIOD.

OTHERS CAME AND WENT OVER THE CENTURIES, FINALLY DYING OUT ABOUT 65 MILLION YEARS AGO AT THE END OF THE CRETACEOUS PERIOD.

WE KNOW ABOUT DINOSAURS WE'VE LEARNED FROM THEIR BONES AND OTHER FOSSILS.

SCIENTISTS CALLED PALEONTOLOGISTS FIND, PREPARING, AND CAREFULLY STUDY EACH NEW SPECIMEN.

AND WHAT HAVE THEY FOUND OUT?

DINOSAURS STARTED AS SMALL MEAT-EATING ANIMALS.

THEY EVOLVED INTO THOUSANDS OF DIFFERENT TYPES, INCLUDING SOME OF THE LARGEST ANIMALS TO EVER WALK THE EARTH.

DINOSAURS WERE MEAT EATERS AND PLANT EATERS.

SOME HUNTED THEIR PREY.

OTHERS WERE SCARF JERS.

ONE WAY SCIENTISTS CAN TELL WHAT KIND OF FOOD A DINOSAUR ATE IS BY LOOK AT THEIR TEETH.

THE TYRANNOSAUR, OR T-REX, HAD HUGE TEETH, BUT IT WAS PROBABLY A SCAVENGER RATHER THAN A HUNTER.

DINOSAURS WERE NOT WARM-BLOODED OR COLD-BLOODED.

RATHER, SCIENTISTS THINK THEY WERE DINOSAUR-BLOODED, A CONDITION SORT OF LIKE BEING WARM-BLOODED BUT NOT EXACTLY.

THEY LAID EGGS LIKE BIRDS AND WERE GOOD MOTHERS, WATCHING OUR THEIR NESTS.

SOME RAN VERY FAST, AND THERE WERE AVIAN DINOSAURTHAT FLEW.

SO WHY DID SIGN SAUERS DISAPPEARING?

ONE THEORY IS THAT AN STEROID HIT THE EARTH IN THE YUCATAN PENINSULA IN MEXICO.

THE RESULTING EXPLOSION DESTROYED FORESTS THROUGHOUT MOST OF NORTH AMERICA AND MUCH OF SOUTH AMERICA.

IT WOULD HAVE CAUSED AN EARTHQUAKE, AND EVIDENCE OF A GIANT TSUNAMI HAVE BEEN FOUND AS FAR AWAY AS SPAIN AND BRAZIL.

THOSE DINOSAURS THAT SURVIVED THE IMPACT MAY WELL HAVE DIED BECAUSE THEIR FLOOD SUPPLY WAS DESTROYED.

BUT NOT EVERY DINOSAUR WAS WIPED OUT.

SCIENTISTS THINK THAT ONE SUBGROUP OF THE THEROPOD DINOSAURS EVOLVED INTO BIRDS.

PALEONTOLOGISTS CONTINUE TO FIND AND STUDY DINOSAUR BONES AND OTHER FOSSILS.

THEY'RE LEARNING NEW THINGS ALL THE TIME.

TAKING US BACK TO THE AGE WHEN DINOSAURS RULED THE EARTH.

AND JOINING ME NOW IN OUR POCATELLO STUDIO TO ANSWER YOUR QUESTIONS ABOUT DINOSAURS IS DAVID VARRICCHIO, ASSISTANT PROFESSOR OF PALEONTOLOGIST AT THE EARTH SCIENCES DEPARTMENT AT MONTANA STATE UNIVERSITY.

THANK YOU FOR BEING HERE.

I APPRECIATE IT.

>> THANKS FOR HAVING ME.

>> AND OF COURSE WE WANT TO HEAR FROM YOU.

GIVE US A CALL, TOLL-FREE, AT 1-800-973-9800.

OR EMAIL ME AT D4K@IDAHOPTV.G.

REMEMBER, WHEN YOU SEND IN A QUESTION, YOU AND YOUR CLASS WILL HAVE A CHANCE TO WIN A D.V.

PLAYER AND OTHER PRIZES.

LET'S GO TO OUR FIRST ROUND OF EMAIL QUESTIONS.

THIS TIME FROM THE FOURTH GRADE CLASS AT CYNTHIAMAN ELEMENTARY.

STEWART WANTS TO KNOW WHY DO DINOSAURS HAVE SUCH COMPLICATED NAMES?

>> THAT'S A HARD ONE TO SAY.

WE TRY TO STANDARDIZE THE NAMES SO THAT ANY ONE AROUND THE WORLD CAN UNDERSTAND THE NAMES.

SO IF YOU SPEAK CHINESE OR FRENCH OR GERMAN, THAT WE ALL SETTLE ON, AGREE UPON ONE SINGLE NAME, SO WE USE LATINIZED NAMES, AND SO SOMETIMES THEY BECOME MOUTHFULS BECAUSE OF THAT.

>> ETHAN WANTED TO KNOW, WERE THERE CAVEMEN WHEN DINOSAURS LIVED?

>> HUMANS DIDN'T EVOLVE, CAVEMEN DIDN'T EVOLVE UNTIL MUCH AFTER THE DINOSAURS WENT INSTINCT.

SO DINOSAURS GO INSTINCT 65 MILLION YEARS AGO, AND THE FIRST HUMANLIKE PEOPLE SHOW UP ABOUT MAYBE 5 OR 3 MILLION YEARS AGO.

>> LET'S GO TO OUR FIRST EMAIL FROM SUSAN'S CLASS IN MOSCO.

JACOB AND EMILY WOULD LIKE TO KNOW HOW SMALL WAS THE SMALLEST DINOSAUR, AND WHAT IS ITS NAME?

>> MICRORAPTOR, MEANING THE LITTLE RAPTOR IS THE SMALLEST DINOSAUR.

AND IT'S NOT MUCH BIGGER THAN, OH, A MAG PIE, MAYBE A LITTLE BIGGER THAN THAT.

PRETTY SMALL.

>> PAGE WOULD LIKE TO KNOW WHAT'S THE MOST RECENT DINOSAUR FOUND?

>> THAT'S TOUGH TO SAY.

I'M TRYING TO THINK.

THERE'S BEEN SEVERAL -- THERE'S SO MANY DESCRIBED, IT'S HARD FOR ME TO KEEP TRACK OFTHOME.

I DON'T KNOW THE EXACT ANSWER TO THAT.

THERE'S BEEN A NUMBER OF DINOSAURS DESCRIBED THIS YEAR, NEW CARNIVOROUS DINOSAURS, THERE'S A NEW CARNIVOROUS DINOSAUR CALLED BASICALLY IT'S UNIQUE IN HAVING A VARIETY OF AIR SACKS WITHIN THE BONES OF THE SKELETON.

THAT WAS JUST DESCRIBED.

>> LOGAN FROM MRS.

FRYER'S CLASS IN CLEARWATER VALLEY ELEMENTARY WOULD LIKE TO KNOW, HOW DO THE BONES TURN INTO FOSSILS?

>> THAT'S A REALLY GOOD QUESTION.

IN MANY WAYS THE BONES HAVEN'T CHANGED THAT MUCH.

PEOPLE USED TO THINK THAT THE BONES WERE COMPLETELY REPLACED.

BUT YOU CAN THINK OF OUR BONES AS CONSISTING OF MINERALS, CRYSTAL STRUCTURES, THAT'S WHY IT'S GOOD TO DRINK MILK, YOU GET CALCIUM CRYSTALS IN YOUR BONES.

THAT PART OF THE DINOSAUR BONE PRETTY MUCH REMAINS INTACT.

IT GETS ALTERED A LITTLE BIT, BUT I WOULD SAY A DINOSAUR BONE IS MORE BONE THAN NOT BONE.

AND THEN ALL OF THE SOFT TISSUE, BLOOD VESSELS AND NERVES, THAT DECAYS AND THEN THAT GETS FILLED IN BY OTHER MINERALS.

AND THERE'S BASICALLY WATER WITHIN THE ROCKS THAT TRANSPORTS THOSE MINERALS IN AND THEY EVENTUALLY GROW WITHIN THOSE SPACES.

UNTIL YOU EVENTUALLY GET THE SOLID STRUCTURE THAT CONSISTS OF THE BONE AND THE MINERALS THAT WERE PART OF THE ORIGINAL BONE, BUT THEN THE OPEN SPACES ARE FILLED IN WITH ADDITIONAL MINERALS.

>> LET'S GO TO OUR FIRST CALLER.

CHEYENNE.

ARE YOU THERE?

>> Caller: YES.

>> GO AHEAD.

>> Caller: HAVE YOU EVERFOUND A FOSSIL IN A RIVER?

>> HAVE YOU EVER FOUND A FOSSIL IN A RIVER?

>> WE CERTAINLY FIND FOSSILS IN RIVER DEPOSITS.

AND OFTEN WE WALK ALONG MODERN RIVERS BECAUSE THE RIVER ERODES THE ROCKS AND EXPOSES THE ROCK.

SO I HAVE FOUND FOSSILS AROUND RIVERS.

THAT'S ACTUALLY A GOOD PLACE TO LOOK.

>> FROM MRS.

AMBER'S FIFTH GRADE CLASS, SELBY WOULD LIKE TO KNOW WHAT KIND OF FOOD DID DINOSAURS EAT?

>> PROBABLY A WIDE VARIETY OF THINGS.

PROBABLY MORE THAN WE REALLY KNOW.

WE CERTAINLY HAVE PLANT-EATING DINOSAURS AND MEAT-EATING DINOSAURS.

SOME MAY HAVE EATEN AQUATIC VEGETATION, ALMOST LIKE A DUCK.

WE FOUND REMNANTS OF THEIR BILLS THAT LOOK VERY MUCH LIKE A DUCK.

SO MAYBE THEY FED IN AQUATIC VEGETATION.

SOME MAY HAVE EATEN INSECTS.

MAYBE EVEN NUTS AND SEEDS AND THINGS LIKE THAT, AND FRUITS.

IT'S -- WE ALWAYS HAVE TO GUESS AT THAT BASED UPON THE SHAPE OF THE JAWS, AND THE SHAPES OF THE TEETH.

SO WE CAN ONLY SAY THAT THERE WAS A WIDE VARIETY OF THINGS FOR THEM TO EAT, AND THEY LIVED A LONG TIME, SO PRESUMABLY THEY ATE ALL SORTS OF THINGS.

>> YOU HAVE SOME TEETH WITH YOU.

COULD YOU SHOW THEM TO US?

>> I BROUGHT TWO TEETH.

THESE ARE BOTH FROM CARNIVOROUS DINOSAURS.

THIS TOOTH HERE IS A T-REX TOOTH.

JUST THE TOP PART OF THE T-REX TOOTH.

AND THEN THIS IS FROM ANOTHER MEAT-EATING DINOSAUR FROM AFRICA.

IT HAS A VERY NARROW SHAPE, ALMOST LIKE A BIG KNIFE BLADE WHEREAS THE T-REX TOOTH IS STOUT AND PROBABLY IT COULD SORT OF CRUNCH ON BONES AND CHEW UP BONES MORE THOROUGHLY THAN AN ANIMAL LIKE THIS ONE.

>> YOU ALSO HAVE A CLAW.

THERE YOU GO.

THAT'S A GOOD-SIZE CLAW.

>> I LIKE THIS CLAW A LOT.

WHAT'S REALLY NEAT IS THAT IT CORRESPONDS TO THE VERY END -- THIS END OF YOUR THUMB, THIS LITTLE BIT OF YOUR BONE RIGHT THERE IS WHAT THIS REPRESENTS FOR THE DINOSAUR.

>> OH, MAN.

>> YOU CAN IMAGINE JUST THE VERY LAST PART OF YOUR THUMB.

THIS IS THE SAME PIECE.

AND THE ACTUAL -- THE ACTUAL NAIL, THE PART THAT WOULD BE EXPOSEDOUT SIDE THE BODY WOULD ACTUALLY COVER THIS IN LIFE.

>> LET'S SEE IF WE CAN GET JAMIE IN BOISE.

ARE YOU THERE?

>> Caller: I AM.

>> WHAT'S YOUR QUESTION?

>> Caller: I WAS WONDERING HOW FAST DOES THE FASTEST DINOSAUR RUN THAT YOU GUYS KNOW OF?

>> HOW FAST WERE THEY?

>> THAT'S A TOUGH QUESTION.

SOME PEOPLE HAVE HYPOTHESIZED THAT BASED ON THEIR LONG LEGS THAT SOME OF THEM COULD HAVE RAN SOMETHING LIKE 40 MILES PER HOUR.

AND THEN THERE ARE OTHERS THAT PEOPLE INTERPRET AS RUNNING FAST BASED UPON THEIR FOOTPRINTS, BECAUSE THEIR INDIVIDUAL FOOTPRINTS ARE SPREAD VERY FAR APART.

IT'S A TOUGH THING TO SAY HOW FAST THEY ACTUALLY RAN, THOUGH PRESUMABLY THEY RAN PRETTY FAST.

>> FROM MRS.

AMBER'S CLASS, HANNA WOULD LIKE TO KNOW, CAN DINOSAURS CHANGE COLOR?

WHAT DO WE KNOW ABOUT THE COLOR OF DINOSAURS?

>> IT'S REALLY LARD TO SAY ANYTHING ABOUT THE COLOR OF DINOSAURS.

THEIR CLOSEST RELATIVES ARE CROCODILES AND BIRDS, AND BOTH OF THOSE ANIMALS CAN SEE IN COLOR, AND A LOT OF REPTILES AND A LOT OF BIRDS HAVE THE CAPABILITIES OF PRODUCING LOTS OF COLORS IN THEIR SKIN, DIFFERENT PIGMENTS THAT CAN MAKE THEM BLUE AND GREEN AND YELLOW.

SO DINOSAURS IN CONTRAST TO A LOT OF MAMMALS WOULD HAVE PROBABLY HAVE THE CAPABILITY OF BEING A WIDER VARIETY OF COLORS THAN MAMMALS THAT WE KNOW TODAY.

>> AND THE -- LET'S GO TO HANNA LEWISTON.

ARE YOU THERE?

>> Caller: YEAH.

>> GO AHEAD, HANNA.

>> Caller: WHAT KIND OF DINOSAURS LIVE THERE?

>> LIVED ON EACH CONTINENT?

>> Caller: YEAH.

>> OK.

LOOKING AT THE DIFFERENT CONTINENTS, WHAT KIND OF DINOSAURS LIVED IN DIFFERENT PLACES?

>> WHEN DINOSAURS FIRST EVOLVED, ALL THE CONTINENTS WERE TOGETHER.

AND AS YOU GO THROUGH THE HISTORY OF DINOSAURS, THEY ARE EVOLVE NOTHING DIFFERENT GROUPS AS THOSE CONTINENTS BREAK UP.

SO EARLY IN THE HISTORY OF DINOSAURS, THE DINOSAURS YOU COULD FIND IN NORTH AMERICA COULD YOU ALSO FIND IN AFRICA.

BUT BY THE END OF THE DINOSAUR PERIOD, ABOUT 70 MILLION YEARS AGO, THERE'S UNIQUE DINOSAURS TO EACH CONTINENT.

SO WE'D NIEPPED A UNIQUE SET OF DINOSAURS IN IDAHO, MONTANA, THAN WE WOULD IN SOUTH AMERICA.

>> CHAD FROM MRS.

FRYER'S CLASS AT CLEARWATER VALLEY ELEMENTARY WOULD LIKE TO KNOW, WHY DO DINOSAURS GO INSTINCT?

WE TALKED ABOUT THAT A LITTLE BIT IN THE VIDEO.

WHAT ARE THE THEORIES TODAY?

>> THAT'S THE BIG QUESTION.

THERE'S LOTS OF THEORIES, AND I WOULD SAY THE GENERAL CONSENSUS IS THAT EVERYTHING THAT COULD GO WRONG WENT WRONG.

SO WE HAVE CHANGES IN SEA LEVEL, THE SEA LEVEL DROPPED, AND THAT WOULD HAVE CHANGED CLIMATES.

IT ALSO WOULD HAVE AT LOUD MIGRATION OF ANIMALS FROM ONE AREA TO ANOTHER.

WE HAVE -- WE CERTAINLY HAVE VERY GOOD EVIDENCE FOR A BIG METEOR IMPACT THAT WOULD HAVE DRASTICALLY CHANGED THE EARTH OVER A SHORT PERIOD OF TIME.

THERE'S ALSO VERY GOOD EVIDENCE FOR A LONG PERIOD OF TIME OF VULCANISM.

VOLCANIC ERUPTION WERE GOING ON FOR SEVERAL MILLION YEARS, AND ALL THAT DEBRIS AND ASH THAT THEY WOULD HAVE PUT INTO THE AIR WOULD HAVE PROBABLY CHANGED CLIMATES AS WELL.

SO IT MIGHT BE THAT ALL THOSE FACTORS CAME TOGETHER, AND THAT REALLY LED TO THE END OF THE DINOSAURS.

>> LET'S TRY REBECCA IN MIDDLETON.

ARE YOU THERE?

>> Caller: YES.

>> GO AHEAD.

>> Caller: I WAS WONDERING, WHERE, WHAT, WHEN AND HOW THE FIRST DINOSAUR WAS FOUND.

>> THE VERY FIRST DINOSAUR THAT WAS FOUND.

WHAT DO WE KNOW ABOUT THE FIRST DINOSAUR?

>> THE FIRST DINOSAUR, THE FIRST TO BE DESCRIBED BY SCIENTISTS WAS FROM SOUTHERN ENGLAND, AND IT WAS DESCRIBED IN I THINK SOMEWHERE AROUND 1820 OR 1830.

AND IT WAS REALLY SORT OF A PARTIAL SKELETON.

BUT PROBABLY PEOPLE HAD ENCOUNTERED DINOSAURS, BUT HAVEN'T GIVEN THEM THE NAME FOR MANY YEARS OR HUNDREDS OF YEARS PRIOR TO THAT.

BUT THE FIRST SORT OF SCIENTIFICALLY DESCRIBED ONE CAME FROM SOUTHERN ENGLAND IN THE EARLY 1800s.

>> AGAIN FROM MR FLY'S CLASS AT CLEARWATER VALLEY ELEMENTARY, BEN WOULD LIKE TO KNOW, ARE DINOSAURS RELATED TO BIRDS OR REPTILES?

>> YOU CAN KIND OF THINK OF CROCODILES AMONG REPTILES ARE CLOSELY RELATED TO DINOSAURS.

THEY'RE SORT OF THE COUSINS OF DINOSAURS, YOU MIGHT THINK.

AND THEN BIRDS HAVE EVOLVED FROM THE CARNIVOROUS GROUP OF DINOSAURS.

SO FOR SCIENTISTS WE ACTUALLY CALL BIRDS DINOSAURS.

SO WE THINK OF THEM AS ACTUALLY BELONGING TO THE DINOSAUR GROUP.

YOU CAN THINK OF THEM AS SORT OF DISTANT DESCENDANTS OF DINOSAURS.

>> VIA EMAIL, A QUESTION FROM ISABELLA FROM MRS.

McCOY'S THIRD GRADE CLASS.

WHAT'S THE AVERAGE WEIGHT OF A T-REX?

HOW BIG DO T-REXES GET?

>> T-REXES ARE PRETTY BIG.

SCARY BIG, I THINK.

THEY ARE SOMEWHERE IN THE NEIGHBORHOOD OF 3 TO MAYBE 6 TONS.

SO SOMETHING LIKE A LARGE ELEPHANT.

>> WOW.

THAT'S A BIG, YOU DIDN'T WANT THAT IN YOUR BACK YARD.

>> NO.

NO.

>> WHAT OTHER FOSSILS DID YOU BRING?

>> I LIKE THIS ONE.

>> THAT'S ANOTHER ONE YOU DON'T WANT IN YOUR BACK YARD.

>> YEAH.

THIS IS THE HAND OF AN ALOSAURUS.

THESE ARE THE THREE FINGERS OF THAT ANIMAL.

>> WOW.

WHAT ELSE DO YOU HAVE?

>> THIS IS THE SKULL OF A VELOSORAPTOR.

>> WE HAD A QUESTION ABOUT THAT ONE.

RYAN FROM MRS.

HUNT'S CLASS WOULD LIKE TO KNOW WHERE THEY BIG LIKE IN THE MOVIE "JURASSIC PARK"?

>> THEY'RE RELATIVELY SMALL, PROBABLY NOT MUCH BIGGER THAN YOUR AVERAGE LABRADOR, LIKE A BLACK LAB OR GOLDEN RETRIEVER AS FAR AS BODY WEIGHT.

BUT THERE WERE OTHER RAPTORS THAT WERE BIGGER THAN THAT.

SO THERE'S A UTAH RAPTOR FROM UTAH, THAT WAS ABOUT THE SIDES OF THE ANIMALSN "JURASSIC PARK" OR MAYBE EVEN BIGGER.

>> BEN FROM MRS.

GRIFF'S CLASS WOULD LIKE TO KNOW, HAVE YOU EVER THOUGHT THE T-REX OR OTHER GIANT MEAT EATERS HAD FEATHERS?

>> WE HAVE EVIDENCE NOW FOR A WIDE VARIETY OF MEAT-EATING DINOSAURS AS HAVING FEATHERS.

AND THERE ACTUALLY ARE CLOSE RELATIVES OF TRIASSIC THAT HAD -- TYRANNOSAUR THAT HAD FEATHERS.

THEY WERE MUCH SMALLER THAN T-REX.

WE HAVE SKIN IMPRESSIONS OF T-REX AND ITS CLOSE RELATIVES, SO THE BIG ANIMALS IN THAT GROUP HAD KIND OF SCALY SORT OF REPTILELIKE SKIN.

BUT THEY HAD THE CAPABILITY OF PRODUCING FEATHERS.

SO THEY'RE SLIGHTLY MORE DISTANTLY RELATED ANIMALS, DID HAVE FEATHERS.

>> LET'S GO TO JACK IN MIDDLETON AGAIN.

JACK?

>> Caller: WHAT WAS E LARGEST BONE YOU HAVE EVER FOUND?

>> WHAT WAS THE LARGEST BONE THAT THE PROFESSOR HAS EVER FOUND, OR EVER FOUND IN HISTORY?

>> Caller: IN HISTORY.

>> OK.

>> THAT'S A GOOD QUESTION.

THERE ARE SOME RIBS OF BIG SARROPOD DINOSAURS THAT ARE NINE OR 10 FEET LONG.

AND I WOULD SAY THE MOST MASSIVE BONE IS THE THIGH BONE, THE FEMUR FROM, AND THOSE ARE MAYBE SEVEN, EIGHT FEET TALL.

SO REALLY LARGE BONES.

>> BAILEY WOULD LIKE TO KNOW, WHAT WAS THE BIGGEST OCEAN-DWELLING DINOSAURS?

WERE THEY IN THE WATER AS WELL?

>> Caller: WELL, SCIENTIST -- >> SCIENTISTS SEPARATE OUT DINOSAURS FROM SOME OF THE BIG REPTILES OF THE SAME TIME THAT LIVED IN THE OCEAN.

SO FOR DINOSAURS IN A VERY SORT OF SPECIFIC SENSE OR SCIENTIFIC SENSE, DINOSAURS PRETTY MUCH ONLY LIVED ON LAND.

AND THAT'S KIND OF IMPORTANT TO HOW WE DEFINE DINOSAURS.

WHEN THEY LIVE, THOUGH, THERE WERE BIG LARGE REPTILES, MARINE REPTILES, AND SOME OF THOSE GOT QUITE LARGE.

SOME OF THOSE REACHED ALMOST 100 FEET IN LENGTH.

SO YOU CAN THINK OF THEM AS COMPARABLE SOME OF THE WHALES TODAY.

>> JAKE WANTED TO KNOW, COULD THERE BE A DINOSAUR WE'VE NOT YET DISCOVERED?

>> THERE ARE ABSOLUTELY LOTS OF DINOSAURS YET TO BE DISCOVERED.

SO THERE'S NEW DISCOVERIES, NEW DINOSAURS BEING DESCRIBED EVERY YEAR.

PEOPLE ARE LOOK AT NEW AREAS, THERE'S DINOSAURS IN IDAHO THAT HAVE YET TO BE DESCRIBED.

>> STEVEN FROM MRS.

HUNT'S CLASS WOULD LIKE TO KNOW, WHAT WAS BEFORE THE DINOSAURS?

DO WE KNOW?

>> WE HAVE A PRETTY GOOD RECORD OF WHAT WAS BEFORE THE DINOSAURS DINOSAURS.

THE TRIASSIC PERIOD, WHEN DINOSAURS FIRST EVOLVED, IS VERY BUSY TIME.

THERE'S ALL SORTS OF DIFFERENT ANIMALS, AND SOME GROUPS ARE MORE CLOSELY RELATED TO MAMMALS, SO YOU CAN THINK OF AS MAMMALS' COUSINS.

THERE ARE THINGS RELATED TO CROCODILES, AND SORT OF A WIDE VARIETY OF ANIMALS AT THAT TIME.

AND THEN SOME -- SOMETHING HAPPENS DURING THE TRIASSIC AND FROM THAT POINT ON FOR THE NEXT 160 MILLION YEARS, DINOSAURS WERE SORT OF THE DOMINANT GROUP.

>> WE HAVE A LOT OF QUESTIONS ABOUT THE BIGGEST AND THE SMALLEST DINOSAURS.

WHAT'S THE BIGGEST, WHAT'S THE SMALLEST?

WE'VE TALKED ABOUT THE SMALLEST, THE MICRORAPTOR.

WHAT'S THE BIGGEST?

>> DINOSAURS RANGE FROM, YOU CAN THINK OF ALMOST A MAG PIE OR CHICKEN SIZE, TO THINGS THAT WERE 100 FEET LONG, MAYBE EVEN LONGER, MAYBE 120 FEET, SOMETHING LIKE THAT IN LENGTH.

AND MANY TONS IN SIZE.

SO MAYBE 10, 20, SOME PEOPLE SAY 40 TONS IN WEIGHT.

>> LET'S TRY TO GET -- I THINK RYAN, IS THAT YOU?

>> Caller: YES.

>> WHAT'S YOUR QUESTION, RYAN?

>> Caller: MY QUESTION IS, WHAT'S THE NAME OF THE BIGGEST DINOSAUR?

>> WHAT WAS THE BIGGEST DINOSAUR AGAIN?

>> THERE'S VERAL, SIZEMASAURUS, WHICH MEANS EARTH-SHAKING REPTILES.

THAT'S ONE.

THERE'S ARGENTINA SARURUS, A REALLY LARGE ONE AS WELL.

>> ALYSSA IN POST FALLS.

GO AHEAD, WHAT'S YOUR QUESTION?

>> Caller: HOW BIG IS A REPTILE?

>> A REPTILE?

>> Caller: YES.

>> COULD YOU DESCRIBE WHAT A REPTILE IS?

>> WHAT A REPTILE IS?

REPTILES ARE BASICALLY LIVING REPTILES INCLUDE ZARDS, SNAKES, TURTLES, AND CROCODILES.

AND THEY RANGE, MODERN ONES RANGE FROM VERY SMALL, YOU KNOW, ONLY A COUPLE INCHES LONG, TO THINGS LIKE THE NILE CROCODILE, OR THE SALTWATER CROCODILE, THAT MAY BE 15 OR 20 FEET IN LENGTH.

>> JOEY WOULD LIKE TO KNOW, IS IT TRUE THE SURGEON WAS ALIVE AT THE TIME OF THE DINOSAURS?

>> THAT IS TRUE, YES.

>> Caller: THANK YOU.

>> LET ME SEE IF I CAN GET ANOTHER EMAIL QUESTION.

FROM MRS.

McCOY'S CLASS, WHAT DO THE TRICERATOPS USE ITS HORN FOR?

>> A LOT OF PEOPLE HAVE STILL ARGUE ABOUT THAT.

SOME PEOPLE THINK THAT IT WAS USED TO, YOU KNOW, DEFEND ITSELF AGAINST PREDATORS, LIKE A T-REX.

AND THEN OTHER PEOPLE THINK LIKE ELK USE THEIR ANTLERS TODAY, THAT TH MIGHT HAVE USED IT TO WRESTLE AND SORT OF PROVE THEMSELVES AGAINST ONE ANOTHER, MAYBE ACCESS TO MATES, THINGS LIKE THAT.

SO MAYBE IN MATING BEHAVIOR, REPRODUCTIVE BEHAVIOR.

>> SPEAKING OF THAT, CAMERON WOULD LIKE TO KNOW, DID ALL DINOSAURS LAY EGGS?

>> AS FAR AS WE KNOW THEY LAID EGGS, BUT WE REALLY DON'T KNOW.

I GUESS I WOULD SAY THAT THERE'S STILL THE POSSIBILITY THAT SOME DINOSAURS MIGHT NOT HAVE LAID EGGS.

BUT WE HAVE LOTS OF EGGS FOR A VARIETY OF DINOSAURS.

>> FROM MRS.

GRIS SR.

'S CLASS WHY DO THEY USE PLASTER TO KEEP FOSSILS FROM BREAK SOMETHING THEY PUT THEM IN THE CASTS TO TRANSPORT THEM.

>> IN THE GROUND THE EARTH HAS BROKEN UP THE BONES, SO THEY'VE FRAGMENTED THE BONES, SO THEY'RE NOT -- THEY DON'T REALLY COME OUT OF THE GROUND AS ONE, NICE SOLID PIECE.

OR NOT VERY COMMONLY.

AND IT'S SORT OF JUST A WAY TO KEEP ALL THE PIECES TOGETHER, SORT OF LIKE, IF YOU HAD A JIGSAW PUZZLE YOU HAD COMPLETED AND YOU WANT TO MOVE 40 ONE TABLE TO THE OTHER, BUT IF YOU BROKE IT APART YOU'D HAVE TO DO ALL THAT WORK AGAIN.

SO IT'S A WAY OF KEEPING ALL THOSE BROKEN PIECES IN THE PROPER ORDER, AND THEN WE CAN MORE EASILY PREPARE THE BONES AND PUT THEM BACK TOGETHER.

>> HOW DO YOU KNOW WHAT'S BONE AND WHAT'S PLASTER OR DIRT OR FOSSIL?

>> SOMETIMES IT'S HARD TO TELL.

USUALLY THERE'S SOME DIFFERENCE IN THE COLOR, AND THE TEXTURE, AND THE HARDNESS OF THE MATERIAL.

SO USUALLY THERE'S A LITTLE BIT OF SEPARATION THAT THE ROCK WILL KIND OF PEEL OFF.

>> LET'S GO TO ERIC IN BOISE.

GO AHEAD.

>> Caller: OK.

I'D LIKE TO KNOW, HOW MANY DINOSAURS HAVE BEEN FOUND?

>> TOTAL NUMBER OF DINOSAURS THAT HAVE BEEN IDENTIFIED.

>> THERE'S SOMETHING LIKE 600 DIFFERENT TYPES OF DINOSAURS THAT HAVE BEEN DESCRIBED.

>> OK.

DID YOU SAY 600?

>> 600, YES.

>> WOW.

I JUST WANT TO GIVE A WARN CAN, WE'RE RUNNING OUT OF TIME.

IF YOU'RE ONLINE ON OUR PHONE LINES, STAY ONLINE.

WE'LL CATCH YOU FOR OUR WEB-ONLY PROGRAM.

YOU CAN CATCH THAT ON OUR WEBSITE AFTER THE SHOW.

SO YOU'RE IF -- IF YOU'RE ON OUR PHONE LINES, STAY THERE AND WE'LL CATCH YOUR QUESTIONS IN OUR WEB-ONLY PROGRAM.

PROFESSOR, I WANTED TO ASK YOU HOW YOU GOT STARTED LOOKING AT DINOSAURS.

WHY DID YOU WANT TO BECOME A PALEONTOLOGISTIST?

>> I HAD AN INTEREST IN ANIMALS THROUGHOUT MY LIFE.

WE HAD A FARM FOR A LITTLE WHILE GROWING UP, AND THEN I ALSO HAD AN INTEREST IN GEOLOGIC TIME.

SO THE IDEA THAT YOU COULD LOOK AT THE ROCK RECORD AND ALMOST LIKE A DETECTIVE LOOK FAR BACK INTO THE EARTH'S HISTORY.

SO I KIND OF HAD THOSE TWO LOVES AND PALEONTOLOGIST COMBINE THADZ INTEREST IN ANIMALS WITH GEOLOGIC HISTORY.

>> AND WHAT KIND OF STUDYING DO YOU HAVE TO DO TO BECOME A PALEONTOLOGIST?

>> IT REALLY COMBINES BIOLOGY, THE STUDY OF ANIMALS AND ORGANISMS AND ECOLOGY WITH GEOLOGY.

SO YOU HAVE TO UNDERSTAND ROCKS AND HOW ROCKS FORM AND THE HISTORY OF THE EARTH.

IT'S INTERESTING THAT WAY, AND IT COMBINES THOSE TWO SCIENCES.

>> I HAVE A QUESTION FROM SAMANTHA IN IDAHO FALLS.

SHE'S AT HOME WATCHING WITH HER 3-YEAR-OLD SON AND WOULD LIKE TO KNOW, IF YOU COULD PICK A DINOSAUR AS A PET, WHAT WOULD IT BE AND WHY?

>> HMM.

THAT'S A GOOD QUESTION.

I WOULD CHOOSE A SMALL ONE.

I THINK I'D CHOOSE A PLANT EATER OVER A MEAT-EATING DINOSAUR.

THERE'S SOME LITTLE ONES THAT ARE SORT OF DOG-SIZE AND EAT PLANTS.

I THINK IT MIGHT BE LIKE HAVING A PET SHEEP.

>> LILY FROM BROWNING HOME SCHOOL WOULD LIKE TO KNOW, WHAT WAS THE FIERCEST DINOSAUR?

IS THERE ONE THAT WAS REALLY -- THAT REALLY SCARED EVERYBODY?

>> WELL, THERE'S A NUMBER OF REALLY BIG MEAT-EATING DINOSAURS.

I THINK T-REX IS SORT OF THE MOST FAMOUS ONE.

THERE'S ONE FROM ARGENTINA THAT WAS EQUALLY AS BIG.

THERE'S ONE FROM AFRICA THAT WAS NEARLY AS BIG AS WELL.

SO THERE'S A NUMBER OF THEM THAT ARE REALLY LARGE AND SCARY.

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>> IT WAS A LOT OF FUN.

THANK YOU.

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