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Dragons and Dinosaurs. Main selection with comprehension questions. Prehistory Mystery
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Dragons and Dinosaurs Main selection with comprehension questions
Prehistory Mystery Ancient people had their own ways of explaining the strange bones they found. They thought the bones were the remains of giants, dragons, sea monsters, and other creatures you read about today in fairy tales and myths.
Consider the legend of the griffin, a fantastic cross between a lion and an eagle once believed to live in the deserts of China. People all over the ancient world—Asia, the Middle East, and Greece and Rome—told stories of these griffins. Each culture imagined them differently, but most ancient art shows them with gigantic beaks, claws, wings, and catlike bodies. Why do you think so many cultures had legends about the same imaginary creature?
Now take a look at the skull of a small dinosaur we call Protoceratops. Scientists have found many of these skulls in the Gobi desert in Mongolia (a region of China), where Protoceratops lived about 80 million years ago.
Protoceratops had a huge, birdlike beak designed to chop up the plants it ate and to defend itself. A large “frill” on its head and bony bumps on its cheeks (probably both a form of protective armor) give its skull a monstrous look.
Ancient people who saw these skulls guessed that they were the remains of winged, lionlike birds that guarded gold in the desert mountains. They thought they were griffins. In what ways was Protoceratops similar to the griffins imagined by ancient cultures? In what ways was it different? What is the “Prehistory Mystery” described on pages 674-675?
When you look at its skull, it’s easy to see why people once thought Protoceratops was a fantastic birdlike creature.
The ancient people were not far from the truth. These were the bones of amazing creatures, though not human giants, nor dragons, nor griffins. In the 1800s, scientists began to recognize that ancient bones and fossils belonged to long-extinct animals, which no one, of course, had ever seen. The mystery deepened. What correct conclusion did ancient people draw about dinosaur bones?
What did these animals really look like? The task of arranging the bones in the proper order and accurately imagining the flesh and muscle that covered them was quite a challenge.
The Terrible Lizards Pretend for a moment that you have never seen a bicycle before. You have no idea what it does or how it is used.
Now suppose you stumble upon a funny-looking triangular leather thing sticking out of the earth. Next to it lies a curved metal bar with plastic ends. Farther along, a piece of rubber.
What could these things be? Are they parts of a single contraption? Are they related to anything you know about? How do they fit together? How many, and what, pieces are missing? What point is the author making when she talks about bicycles and their parts? Do you think the author’s discussion of bicycle parts helps readers better understand the text? Explain.
This gives you an idea of the questions scientists ask when they find dinosaur bones. Just over a hundred years ago, the first scientists to study them thought these bones belonged to gigantic, ferocious lizards that once roamed the earth. What did the first scientists to study dinosaur bones figure out?
A brilliant English scientist named Richard Owen recognized that these creatures were different enough from modern reptiles to deserve their own name. He called them dinosaurs, from the Greek for “terrible lizard.”
Though Owen was correct to group them under one name, he didn’t realize that some dinosaurs were small and harmless. And though dinosaurs belong to the reptile family, they are very different from lizards.
Iguanodon was among the first dinosaurs to be scientifically described. Its discoverer, Gideon Mantell, believed that the very large teeth and bones he found must have belonged to a huge iguana-like creature whose legs sprawled out to the side like those of a lizard. Mantell thought that the large pointed object his wife discovered was the creature’s nose horn.
Over the years, scientists changed their minds many times about the appearance of Iguanodon. Today we know that it had four straight legs, like a mammal, and could walk either on two hind legs or on all fours. That spiky object mistaken for a horn was really a long, sharp toenail.
Today scientists believe Iguanodon held its tail straight behind it and walked mostly on all fours.
The Case of the Deceptive Dinosaur Today we know of more than 1,000 species of dinosaurs, and others are being discovered every year. Paleontologists, scientists who study bones and fossils to learn about the past, have a tough job keeping up with all the bones. When bones are first discovered, it is sometimes difficult to know what animal they belong to. What does the author mean when she says that paleontologists have a hard time “keeping up with all the bones”?
Is it a new dinosaur or one we already know about? And when the bones of more than one creature are jumbled together, scientists must be careful to separate and identify each animal.
Take the case of poor old Apatosaurus (whose name means “deceptive lizard”). Now there’s a dinosaur with an identity crisis. This huge 30-ton creature was first discovered and named in 1877. Two years later, the same scientist examined another set of Apatosaurus bones and thought they belonged to a different type of dinosaur, which he named Brontosaurus (or “thunder lizard”).
With its long graceful neck and whip-like tail, Brontosaurus became a familiar favorite among dinosaur lovers. But, in 1974, scientists decided that Brontosaurus was really Apatosaurus—that there was no Brontosaurus after all. Is “The Case of the Deceptive Dinosaur” a good heading for this section? Why
To make matters worse, Apatosaurus lost its head. Honestly. Because the original skeleton was found without a head, no one was sure what Apatosaurus’s skull looked like. For nearly 100 years, models and drawings in museums all over the world showed it with no head or the wrong head. Finally, the skull was located in a museum basement, and Apatosaurus could once again hold its head up proudly.
We finally have a complete picture of Apatosaurus, but there’s a lot more to learn.
Or maybe not. Recent evidence indicates that Apatosaurus and other dinosaurs with long, elegant necks may not have been able to lift their heads far off the ground. For many years, experts believed that these vegetarian dinosaurs reached their necks into the treetops to dine, like giraffes.
Recently, however, computer modeling has revealed that the positioning of their neck bones would have prevented them from raising their heads any higher than about 12 feet. While it may have been able to rear up on its hind legs to snag treetop treats, more often Apatosaurus probably reached its long neck across creeks or other obstacles as it grazed for food along the ground. How have scientists learned about Apatosaurus from computer modeling?
Computer Images To create these images of Apatosaurus and its neck movements, scientists entered information about the size, number, and positioning of the animal’s neck bones into a computer, which figured out just how far the dino could move its neck up and down and sideways.
Noisy Tails? What would you do with a 50-foot, 3,500-pound tail? Scratch your own nose? Go fishing? Apatosaurus may have had a better idea. Computer modeling shows that these dinosaurs could have cracked their tails like a whip. Three feet thick at the body, the tail thinned to a narrow tip about the width of a human thumb. As the dino lashed it, a wave of energy would have traveled down to the tip, arriving at a speed faster than that of sound—more than 750 miles per hour.
When something moves that fast it “breaks the sound barrier,” creating a loud noise. A cracking dino tail would have made a huge, thundering clap—loud enough, perhaps, to scare off an enemy. But some scientists think that such supersonic tail wagging is unlikely because it would have hurt or damaged the dino’s tail. After all, they remind us, just because the computer says it was possible doesn’t mean it actually happened that way. According to what scientists have found out about Apatosaurus’s tail, what else do you think it might have been used for?
Listening to the Bones Computers have become a valuable tool to help paleontologists picture dinosaurs better. Scientists can now even hear what dinosaurs might have sounded like. Consider Parasaurolophus, an odd-looking fellow. A large, bony crest extended from the top of its head back over its shoulders. Handsome, perhaps, but what did the crest do? Some scientists think it may have been a weapon or even a snorkel, but no evidence supports these ideas.
How about a trombone? When a nearly complete Parasaurolophus skull was found in New Mexico, computer scientists and paleontologists joined forces to see if the head crest might actually have been a noisemaker. What is the main idea on page 682? What detail supports this idea?
Snorkeling Brachiosaurus Apatosaurus and its cousins—the “long-necks”—weighed more than any other creature that ever lived. For a long time, scientists thought that the only way these huge animals could move their massive bodies must have been in the water. Their long necks would keep their heads up so that they could breathe as they walked along a lake or river bottom, grazing on soft aquatic plants.
But modern scientists wondered: wouldn’t the water’s pressure collapse the great creature’s lungs and disable its heart? Probably so, which made scientists imagine that the long-necks may have wandered on land after all.
New research reveals yet another possibility. Sometimes, along “trackways” where dinosaur footprints have been preserved, scientists find only front footprints. In ancient times, these trackways may have been underwater. Could the long-necks actually float, touching the bottom with only their front feet? That way, they could live in water without their giant bodies being deeply submerged.
Computer modeling shows that this may have been possible, especially since we now know that the creatures had tiny air sacs along their spines that would help them stay afloat. The catch? If they lost contact with the bottom, they would probably tip over. How did computer modeling help scientists determine where long necks probably lived? How have scientists’ ideas about long-necked dinosaurs changed over the years?
They took scans of the inside of the crest with special imaging equipment so that they wouldn’t have to break it open. Then they used the scans to model a three-dimensional image of the crest. They found that it was filled with a complicated series of hollow tubes and chambers.
When the computer created the sounds made by blowing air through the crest, the scientists heard an eerie, deep rumbling tone. Were the scientists hearing a sound not made on earth since the dinosaurs lived here? Who can know?
