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Our image of dinosaurs is either of massive, benign herbivores like the Brontosaurus or of terrifyingly destructive carnivores such as the Tyrannosaurus rex. Since man discovered the first fossilized dinosaur bones in the nineteenth century, our understanding of these ancient beasts has grown in fits and starts , with many dissenting opinions among the experts. The discovery of dinosaur eggs in the Gobi Desert in the 1920s led paleontologists to the conclusion that dinosaurs had nests or lairs where they laid these eggs. A question that seemed impossible to answer was how adult dinosaurs treated these eggs and the infants that were born. However, in recent years, new research on the shedding of dinosaur teeth may have shed light on dinosaur family patterns of behavior.
The finding of a perfectly intact, massive dinosaur fossil may seem exciting, but, to paleontologists, it is just evidence that one beast died for some reason. There are often no clues as to how it died and certainly nothing to indicate any behavior patterns. However, fragments of bone, instead of a complete skeleton, mixed in with teeth, may indicate that a place very well may have been a feeding ground for certain dinosaur groups. The bones are the remains of a dinosaur buffet, and the teeth have been shed from the diners. Many species of dinosaur shed teeth quite often, and they were replaced just as easily. Paleontologists in Wyoming in the western United States have found large deposits of bones and teeth, with the teeth coming both from adults and young animals and quite possibly spread over several years.
Experts have concentrated their studies on the species called the allosaur, a forerunner of the massive Tyrannosaurus rex. The dig site is near the edge of what once was a massive inland sea in the middle of present-day North America. A great many plant-eating dinosaurs lived near the water and were prey for carnivores. Unlike many species, whose children must eat different food from adults because their teeth were undeveloped or not strong enough, allosaur young had the same teeth as their parents, albeit smaller. Teeth marks from both juvenile and adult allosaurs are on the same bones, indicating that the parents and children shared the same food hunted by the adults and brought home for the children.
The numbers of teeth of various sizes located at the dig sites suggested that the allosaurs picked a certain area, which was their main feeding place. One glaring omission from the dig sites was the teeth of juvenile allosaurs at about one third of their adult size. These teeth were found in large concentrations at other locales, possibly the site of an inland sea or lake that was reduced in size. Experts have speculated that there may have been a cycle of dry and wet seasons. During the wet season, there was plenty of food since the shores of the massive sea were near the feeding locations. A During the dry season, the waters receded, and the allosaurs had to follow their food source. B At the new source, the area for feeding was smaller, with a higher concentration of carnivorous dinosaurs, with additional dangers from crocodiles. C Bones found at these dig sites come from fish, turtles, and other aquatic animals, as the allosaur parents had to feed their young whatever they could find. D
That they could maintain one spot for so long indicates that the allosaur adults protected their young until they reached adult age. There may also have been several generations of children in the care of adults at the same time, with all allosaurs working together for mutual protection and nourishment. There were larger species of dinosaurs than allosaurs, and they could be in danger if there was intense competition for food sources. This was especially true during dry seasons. In the paleontology community, these findings are still not considered concrete proof that allosaurs and other dinosaurs fed and protected their young to adulthood. The main disagreement is over whether the teeth were deposited during feeding or merely washed to these spots from other areas. Like many other aspects of dinosaur life, it will take a long time, if ever, to get a consensus of opinion on the significance of large concentrations of dinosaur teeth and bones.
in fits and starts: not continuously
albeit: although
21. According to paragraph 1, until recently, all of the following have been discovered about dinosaurs EXCEPT:
A They lose their teeth and grow new ones.
B Their young are hatched from eggs.
C They take care of and protect their young.
D They can be either plant- or meat-eaters.
22. According to paragraph 2, finding a complete dinosaur skeleton is not as good as finding bone and teeth fragments because
A they hold some clues to dinosaur behavior
B they are more interesting to paleontologists
C they can tell us how a certain dinosaur died
D they can show how long dinosaurs lived at a place
23. The dig site that was found in Wyoming was suitable for the study of dinosaur family behavior because of
A the extreme abundance of intact dinosaur skeletons
B the large concentration of dinosaur bones with teeth marks
C the large concentration of dinosaur bones and shed teeth
D the fact that the area was once the shore of an inland sea
24. Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect answer choices change the meaning in important ways or leave out essential information.
A Young allosaurs lost their teeth as they grew closer to adulthood.
B The teeth of young allosaurs were not found at the dig sites.
C One third of all of the young allosaurs lost their teeth at some point.
D Dig sites do not contain up to one third of the adult teeth found elsewhere.
25. The word speculated in the passage is closest in meaning to
A invested
B guessed
C assumed
D discovered
26. Look at the four squares [■] that indicate where the following sentence could be added to the passage.
In fact, crocodiles have changed little since the prehistoric age and are often studied by paleontologists to learn more about dinosaur behavior.
Where would the sentence best fit?
Click on a square [■] to add the sentence to the passage.
27. It can be inferred from paragraph 4 that adult allosaurs had to
A fight other dinosaurs encroaching on their territory all the time
B fight more frequently during the dry season than the wet season
C eat fish and turtles for sustenance even during the wet season
D eat plants in small amounts if they had no other food source
28. The main reason paleontologists found the young allosaurs’ teeth in a different location than those of adults was because of
A the danger these allosaurs faced from other predators
B seasonal climatic changes that caused the allosaurs to migrate
C migratory feeding patterns took them to other places
D a desire by the allosaurs for different food sources
29. All of the following are reasons why researchers believe allosaurs may have lived in family groups EXCEPT:
A Large concentrations of teeth from different generations of allosaurs have been found in the same area.
B Allosaurs often stayed at one place for a long time to take care of their young until these became adults.
C The discovery of dinosaur eggs indicates that adult allosaurs protected them until they hatched.
D Adult and juvenile teeth marks remained on the same bones as a result of allosaurs sharing their food.
30. Directions: Complete the table below to summarize the information about prehistoric seasons as discussed in the passage. Match the appropriate statements to the season near the inland sea with which they are associated. This question is worth 3 points.
Drag your answer choices to the spaces where they belong.
To remove an answer choice, click on it. To review the passage, click on View Text .
Dry Season
Select 3
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·
·
Wet Season
Select 2
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A Allosaurs had to travel a great distance to find their food sources.
B There was less danger due to a reduced concentration of carnivores.
C Allosaurs shed their teeth more often.
D Allosaurs had to subsist primarily on aquatic food.
E The young allosaurs reached one-third of their adulthood.
F Allosaurs laid their eggs and incubated them.
G There were a greater number of herbivores available as a food source.