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Ceratopsia Ceratopsia thrived in North America and Asia

游客2024-01-04  21
问题                     Ceratopsia
    Ceratopsia thrived in North America and Asia during the Cretaceous Period (about 146 to 65.5 million years ago). Their name means "horned face" and indeed many of them did feature bony horns projecting from their skulls.
(A) The horns may look quite predatory, but Ceratopsians were herbivores1, so their horns were defensive in nature and may have been used to enforce order in the group.
(B) Not all Ceratopsians had horns, but all had beaklike mouths.
(C) The fossil record has revealed three distinct families among Ceratopsia: Psittacosaurids, Protoceratopsids, and Ceratopsids. Triceratops, a member of the Ceratopsid family, is probably the best known species of Ceratopsia. With its facial horns and neck display, it exhibits many of the features commonly associated with this dinosaur group.
(D) However, there are species of Ceratopsia that are quite different from the familiar Triceratops.
    The Psittacosaurids comprise the Psittacosaurus genus2 and the Hongshanosaurus genus. Although not much fossil data are available for Hongshanosaurus, comparisons with Psittacosaurus can be made. Evidence indicates that both were roughly deer-sized bipeds dwelling in East Asia. Hongshanosaurus had beak points on both upper and lower jaws, while only the upper jaw of Psittacosaurus was pointed. Much more fossil evidence is available for Psittacosaurus species. At least one species had long quills along its back and tail. Researchers speculate these quills were used for display during mating or fighting. As early Ceratopsians, the Psittacosaurids had many anatomical features that would show up in similar or interestingly modified forms in later species, but none of the Psittacosaurids had the neck frills or facial horns that came to be associated with the Ceratopsians.
    Although their name suggests that the Protoceratopsids were the first of this dinosaur group to have horned faces, they, in fact, lacked the well-developed horns of later species. While they more closely resembled the Ceratopsids on the whole, they were still relatively small and hornless. Protoceratops, a six-foot-long quadrupedal herbivore, is a representative Protoceratopsid. Fossil examples found in China and Mongolia show that it had a turtle-like beak and a neck frill, a version of which would show up among the more familiar Ceratopsids. While Protoceratops did have some knobby points on its skull, the points only slightly hinted at the impressive horns that appeared on the Ceratopsids.
    With the arrival of Triceratops and other advanced Ceratopsids, Ceratopsia reached new levels of sophistication, variety, and size. All Ceratopsid fossils have been found in western North America and reveal that they were quadrupedal herbivores with beaked jaw tips and rows of teeth specialized for shearing. The family featured a remarkable array of horns, neck frills, and spines. These neck frills, manifesting in various shapes and sizes, probably were too thin to be practical as a defense against predator species, and researchers speculate that they were used during mating displays, for anchoring jaw muscles, for regulating body temperature, or for a combination of these purposes. Most Ceratopsids had two long brow horns and a short horn on the nasal ridge. Because the Ceratopsids were vegetarian and fairly large (up to 30 feet long and 10 feet tall), researchers think that the horns, along with the neck frills, largely served functions of competition, whether in displays or combat. Moreover, since intraspecific conflicts often are tests of strength rather than fights to the death, thin neck frills may have been sturdy enough to provide some protection during such confrontations.
    There is evidence of Ceratopsian species that do not neatly fall into the familial categories as described. While these species appear closely related to Ceratopsia, they tend to be smaller and more primitive. Researchers have debated over recognizing a distinctly new Ceratopsian family or grouping these misfit species with an existing family. Psittacosaurids, Protoceratopsids, and Ceratopsids are the commonly accepted Ceratopsian families with established member species and defined characteristics. Despite some controversies over minor species, a view of the Ceratopsian families is a view of fascinating adaptations and development in a unique dinosaur group. [br] The word "it" in the passage refers to
选项 A、Protoceratops.
B、Protoceratopsid.
C、Mongolia.
D、version.
答案 A
解析 指代关系题 指示代名词所指代的名词一般出现在指示代名词所属的句子中或者其前面的句子中。本文中指示代名词所属的句子里没有可以替换it的名词，所以要在前面的句子中找。前面的句子是“Protoceratops, a six-foot-long quadrupedal herbivore, is a representative Protoceratopsid.” it指代的是protoceratops还是protoceratopsid呢?一般情况下指示代名词用作主语时，指代其前一句的主语，因此答案是A项。
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