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The first fossil dinosaur to be found with an intact body covering has feathers from head to tail. strengthening the view that modern birds evolved from dinosaurs, scientists say in an article published in London Wednesday, The 130 million-year-old Dromaeosaur found in China provided the best evidence that some dinosaurs developed primitive feathers, not for flight but to keep warm, according to a report in the scientific journal Nature. The Dromaeosaurs were small, fast-running predators closely related to the Velociraptor which starred in the film Jurassic Park. Like Velociraptor, they had a sickle-like claw on the middle toe, sharp teeth, and a bone structure similar to that of modern birds. The fossil was unearthed early last year by farmers digging in north-eastern China's Liaoning Province. where other feathered dinosaurs have been found. The Dromaeosanr's skeleton was found between two slabs of fine grained rock, and resembles that of a large duck with a long tail and an oversized head. indicating that it was a young specimen. Its head and tail are covered with downy fibres, while other parts of the body sprout tufts or sprays of filaments resembling primitive feathers. The backs of the arms are adorned with branched structures similar to the barbs of a modem bird feather. Dr Mark Norell, from the American Museum of Natural History, New York, head of a U. S. team examining the find with Chinese researchers, said'This fossil radically modifies our vision of these extinct animals. It shows us that ad- vanced theropod(two-legged)dinosaurs may have looked more like weird birds than giant lizards. ' Several new species of dinosaur with feather-like structures have been found in the Liaoning fossil beds since the first, Sinosauropteryx, was discovered in 1995. In most cases the fossils have been jumbled or incomplete, making it unclear how the featherlike structures related to the animal's body. Most experts now believe that modern birds evolved from dinosaurs, and cite the Liaoning fossils as evidence. Critics of the theory have, however, argued that the feather-like structures are not the remains of primitive feathers, or that the specimens are mixed-up fossils of early birds and dinosaurs. The new find may help resolve the debate. The main role of some dinosaurs' developed primitive feathers is to_____.
A.
fly
B.
fight
C.
keep warm
D.
frighten the enemy
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【简答题】血液中哪种激素出现高峰可以作为排卵的标志( )。
【单选题】在被磁化的零件上,磁场进入和离开的部位叫作()。
A.
显点
B.
缺陷
C.
磁极
D.
节点
【判断题】〈form id="form1" name="form1" method="" action="">,默认的method使用post进行值传递。
A.
正确
B.
错误
【判断题】列车或机车车辆进入股道时,在站内运行所经过的路径称为进路。
A.
正确
B.
错误
【单选题】血液中哪种激素出现高峰可作为排卵的标志
A.
雌激素
B.
孕激素
C.
卵泡刺激素
D.
黄体生成素
E.
催乳素
【单选题】血液中哪种激素出现高峰可作为排卵的标志
A.
雌激素
B.
孕激素
C.
黄体生成素
D.
促卵泡激素
【单选题】在被磁化的零件上,磁场仅如进入和离开的部位叫作:
A.
不连续性
B.
缺陷
C.
磁极
D.
节点
【单选题】血液中哪种激素出现高峰可以作为排卵的标志
A.
雌激素
B.
孕激素
C.
黄体生成素
D.
卵泡刺激素
E.
卵泡刺激素释放激素
【判断题】白蚁属于膜翅目。
A.
正确
B.
错误
【单选题】血液中哪种激素出现高峰可作为排卵的标志
A.
雌激素
B.
孕激素
C.
黄体生成素
D.
促卵泡激素
E.
促卵泡激素释放激素
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