2017年6月GMAT阅读机经（7.1）（四）.

　　第六篇 鸟类祖先

　　一直以来的观点认为鸟的祖先是恐龙。但是有人反驳说有一种老鸟的化石被发现比所有现在发现的恐龙化石都年代久远。。。。最后又说这样也不能证明恐龙不是鸟的祖先，因为也没有证据证明将来不会有更老的恐龙化石被发现vc2010

　　一道是鸟的祖先是谁的~GWD原题(原文!原题!不是变体!!我确定!)谢谢Hanah同学!

　　Although many lines of evidence indicate that birds evolved from ground-dwelling theropod dinosaurs, some scientists remain unconvinced. They argue that theropods appeared too late to have given rise to birds, noting that Archaeopteryx lithographica – the oldest known bird – appears in the fossil record about 150 million years ago, whereas the fossil remains of various no avian maniraptor theropods – the closest known relatives of birds – date only to about 115 million years ago. But investigators have now uncovered bones that evidently belong to nonavian maniraptors dating to the time of Archaeopteryx. In any case, failure to find fossils of a predicted kind does not rule out their existence in an undiscovered deposit. Skeptics also argue that the fused clavicles (the “wishbone”) of birds differ from the unfused clavicles of theropods. This objection was reasonable when only early theropod clavicles had been discovered, but fossilized theropod clavicles that look just like the wishbone of Archaeopteryx have now been unearthed. Finally, some scientists argue that the complex lungs of birds could not have evolved from theropod lungs, an assertion that cannot be supported or falsified at the moment, because no fossil lungs are preserved in the paleontological record.

　　T-4-Q5-Q7

　　The primary purpose of the passage is to

　　A. compare the development of two hypotheses concerning the evolutionary origin of birds

　　B. suggest revisions to the standard theory of the evolutionary history of birds

　　C. evaluate the usulness of fossil evidence in determining the evolutionary history of birds

　　D. challenge the theory that birds evolved from ground-dwelling theropod dinosaurs

　　E. respond to criticisms of the theory that birds evolved from ground-dwelling theropod dinosaurs

　　In the context of the passage, the phrase “fossils of a predicted kind”(line 16) most likely rers to which of the following?

　　A. Theropod fossils with fused clavicles

　　B. Theropod fossils that are similar in structure to Archaeopteryx fossils

　　C. Theropod fossils dating back more than 150 million years

　　D. Fossils indicating the structure of theropod lungs

　　E. Fossils indicating the structure of Archaeopteryx lungs

　　Which of the following is mentioned in the passage as an argument madeby scientists who are unconvinced that birds evolved from theropod dinosaurs?

　　A. There are no known theropod dinosaur fossils dating from a period after the time of Archaeopteryx.

　　B. There are no known theropod dinosaur fossils that indicate the structure of those dinosaurs’lungs.

　　C. Theropod dinosaurs appear in the fossil record about 150 million years ago.

　　D. Theropod dinosaurs did not have fused clavicles.

　　E. Theropod dinosaurs had certain bones that look just like those of Archaeopteryx.