Although many lines of evidence indicate that birds evolved from ground-dwelling theropod dinosaurs, some scientists remain unconvinced. 尽管有很多证据表明鸟源自陆生兽脚恐龙,但一些科学家仍有异议。
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, where-as the fossil remains of various nonavian maniraptor theropods— the closest known relatives of birds— date only to about 115 million years ago. 他们认为,兽脚恐龙的出现较鸟类还要晚些。
But investigators have now uncovered bones that evidently belong to nonavian maniraptors dating to the time of Archaeopteryx. 但调查发现了一类兽脚恐龙的骨骼,他们于始祖鸟同代。
In any case, failure to find fossils of a predicted kind does not rule out their existence in an undiscovered deposit. 无论如何,未能发现某种推测物种的化石,并不能排除其存在于未知埋藏地的可能。
Skeptics also argue that the fused clavicles (the “wishbone”) of birds differ from the unfused clavicles of theropods. 持怀疑态度的人还认为鸟和兽脚恐龙的锁骨不同。
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. 只有在早起兽脚恐龙的锁骨被发现时,这一异议才能成立,但已有化石仅表明其锁骨类似于始祖鸟的。
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. 最后,肺有差异一点,也没有考古发现支持。
Which of the following is mentioned in the passage as an argument made by 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. 反
B. There are no known theropod dinosaur fossils that indicate the structure of those dinosaurs’ lungs. 反
C. Theropod dinosaurs appear in the fossil record about 150 million years ago. 反
D. Theropod dinosaurs did not have fused clavicles. 是论据
E.Theropod dinosaurs had certain bones that look just like those of Archaeopteryx. 反
|