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你好狗主 关于阅读这篇 恐龙是不是鸟的祖先
请问是不是这篇 因为这篇之前一模一样做到过 感觉有点奇怪
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 nonavian 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 findfossils 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. |
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发表于 2019-6-6 12:56:38
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