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鸟类能不能重新演化出陆地动物一样的上肢?
这事有点难啊, 你以为的鸟类只是把胳膊演化成翅膀。 抡膊向天歌,哪天不用了还能退化回来。 实际上,除了无脊椎动物这种天生的变态, 几乎所有脊椎动物想进化出某个功能, 首先要有一个凑合可以用的祖传家伙什。 进化的本质还是用则进不用则退。
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