他们认为，开始适应水生生活的陆地动物很快就会变成既不是鸟也不是鱼，无法在任何一种环境中生存。
They contended that land animals that began to adapt to aquatic life would soon be neither fowl nor fish, incapable of surviving in either medium.
一旦自然选择塑造了植物的适应机制，使之克服在陆地生活的障碍，植物物种就生机勃勃且丰富多样了。
Once natural selection had shaped the adaptations that helped plants overcome the obstacles to terrestrial living, plants prospered and diversified.
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