但是，哪种具有四肢的近亲及其特征导致了向无四肢的蛇的进化呢？

But which four-legged relatives and their family traits led the transition for legless snakes?

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爬行动物，身体细长，体上有鳞，无四肢。种类很多，有的有毒，有的无毒。以蛙、鼠为食，大蛇亦吞食大兽类。

Reptiles, body slender, scaly body, no limbs. Many types, some toxic, some non-toxic. With frogs, rats for food, the serpent has swallowed a large animal.

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这张图片来自费城穆特博物馆的收藏，展示一位无肢畸形的小姑娘，这一种疾病的特点是四肢未充分发育。

This image, from a collection at Philadelphia's Mutter Museum, shows a young girl with amelia, a condition marked by undeveloped limbs.

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