它们究竟是一种特殊的分支种群，还是其他各种蛇类的鼻祖？

Whether they are a peculiar sister group, or the ur-snake from which all others descend?

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这些古老蛇类的化石标本非常稀少，仅有的三个标本的后肢保存完好并可见。

There are few known fossil specimens of these ancient snakes and only three in which the hind limbs are preserved and visible.

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四个镜头记录了这种稀奇蛇类的滑翔。

Four cameras recorded the curious snakes as they glided.

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