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有个谜语请你猜一猜:尾巴像个钉,脑袋像颗豆,翅膀没有毛,有脚不会走。你一定会说:“这是我们常见的蜻蜓呀!”最古老的动物3.5亿年前,地球上就有了蜻蜓,它是地球上现有的最古老的动物之一。那时候,蜻蜓的体型很大,现在已经变小,但基本保持了原始形态,尤其是它的翅膀结构几乎没有什么变化。但是,它的3对足已明显退化,几乎不能行走。另外,蜻蜓没有折翅结构,因而不能像蜜蜂、苍蝇那样将翅膀折叠起来。
Have a riddle, guess what you think: tail like a nail, head like beans, no hair wings, feet will not go. You will surely say: “This is our common dragonfly!” The oldest animal 350 million years ago, there was a dragonfly on Earth, it is one of the oldest animals on earth. At that time, dragonfly body size is large, has now become smaller, but basically maintained the original shape, especially its wing structure almost no change. However, its three pairs of feet have been significantly degraded, almost impossible to walk. In addition, dragonflies do not have a folded wing structure and therefore can not fold their wings like bees and flies.