根据传统理论，鳞片变成羽毛的第一步是先拉长，接著长出流苏般的边缘，最后产生有小钩与沟槽的羽小枝。

According to this scenario, scales became feathers by first elongating, then growing fringed edges, and finally producing hooked and grooved barbules.

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根据传统理论，鳞片变成羽毛的第一步是先拉长，接著长出流苏般的边缘，最后产生有小钩与沟槽的羽小枝。

According to this scenario, scales became feathers by first elongating, then growing fringed edges, and finally producing hooked and grooved barbules.

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