All birds, both fossil and modern, have reduced the tail to a mass of fused vertebrae termed the pygostyle. |
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The tail is shortened and fused to form a pygostyle which bears tail feathers. |
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The terminal vertebrae were fused to form a structure known as the pygostyle. |
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In living birds, the remaining caudal vertebrae are fused into a further bone, the pygostyle, for attachment of the tail feathers. |
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