pygostyle
/ˈpʌɪɡə(ʊ)stʌɪl
/noun Ornithology
(In a bird) a triangular plate formed of the fused caudal vertebrae, typically supporting the tail feathers.The tail is shortened and fused to form a pygostyle which bears tail feathers (retrices)....
- All birds, both fossil and modern, have reduced the tail to a mass of fused vertebrae termed the pygostyle.
Origin
Late 19th century: from Greek pugē 'rump' + stulos 'column'.