A closelook at the fossils of a group of bipedal dinosaurs known asoviraptors suggests that many species in the lineage shook theirmuscular, feather-adorned tails to gain attention during courtship.The key evidence, the scientists say, is the structure of therelatively stubby tail—muscular and flexible at its base but rigidat its tip, where the last half-dozen or so vertebrae are eitherfused together into a bladelike structure or so tightly arrangedthat they're inflexible. There's no sign that the dinos' musculartails were adorned with structures that would have rendered them aweapon. However, some fossils of early members of the group thatlived about 150 million years ago have included large feathers thatwere either attached to the last few tail vertebrae or preserved intheir vicinity, suggesting the presence of a fan-shaped display atthe end of the appendage. A new study of later species in the samelineage reveals thatthesedinosaurs had the same arrangement of tail vertebrae and themuscles used to control theirmovements,researchers reveal online today inActa PalaeontologicaPolonica. None of the fossils of those more-recentspecies of oviraptors include feathers, but those soft tissues areprobably missing because they weren't preserved, not because theyweren't there to begin with, the researchers contend. The mostlikely use for a feather-tipped tail is for courtship display, asdepicted in this artist's reconstruction of a 1.5-meter-long maleoviraptorIngeniayanshiniflirting with apotential mate.

一種兩足動物叫做竊蛋龍，對它們化石的仔細(xì)觀察表明，該譜系中的許多物種在求偶期間擺動肌肉發(fā)達的羽飾尾來獲得異性的關(guān)注?？茖W(xué)家們說，關(guān)鍵的證據(jù)在于尾巴的結(jié)構(gòu)相對短粗，根部肌肉發(fā)達而靈活，但是端部僵硬，接近端部的六七節(jié)椎骨要么連在一起形成刀刃狀結(jié)構(gòu)，要么緊湊排列而靈動。沒有跡象表明這種恐龍肌肉發(fā)達的尾巴裝飾著可以用作武器的結(jié)構(gòu)。然而，該類恐龍中生活在1.5億年前的早期成員的一些化石，擁有大片大片的羽毛，這些羽毛要么連在最后幾節(jié)尾椎骨處，要么保留在尾椎骨附近，這表明它們的尾端可以展開扇形的羽飾。今天，研究人員在《波蘭古生物學(xué)報》在線版上披露道：對同一譜系較晚物種的新研究表明，這些恐龍有著相同的尾椎骨排列以及相同的用來控制擺動的肌肉。研究人員聲稱：在竊蛋龍中，較晚物種的化石都沒有羽毛，但是那些軟組織很可能消失了，是因為軟組織沒有被保留下來，而不是因為它們一開始就不存在。這種羽飾尾最有可能的用途就是在求偶時展示自己，就像藝術(shù)家重構(gòu)圖中所描繪的那樣：一只體長1.5米的雄性竊蛋龍（Ingeniayanshini），正在跟一只可能成為配偶的雌性調(diào)情。