窃蛋龙摆尾求偶

 A close look at the fossils of a group of bipedal dinosaurs known as oviraptors suggests that many species in the lineage shook their muscular, feather-adorned tails to gain attention during courtship. The key evidence, the scientists say, is the structure of the relatively stubby tail—muscular and flexible at its base but rigid at its tip, where the last half-dozen or so vertebrae are either fused together into a bladelike structure or so tightly arranged that they're inflexible. There's no sign that the dinos' muscular tails were adorned with structures that would have rendered them a weapon. However, some fossils of early members of the group that lived about 150 million years ago have included large feathers that were either attached to the last few tail vertebrae or preserved in their vicinity, suggesting the presence of a fan-shaped display at the end of the appendage. A new study of later species in the same lineage reveals that these dinosaurs had the same arrangement of tail vertebrae and the muscles used to control their movements, researchers reveal online today in Acta Palaeontologica Polonica. None of the fossils of those more-recent species of oviraptors include feathers, but those soft tissues are probably missing because they weren't preserved, not because they weren't there to begin with, the researchers contend. The most likely use for a feather-tipped tail is for courtship display, as depicted in this artist's reconstruction of a 1.5-meter-long male oviraptor Ingenia yanshini flirting with a potential mate. 

 一种两足动物叫做窃蛋龙，对它们化石的仔细观察表明，该谱系中的许多物种在求偶期间摆动肌肉发达的羽饰尾来获得异性的关注。科学家们说，关键的证据在于尾巴的结构相对短粗，根部肌肉发达而灵活，但是端部僵硬，接近端部的六七节椎骨要么连在一起形成刀刃状结构，要么紧凑排列而灵动。没有迹象表明这种恐龙肌肉发达的尾巴装饰着可以用作武器的结构。然而，该类恐龙中生活在1.5亿年前的早期成员的一些化石，拥有大片大片的羽毛，这些羽毛要么连在最后几节尾椎骨处，要么保留在尾椎骨附近，这表明它们的尾端可以展开扇形的羽饰。今天，研究人员在《波兰古生物学报》在线版上披露道：对同一谱系较晚物种的新研究表明，这些恐龙有着相同的尾椎骨排列以及相同的用来控制摆动的肌肉。研究人员声称：在窃蛋龙中，较晚物种的化石都没有羽毛，但是那些软组织很可能消失了，是因为软组织没有被保留下来，而不是因为它们一开始就不存在。这种羽饰尾最有可能的用途就是在求偶时展示自己，就像艺术家重构图中所描绘的那样：一只体长1.5米的雄性窃蛋龙（Ingenia yanshini），正在跟一只可能成为配偶的雌性调情。