ABSTRACT

Tail elongation is a trait common to many sauropod dinosaurs. In certain members of Diplodocidae, for example, the total caudal vertebrae count is as high as 70 to 80 bones, making a total estimated tail length for mature animals that is in excess of 10 metres. A number of competing hypotheses have been suggested to explain the function of this ‘hyper-elongate’ tail including use as a counterbalance, use as a defensive weapon, use as a sonic-boom-generating ‘bull-whip’ or use as a feature for sexual display. Here, a new hypothesis is presented for the function of sauropods’ hyper-elongate tails – herding co-ordination. Many sauropods are known, from multiple independent lines of evidence, to have been herding animals that moved in large groups over wide ranges; it is proposed that the elongation of the tails in many of the more massive sauropod lineages may have evolved to allow for simple and efficient communication between individuals via near continuous animal-to-animal contact during herd movement and migration. This contact, it is suggested, would have facilitated speedier, more compacted and more efficient mass movement of the animals as a group, and reduced the need for continual slowing and stopping to maintain herd formation.

Institutional abbreviations: AMNH: American Museum of Natural History, New York, USA; CM: Carnegie Museum of Natural History, Pittsburgh, USA; HMN: Natural History Museum, Berlin, Germany; OMHN: Sam Noble Oklahoma Museum of Natural History, Oklahoma, USA

摘要

尾巴伸长是许多蜥脚类恐龙的共同特征。例如，在梁龙科的某些成员中，尾椎骨总数高达 70 到 80 块骨头，因此估计成熟动物的尾巴总长度超过 10 米。已经提出了许多相互竞争的假设来解释这种“超长”尾巴的功能，包括用作平衡装置、用作防御武器、用作产生音爆的“牛鞭”或用作特征用于性展示。在这里，对蜥脚类恐龙超长尾巴的功能——放牧协调提出了一个新的假设。许多蜥脚类恐龙从多个独立的证据中得知，它们一直在放牧大范围内大群移动的动物。有人提出，在许多更庞大的蜥脚类动物谱系中，尾巴的伸长可能已经进化到允许个体之间通过在畜群移动和迁徙期间近乎连续的动物与动物接触进行简单有效的交流。有人认为，这种接触会促进动物作为一个群体的更快、更紧凑和更有效的群体运动，并减少持续放慢和停止以维持群体形成的需要。

机构简称：AMNH：美国自然历史博物馆，纽约，美国；CM：美国匹兹堡卡内基自然历史博物馆；HMN：德国柏林自然历史博物馆；OMHN：山姆诺布尔俄克拉荷马自然历史博物馆，美国俄克拉荷马