古生物学家在西班牙发现了一种奇特的恐龙化石，它的背上可能长了一个突出的肉冠。
（图片来源：科学网/Nature）
科学家在西班牙发现了一头食肉恐龙的化石遗迹，他们给它起了个绰号：“拉斯奥亚斯的驼背”，理由是其脊椎上的一个类似于驼峰的特征。这种正式名称为Concavenator corcovatus的恐龙从口鼻部到尾部的长度为6米。它代表了有史以来发现的名为鲨齿龙科的兽脚类（三趾）恐龙——其中最大的甚至可以提及霸王龙——的最完整的化石。科学家在9月8日的《自然》杂志网络版上强调，这种史前动物背部被拉长的椎骨可能相当于现代鸟类的羽茎瘤，后者充当了用来支撑飞羽的韧带上的锚。研究人员表示，Concavenator并没有长羽毛，但是它的驼峰可能代表了进化在这一方向上迈出的一步。
西班牙马德里市远程教育国立大学的古生物学家Francisco Ortega及其研究团队报告说，这具在西班牙中部地区发现的恐龙骨架化石保存完好。据分析这头恐龙头尾长约4米，生活在距今约1.3亿年前。其前腿尺骨上有一排整齐的点状突起，看起来很像现在鸟类羽毛根部的羽茎瘤。羽茎瘤是鸟类骨骼上长出飞行羽毛的结构，它将羽毛牢牢固定在骨骼上，对鸟类飞行能力具有重要作用。
研究人员指出，虽然以前在其他恐龙化石中发现过类似鸟类羽毛的结构，但此次发现的化石年代更早。
与其他已发现的恐龙不同，这种恐龙背上两块位置特殊的脊椎骨显示，其背上应该长有一个突出的肉冠。研究人员目前还不清楚这个肉冠的作用，有观点认为这与某些动物头顶有炫耀作用的肉冠相似，但也有观点认为它可能有更实际的作用，比如像大象的耳朵那样扇风，或像骆驼的驼峰那样储存能量。
目前，生物学界关于鸟类的进化尚存很多疑问。一种著名理论认为，最早的鸟类是由长有羽毛的小型恐龙进化而来的。（生物谷Bioon.com）
生物谷推荐英文摘要：
Nature doi:10.1038/nature09181
A bizarre, humped Carcharodontosauria (Theropoda) from the Lower Cretaceous of Spain
Francisco Ortega,fortega@ccia.uned.esFernando Escaso& José L. Sanz
Carcharodontosaurs were the largest predatory dinosaurs, and their early evolutionary history seems to be more intricate than was previously thought. Until recently, carcharodontosaurs were restricted to a group of large theropods inhabiting the Late Cretaceous Gondwanan land masses1, 2, but in the last few years Laurasian evidence3, 4, 5 has been causing a reevaluation of their initial diversification6. Here we describe an almost complete and exquisitely preserved skeleton of a medium-sized (roughly six metres long) theropod from the Lower Cretaceous series (Barremian stage) Konservat-Lagerst?tte of Las Hoyas7 in Cuenca, Spain. Cladistic analysis supports the idea that the new taxon Concavenator corcovatus is a primitive member of Carcharodontosauria6, exhibiting two unusual features: elongation of the neurapophyses of two presacral vertebrae forming a pointed, hump-like structure and a series of small bumps on the ulna. We think that these bumps are homologous to quill knobs present on some modern birds; the knobs are related to the insertion area of follicular ligaments that anchor the roots of the flight feathers (remiges) to the arm. We propose that Concavenator has integumentary follicular structures inserted on the ulna, as in modern birds. Because scales do not have follicles, we consider the structures anchored to the Concavenator arms to be non-scale skin appendages homologous to the feathers of modern birds. If this is true, then the phylogenetic bracket for the presence of non-scale skin structures homologous to feathers in theropod dinosaurs would be extended to the Neotetanurae, enlarging the scope for explaining the origin of feathers in theropods.
