古生物學(xué)家在西班牙發(fā)現(xiàn)了一種奇特的恐龍化石,，它的背上可能長了一個(gè)突出的肉冠。
（圖片來源：科學(xué)網(wǎng)/Nature）
科學(xué)家在西班牙發(fā)現(xiàn)了一頭食肉恐龍的化石遺跡,，他們給它起了個(gè)綽號(hào)：“拉斯奧亞斯的駝背”,，理由是其脊椎上的一個(gè)類似于駝峰的特征。這種正式名稱為Concavenator corcovatus的恐龍從口鼻部到尾部的長度為6米,。它代表了有史以來發(fā)現(xiàn)的名為鯊齒龍科的獸腳類（三趾）恐龍——其中最大的甚至可以提及霸王龍——的最完整的化石,。科學(xué)家在9月8日的《自然》雜志網(wǎng)絡(luò)版上強(qiáng)調(diào),，這種史前動(dòng)物背部被拉長的椎骨可能相當(dāng)于現(xiàn)代鳥類的羽莖瘤,，后者充當(dāng)了用來支撐飛羽的韌帶上的錨。研究人員表示,，Concavenator并沒有長羽毛,，但是它的駝峰可能代表了進(jìn)化在這一方向上邁出的一步。
西班牙馬德里市遠(yuǎn)程教育國立大學(xué)的古生物學(xué)家Francisco Ortega及其研究團(tuán)隊(duì)報(bào)告說,，這具在西班牙中部地區(qū)發(fā)現(xiàn)的恐龍骨架化石保存完好,。據(jù)分析這頭恐龍頭尾長約4米，生活在距今約1.3億年前,。其前腿尺骨上有一排整齊的點(diǎn)狀突起,，看起來很像現(xiàn)在鳥類羽毛根部的羽莖瘤。羽莖瘤是鳥類骨骼上長出飛行羽毛的結(jié)構(gòu),，它將羽毛牢牢固定在骨骼上,，對鳥類飛行能力具有重要作用。
研究人員指出,，雖然以前在其他恐龍化石中發(fā)現(xiàn)過類似鳥類羽毛的結(jié)構(gòu),，但此次發(fā)現(xiàn)的化石年代更早。
與其他已發(fā)現(xiàn)的恐龍不同,，這種恐龍背上兩塊位置特殊的脊椎骨顯示,，其背上應(yīng)該長有一個(gè)突出的肉冠。研究人員目前還不清楚這個(gè)肉冠的作用,，有觀點(diǎn)認(rèn)為這與某些動(dòng)物頭頂有炫耀作用的肉冠相似,，但也有觀點(diǎn)認(rèn)為它可能有更實(shí)際的作用，比如像大象的耳朵那樣扇風(fēng),，或像駱駝的駝峰那樣儲(chǔ)存能量,。
目前，生物學(xué)界關(guān)于鳥類的進(jìn)化尚存很多疑問,。一種著名理論認(rèn)為,，最早的鳥類是由長有羽毛的小型恐龍進(jìn)化而來的。（生物谷Bioon.com）
生物谷推薦英文摘要：
Nature doi:10.1038/nature09181
A bizarre, humped Carcharodontosauria (Theropoda) from the Lower Cretaceous of Spain
Francisco Ortega,[email protected] 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.
