Secondary Cartilage Revealed in a Non-Avian Dinosaur Embryo
Secondary Cartilage Revealed in a Non-Avian Dinosaur Embryo
复制标题
DOI：
10.1371/journal.pone.0056937
复制
发表时间：
2013-02-13
期刊：
影响因子：
3.7
通讯作者：
Horner, John R.
中科院分区：
文献类型：
--
作者：
Bailleul, Alida M.;Hall, Brian K.;Horner, John R.
现存鸟类的头骨和下颌具有次生软骨，这是一种在胚胎发育过程中在关节、韧带和肌肉插入处骨形成后产生的组织。通过组织学分析，我们在非鸟类恐龙胚胎 Hypacrosaurus stebingeri（鸟臀亚科，兰博龙亚科）中发现了次级软骨。这一发现扩展了我们之前关于同一恐龙物种孵化后标本中次级软骨的报告。它提供了有关鸟类和恐龙次级软骨个体发育的第一个信息，并进一步强调了它们发育的相似性。在牙槽内的胚胎齿骨中发现了次级软骨，推测它是由于牙齿形成过程中产生的机械应力而产生的。发现了两种模式：亚冠龙胚胎中的次生软骨位置比亚冠龙孵化后的位置更受限制；鸟类胚胎和雏鸟中的次生软骨的部位比亚冠龙多得多。这表明在鸟类的进化过程中，次级软骨部位的数量有所增加。我们假设，次级软骨在精细处理食物方面具有优势，并且在从恐龙祖先的下颌进化出高度特化的鸟类喙的过程中，次级软骨比其他类型的组织/关节被选择。
The skull and jaws of extant birds possess secondary cartilage, a tissue that arises after bone formation during embryonic development at articulations, ligamentous and muscular insertions. Using histological analysis, we discovered secondary cartilage in a non-avian dinosaur embryo, Hypacrosaurus stebingeri (Ornithischia, Lambeosaurinae). This finding extends our previous report of secondary cartilage in post-hatching specimens of the same dinosaur species. It provides the first information on the ontogeny of avian and dinosaurian secondary cartilages, and further stresses their developmental similarities. Secondary cartilage was found in an embryonic dentary within a tooth socket where it is hypothesized to have arisen due to mechanical stresses generated during tooth formation. Two patterns were discerned: secondary cartilage is more restricted in location in this Hypacrosaurus embryo, than it is in Hypacrosaurus post-hatchlings; secondary cartilage occurs at far more sites in bird embryos and nestlings than in Hypacrosaurus. This suggests an increase in the number of sites of secondary cartilage during the evolution of birds. We hypothesize that secondary cartilage provided advantages in the fine manipulation of food and was selected over other types of tissues/articulations during the evolution of the highly specialized avian beak from the jaws of their dinosaurian ancestors.