A basal ichthyosauriform with a short snout from the Lower Triassic of China
A basal ichthyosauriform with a short snout from the Lower Triassic of China
复制标题
中国下三叠世的一种短吻基底鱼龙形动物
DOI：
10.1038/nature13866
复制
发表时间：
2015-01-22
期刊：
影响因子：
64.8
通讯作者：
Huang, Jian-Dong
中科院分区：
文献类型：
--
作者：
Motani, Ryosuke;Jiang, Da-Yong;Huang, Jian-Dong
化石记录的不完整掩盖了许多更衍生的脊椎动物分支的起源。其中一个类群是鱼翅目，这是一个出现在三叠纪早期的必然海洋爬行动物分支，没有任何已知的中间体。在这里，我们描述了一种来自中国下三叠世上部（约2.48亿年前）的基底鱼龙，其原始骨骼表明可能具有两栖习性。它比鱼翅目小，并且具有异常大的鳍状肢，可能允许有限的陆地运动。它还保留了陆生双孔类爬行动物的特征，包括短鼻子和身体躯干。与衍生性更强的鱼龙类不同，它可能是吸食器。这个新物种支持鱼龙类和湖北鳄类之间的姐妹群关系，两者形成了鱼龙形类。基底鱼龙形类仅见于中国南方，这表明该分支起源于该地区，该地区在早三叠世形成了温暖湿润的热带群岛。最古老的蜥脚类明确记录也来自该地区的同一地层单元。
The incompleteness of the fossil record obscures the origin of many of the more derived clades of vertebrates. One such group is the Ichthyopterygia, a clade of obligatory marine reptiles that appeared in the Early Triassic epoch, without any known intermediates. Here we describe a basal ichthyosauriform from the upper Lower Triassic (about 248 million years ago) of China, whose primitive skeleton indicates possible amphibious habits. It is smaller than ichthyopterygians and had unusually large flippers that probably allowed limited terrestrial locomotion. It also retained characteristics of terrestrial diapsid reptiles, including a short snout and body trunk. Unlike more-derived ichthyosauriforms, it was probably a suction feeder. The new species supports the sister-group relationships between ichthyosauriforms and Hupehsuchia, the two forming the Ichthyosauromorpha. Basal ichthyosauromorphs are known exclusively from south China, suggesting that the clade originated in the region, which formed a warm,and humid tropical archipelago in the Early Triassic. The oldest unequivocal record of a sauropterygian is also from the same stratigraphic unit of the region.