引用本文：赵璧,邹亚锐,陈刚,李姜丽,吴奎,万珊,徐鑫磊.2022.一件张家湾巢湖龙（双孔下纲：鱼龙型超目）标本的新认识[J].地质学报,96(3):769-782. Zhao Bi,Zou Yarui,Chen Gang,Li Jiangli,Wu Kui,Wan Shan,Xu Xinlei.2022.2022. New research progress on a specimen of Chaohusaurus zhangjiawanensis (diapsida: ichthyosauromorpha)[J].Acta Geologica Sinica,96(3):769-782.
Abstract:Chaohusaurus is a significant fossil genus with most abundant specimens and highest research level of ichthyosauromorpha in the Early Triassic, the key epoch of origin and early evolution of ichthyosaurs. However, specimens of this unique genus have only been found in limited areas, mostly in Chaohu, Anhui Province, Lower Yangtze region of South China, and a few in Yuanan, Hubei Province, northern part of the Middle Yangtze region. Based on careful restoration and observation of a reported specimen of Chaohusaurus zhangjiawanensis found in Yuanan, this study not only provides lots of cranial structure information which was largely lost in the holotype specimen, but also focuses on the comparison of the two previously reported specimens of well studied ChZhangjiawanensis and other Chaohusaurus in Anhui. The current specimen also sheds light on understanding Ch. zhangjiawanensis from comparative anatomy and functional morphology, and the ingroup evolution, ecology habitat and home range of Chaohusaurus. The result shows that, from the view of the overall proportion of skeleton and structure of cranium, Ch. zhangjiawanensisis similar to Ch. chaoxianensis and Ch. brevifemoralis found in the Anhui Province. Nevertheless, this species can be differentiated from the latter two by longer maxilla with more and stronger, densely attached teeth, inconspicuous postposition of external naris, stronger skeleton and stretch- preserved truncus. The differences in the skeletal morphology of these species may indicate different living environments. Large amounts of strong maxillary teeth and stretch- preserved truncus might be connected to its adaptive evolution which fed on highly ossified vertebrates, such as Hupehsuchia, and its living habitat in limited water with high salinity. However, it cannot be rule out that those differences could have been inherited from archaic creatures, or that they were the result of adaptive evolution towards to wider ecological habitat and more abundant food sources, or other possible reasons. In the Early Triassic, ecological environment of marine is turbulent. Dispersive ecological geographic areas (refuge) during that time may lead to the absence of gene exchange of the ichthyosaurs after its origin and early radiation, and the resulting evolution with different morphology. Further, it makes it difficult to explore the evolutionary connections of the early ichthyosaurs from the specific morphology of the skeleton. Therefore, further study on the Early Triassic ichthyosaur fossils preserved in lower beds and corresponding beds in different environments is needed.