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Vertebrata Palasiatica ›› 1994, Vol. 32 ›› Issue (02): 107-126.

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NEW MATERIAL OF HSISOSUCHUS CHUNGKINGENSIS FROM SICHUAN, CHINA

Li Jinling, wu Xiaochun, Li Xuanmin   

  • Online:1994-06-15 Published:1994-06-15

四川永川重庆西蜀鳄(Hsisosuchus chungkingensis)一新材料

李锦玲, 吴肖春, 李宣民   

Abstract: Hsisosuchus chungkingensis was described by Young and Chow (1953) on the basis of a cranium and some caudal osteoderms of an old individual from the Late Jurassic Shangshaximiao Formation, near Chongqing (Chungking) city, Sichuan proVince, China. A new family, the Hsisosuchidae, was then erected for this species on the basis of a number of peculiar features, such as the closure of the suborbital fenestra, the closure of the external mandibular fenestra and the presence of a pronounced transverse ridge of the pterygoid across the palate. H. chungkingensis is as yet a poorly known taxa, because certain aspects of the cranial anatomy are obscured by extensive fusions among elements and the lack of its postcranium. A new specimen of Hsisosuchus chungkingensis, including the cranium and most of the postcranium, was collected by one of us (X.-M. Li) in early 1960s from the Jurassic sandstone of the Sangqiao area, Yongchuan county, about 60 km southwest of Chongqing. This specimen probably represents a young adult or a subadult, as indicated by its small size (less than 2/3 length of the type, based on the skull proportion) and open sutures between palatal elements. In the present paper we will redescribe H. chungkingensis in detail based on both the type and newly discovered specimens in order to clarify anatomical uncertainties, establish a suite of diagnostic features and discuss age variations of certain aspects between the type and new specimens. The close affinity of Hsisoswchus chungkingensis to the Sebecidae suggested by Young and Chow on the basis of the tooth morphology and later supported by others such as Langston (1956), Berg (1966), Kuhn (1968) has been challenged by Buffetaut (1979, 1982). A cladistic analysis on the phylogenetic relationship of H. chungkingensis within the Crocodyliformes (Clark, 1986) will be discussed in a following paper. The new material used in this study is housed in Chongqing Natural Museum (CNM V1090), Sichuan, China.

摘要: 本又详细记述了发现于四川省永川县重庆西蜀鳄(Hsisosuchus chungkingensis Young et chow, 1953)一年轻个体的不完整骨架。新材料证实了西蜀鳄为一具有眶前孔,带有边缘锯齿的牙齿,和特殊愕面结构的鳄类.通过与正模的对比,订正了一些过去的看法,如该属颅平台的形状并不如最初所认为的那样中间凸出;上颌骨不组成外鼻孔的边缘;外鼻孔的位置比正模中所记述的部位要更靠前等。在此基础上修订了该属的特征,讨论了该属年轻个体和老年个体的区别。