四川自贡大山铺西蜀鳄一新种

记述了西蜀鳄一新种──大山铺西蜀鳄（Ｈｓｉｓｏｓｕｃｈｕｓ ｄａｓｈａｎｐｕｅｎｓｉｓ）,新种保存了完好的吻端,填补了西蜀鳄在这方面的缺失。新种的内鼻孔位置靠前,上颌骨和腭骨构成其边缘;眶下孔存在但较小;产于自贡市大山铺下沙溪庙组。

A NEW SPECIES OF HSISOSUCHUS FROM DASHANPU, ZIGONG, SICHUAN

A new species of Hsisosuchus is described in thes Paper. The material includes a complete skull and 1 cervical, 1 IUInbal and 7 dorsal osteoderms. It was collected from the bohanpu ~ and is housed in "gong dinosaur MuSeum (ZDM3405). Deaguosis Medium sized. Skull 380mm in length, 75mm in height and 170mm in width. The ratio of height tO length of skull about ZI%, the ratio of width tO length of saal about 45%. Snout twice as long as cudal table. A pair of external "ares sitUated in otrior end of snout. Orbit Iaper than supratempond fossa. SuborbitaJ fenests very small. Posterolatetal process of sqUamosai relatively slender. Choana anteriorly POsihoned and enclosed by maxillare and Palahne. Paroccipital Pcness lamella--like. Palatal Process of Pterygoid elongated. Frontal entering supratemporal fossa. Teeth compressed, recurved, and front and bob bothers of teeth with senations. discuS8ion The material (ZDall405) is similar tO genus Hsisosuchus in most c~ters: Medium sized; snout tWice as long as caacal table; antorbital fenesthe present orbit farce; infratomporal fenests very small; supratempolal fossa smaller than orbit Pterygoid foaling a stout transverse ridge, resulhng in a deep step betWeen itS main body and itS Palatal; ascending ProCess of jugal excluded from orbit by descending Process of POstorbital; frontal entoring supratempond fossil exoccipital foeing a pronounced ~verse ridge above formen inagnum; Teeth compressed, recurved, and front and back bothers Of teeth with senations. Accowhng to the above feabes the material (ZDall405) is refer able tO genus Hsisosuchus. In comparison with Hsisosuchus chungbeensis, Hsisosuchus dashanpuensis is differellt in the following feares: Choana anteriorly posihoned and enclosed by maxillary and Palatine; suborbital fenestla small; POsterolateral Process of sqUamosal relahvely slendef; Paroccipital process lamella--like; Palatal Process of pterygoid elongated. On the contlary, choana entirely wilson Palatine; suborbital fenesthe closed; Presence of an elongated POsteromedian depression betWeen nasals; POsterolareral Process of sqUalnosal exbewhmp large; Paroccipital process shoal Palatal Process of pterygoid short in Hsisosuchus chungbogensis.