New species of Saurichthys (Actinopterygii: Saurichthydae) from Middle Triassic (Anisian) of Yunnan Province , China

A new genus and three species of Saurichthyidae, Sinosaurichthys longipectoralis, S. luopingensis and S. xinzhaiensis is described and compared with some well-known species of Saurichthys. The new taxon is represented by over hundred almost complete skeletons, collected from the equvolent of the upper member of the Guanling Formation (Anisian, Middle Triassic) in two localities: Yangjuan of Panxian County, Guizhou Province, and Dawazi of Luoping, Yunnan Province of China. The new genus of the Saurichthyidae differs from Saurichthys essentially in having peculiar dermal pectoral girdles and higher positioned pectoral fins and in the absence of the branchiostegals. The difference in the pectoral girdles and fins between the new genus and Saurichthys reflects their different loccommotion mode and ecological adptation. The new genus probably represents a linage of the saurichtyids that tended to be achieved a better ability of sustained swimming performance for cruising in surface water, like the extant needlefish. The different fin morphology between the species of the new geuns from the two fossil sites might reflect their adaptation in different habitats.