Restoration of Late Triassic Fish Trace Makers in Hengshan County, Shaanxi Province, China

It is a palaeoichnological puzzle to restore the biological morphology of the trails makers by analyzing trace fossils. Many intact fish swimming trail fossils, which can reflect some biologic features of the trace-maker fish, such as body length, distribution of fish fins, shape and structure of fish fins, have been unearthed recent years from the Late Triassic of Hengshan County, Shaanxi Province. The mathematical formulations based on the analysis of the relationship between the morphological feature parameters of trace and trace producers indicate that, the certain ratio of the distance of fish fins and body length is consistent with that of modern fish. The result of the calculation of the data from fish swimming traces shows that, the trace Undichna britannica was made by these fishes, whose distance between caudal fin and anal fin is 0. 3 of the body length, the distance between anal fin and pectoral fins is 0. 5 of the body length, and the distance between caudal fin and ventral fins is between 0. 49-0. 5 of the body length. These features are consistent with the those of a fossil fish, named Wayaobulepis zichangensia sp. nov. in the stratum in close proximity to the trace fossil. The ratio of the distance between caudal fin and anal fin, resulted from the other trace Undichna tricosta, is about 0. 35, which is similar with the features of the fossil fish named Saurichthys huanshenensis in the same stratum.