Sedimentary environment of Late Cretaceous theropod tracksite in Qiyun Mountain, Anhui Province

Qiyun Mountain theropod tracks from Anhui Province seem to be the best preserved tracks in several kinds of Late Creta-ceous tracks. The study of their sedimentary environment provides evidence for restoring the habitats of dinosaur fauna. All of the tracks are natural theropod casts, preserving Palaeophycus tubularis and Scoyenia sp., which indicates a shallow water in continental deposits. The thin section analysis reveals that the footprint layers are dominated by lithic sandstones. The four grain characteristic pa-rameters consisting of average size, standard deviation, skewness and kurtosis for the sandstones are consistent with features of the typi-cal fluvial deposits. Grain size distribution histogram, probability cumulative curves and scatter plots of footprint layers present the smaller particles and weaker hydrodynamic conditions upwards. The sedimentary environment displays the transformation from river-beddeposits to point bar deposits. Therefore, the sedimentary environment of Qiyun Mountain theropod tracksite was large meander-ing river deposition. Tracks were preserved in the lower part of point bar deposits which was the water source of the theropod fauna under the Late Cretaceous dry climate conditions.