SPONGE SPICULES IN EARLY CAMBRIAN HETANG FORMATION, XIUNING, SOUTHERN ANHUI

We report a sponge spicule assemblage from the Lower Cambrian black shales of the Hetang Formation at Xiuning in Anhui Province, South China. Based on morphological differences, the spicules can be divided into 4 types including monaxons, biaxons, triaxons and tetraxons. In thin sections and macerated specimens, axial canal (or filament) and concentric stratification within the sponge spicules can be observed. Pyritization occurred commonly in spicules, which could play an important role for the preservation of the spicules. The Hetang sponge spicules indicate that the hexactinellids and demosponges evolved no later than the Meishucunian-Qiongzhusian (Tommotian - Atdabanian) time.