Cambrian Hyoliths From Pengshui And Duyun, Southern China

Hyoliths, ranging from the earliest Cambrian to the Permian, are abundant in the Palaeozoic metazoa with an external skeleton consisting of a conch, an operculum and may include a pair of long, logarithmically curved "spines" called helens protruding between the conch and operculum. Conch is easy to preserve, so the classification of hyoliths always dependent on the structure of conch.And these helens arerarely preserved, and have therefore remained poorly known and enigmatic. By comparison, although Opercula remained more known, but the microstructure of the hyolithid operculum has little been reported. Based on well preserved operculum fossils, we analyzed that the conch and operculum with a double layer structure, the development of the clavicle and the bifurcation of the cardinal process.