First report of lepidocystid echinoderm in the Cambrian of North China: Evolutionary and Palaeobiogeographic implications

Abstract

The diversification of the earliest echinoderms is “explosive” in both space and time. Lepidocystids are the most basal blastozoans and their earliest known occurrences (Cambrian Series 2) provide crucial evidence on the dispersal of early echinoderms. Here we report a new lepidocystid Vyscystis? spinosa sp. nov. based on well-preserved specimens from the Cambrian (Series 2, Stage 4) Mantou Formation in North China. Vyscystis? spinosa sp. nov. is characterized by a long aboral imbricate cup, flattened tessellate oral surface and coiled brachioles. The aboral cup is composed of imbricate plates with nipple-shaped ornamentation. Vyscystis? spinosa sp. nov. documents the first occurrence of lepidocystids in North China Block and thus contributes to increase the taxonomic diversity and global distribution of early blastozoans. Palaeogeographic analysis indicates that there are biogeographic connections among North China, west Gondwana and Laurentia in early Cambrian, and the palaeogeographic expansion in Cambrian eocrinoids precedes the taxonomic diversification.