Burithes yunnanensis Hyolithid from Maotianshan Shales

Description: The discovery of the Chengjiang Biota by Hou Xian-guang in 1984 brought to light an exceptional largerstatte of the time known as the Cambrian Explosion. The diversity of soft-tissue fossils is astonishing: algae, medusiforms, sponges, priapulids, annelid-like worms, echinoderms, arthropods (including trilobites), hemichordates, chordates, and the first agnathan fish make up just a small fraction of the total. Numerous problematic forms are known as well, some of which may have represented failed attempts at diversity that did not persist to the present day.

This is a member of the Hyolitha, a phylum with problematic affinities, thought to be related to the mollusks. They are thought to have lived on the substrate, resting on the flatter side of the shell for stability. The two stabilizing structures are termed the Helens (named by C.D Walcott of Burgess Shale fame for his daughter). While Hyolthids are a common fossil of the Chengjiang Biota, many have not been described. This one is a member of the genus Burithes. Of all the hyolithids in the Chengjiang Biota, this taxon has the largest shell.