RARE Brachiopod and Primitive Echinoderm Association

Description: The discovery of the Chengjiang Biota by Hou Xian-guang in 1984 resulted in a clear window on what is 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.

Lingulella is a widespread Cambrian lingulid brachiopod, also found in the Burgess Shale. Specimens from that locality do not typically show soft tissue preservation such as the pedicle seen here. While it may have led a burrowing existence like modern-day lingulids, several have been found attached to other organisms like Eldonia and Rotadiscus, indicative of an epibenthic lifestyle. This species has been reported from both Chengjiang and Haikou.

While some researchers place the other example in the Problematica, others believe it is an early echinoderm much like the crinoids to come later. The calyx-like cap and stem found are indeed evocative of such an assignment, perhaps more than some sort of convergent evolution. Whatever the correct assignment, this is a most unusual example, and the first I have been able to secure in association with a brachiopod.