Canadaspis laevigata, Unusual Shelled Arthropod from Chengjiang

Description: This unusual arthropod is known as Candaspis lavigata. This one has much soft tissue preserved, and is seen in lateral aspect. The discovery of the Chengjiang Biota by Hou Xian-guang in 1984 opened a window onto a remarkable array of lifeforms from what is termed 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.

The systematic position of this taxon has undergone several revisions. It has affinities with the younger Canadaspis perfecta, the type species. While it has been thought by some to be a crustacean, most think that is not the case, and that its primitive level of organization places it close to Fuxianhuia and its kin.