A Cambrian gilled lobopod from Greenland

Abstract

THE discovery of several 'Burgess Shale'-like faunas in the Cambrian has added significant new data to the debate about the nature of the 'Cambrian explosion'. Lobopod animals have emerged as a much more important component of the Cambrian fauna than of the Recent1,2. A new lobopod-like animal, Kerygmachela kierkegaardi gen. et sp. nov., is now reported from the Lower Cambrian Sirius Passet fauna, north Greenland3. Although it shares features with other recently described lobopods, it differs in possessing lateral lobes along the body with dorsal gill-like structures attached to them, a feature that may indicate a relationship with the enigmatic Opabinia4. The presence of such a gilled lobopod suggests an evolutionary link between lobopods and the clade consisting of biramous-limbed arthropods5,6. The Cambrian lobopods thus represent a paraphyletic clade from which fully arthropodized taxa were derived. The data from Kerygmachela, when considered with recently published molecular data, may suggest a biphyletic origin for the arthropod grade of organization.