A Cambrian gilled lobopod from Greenland

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 Recent^1,2. 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 arthropods^5,6. 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.