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RESEARCH PRODUCT

A New Early Cambrian Lobopod-Bearing Animal (Murero, Spain) and the Problem of the Ecdysozoan Early Diversification

subject

description

A new xenusian, Mureropodia apae gen. and sp. nov., is found in the lower Cambrian of the Murero Lagerstatte in the Cadenas Ibericas, NE Spain. In Mureropodia, the lobopod length/body width ratio reveals that this animal hardly was able to walk on the bottom surface. Possibly, it could use the limbs for anchoring the body to the substrate. A well-developed dermomuscular sac of circular and longitudinal muscular systems as well as probably retractile proboscis fit such an interpretation. The ground plan of the Xenusia includes a vermiform body; a proboscis or mouth cone; paired lobopods with claws; a cuticle displaying a repeated anatomical patterning; a straight digestive tract with terminal mouth and anus. Morphologically heterogeneous xenusians, which crawled with their lobopods along the bottom, might give rise to four morphofunctional lineages – to cephalorhynch worms by adaptation for burrowing with retractable proboscis; to tardigrades by adaptation for interstitial habitat; to euarthropods by adaptation to walking on joint appendages; and to anomalocaridids by adaptation to swimming with lateral flaps.