A CORSET-LIKE FOSSIL FROM THE CAMBRIAN SIRIUS PASSET LAGERSTATTE OF NORTH GREENLAND AND ITS IMPLICATIONS FOR CYCLONEURALIAN EVOLUTION

摘要

A large (maximum length 80 mm), tubular, corset-like problematic fossil from the early Cambrian (Cambrian Series 2, Stage 3) Sirius Passet Lagerstätte of North Greenland is interpreted as the lorica of an ancestral loriciferan. In addition to the double circlet of 7 plates composing the lorica, Sirilorica carlsbergi new genus, new species also preserves up to six multicuspidate cuticular denticles that are similar in shape to the pharyngeal teeth of priapulid worms, although their location is suggestive of scalids. Whilst traditionally placed as a sister group of priapulid worms within Vinctiplicata (Scalidophora), recent molecular sequence data suggest that loriciferans might be more closely related to nematomorphs. The limited morphological information available from Sirilorica is consistent with this interpretation, placing the Sirius Passet fossil within the total-group of Loricifera, within the Loricifera + Nematomorpha clade.