Campanamuta mantonaegen. et. sp. nov., an exceptionally preserved arthropod from the Sirius Passet Fauna (Buen Formation, lower Cambrian, North Greenland)

Specimens of the paneuarthropod Campanamuta mantonae gen. et sp. nov. are described from the lower Cambrian Sirius Passet Fauna of North Greenland. It is one of the most common taxa in the present collections from the Sirius Passet Fauna, being represented by some 1700 specimens (19%) of an estimated total of perhaps 8500 fossils of the collections studied. Unusually, much internal anatomy of Campanamuta has been preserved. However, interpretation of the preserved structures has been hampered by their variable appearance in different specimens and because of the degree of compression that has occurred. This paper describes the external and internal morphology of Campanamuta, and discusses the problems involved in its reconstruction. A model for the internal architecture of the animal is proposed, which recognizes the preservation of apodemes, musculature and the gut, providing the most complete picture of the internal anatomy of any Cambrian arthropod. This morphology complements that preserved in the Chengjiang and Burgess Shale taxa and adds a new source of data for the reconstruction of basal euarthropod phylogeny.