The problematic Hadimopanella, Kaimenella, Milaculum and Utahphospha identified as sclerites of Palaeoscolecida

Abstract

Hadimopanella Gedik, 1977, Kaimenella Marss, 1988 and Milaculum Mueller, 1973 have been established on the basis of isolated elements of unknown origin. Recently, the latter genus has been tentatively related to the Agnatha (van den Boogaard 1988). By contrast, Bendix-Almgreen and Peel (1988) assigned Hadimopanella to the chordate stock but definitely excluded it from vertebrates. Well-preserved worm-like organisms of Palaeoscolecida Conway Morris and Robison, 1986 are known from the Lower Cambrian to the Lower Ordovician. They have their outer surface covered with a pattern of sequin-like sclerites which evidence the systematic affiliation with the isolated sclerites mentioned above. Based on similar structures on the outer surface, Utahphospha Mueller and Miller, 1976 is considered to belong to the same group.