A new enigmatic hyolith from the Cambrian of West Gondwana and its bearing on the systematics of hyoliths

The genus Aladraco nom. nov. is described and discussed with two species recognized from coeval strata of the lower traditional middle Cambrian, A. schloppensis (Wurm, 1925) from the Tannenknock Formation of the Franconian Forest region, Germany, and A. ougnatensis sp. nov. from the Jbel Wawrmast Formation of the eastern Anti-Atlas, Morocco. Aladraco was formerly known as Oxyprymna Kiderlen, 1933, a preoccupied generic name that compelled renaming of the genus. The genus bears morphological characters such as the size, shape and external ornamentation of the conch which clearly indicate a systematic position under the class Hyolitha. A number of the characters, such as a tripartition into an axial chamber and lateral acuminate processes, and the course of the apertural margin, differ considerably from those seen in the two orders Hyolithida and Orthothecida and appear to indicate distinct differences in functional morphology. However, similarities of the morphological characters with th...