Silicified pedunculate kutorginate brachiopods from the Cambrian (Stage 4) of Jordan

Three exceptionally preserved, silicified and articulated complete shells with pedicles of kutorginate brachiopods are described from the Cambrian Burj Formation (latest Stage 4) of Jordan. One specimen can be assigned to Trematosia radifer (Cooper) and the others represent a new unnamed species of Kutorgina. The silicified pedicles differ significantly from those of living crown group rhynchonelliforms. In Kutorgina it is strongly annulated, whilst that of Trematosia is smooth; both taper distally and are likely much more flexible as compared with pedicles of living brachiopods. The silicified pedicles are more similar to the exceptionally preserved pedicles from other Cambrian rhynchonelliform brachiopods – like Longtancunella and Alisina. However, pedicles of the latter emerge from the ventral apical foramen rather than from the opening between the valves as in the new specimens from Jordan. Although generally similar, these two types of pedicles are unlikely to represent homologous structures. Both kutorginates possesses both an apical foramen (potentially representing a non-functional vestigial attachment) and a posterior adult pedicle. The similarities between the pedicles may be attributed to a similar type of accretionary growth from two different types of epithelia. The kutorginate-like pedicle most likely appeared early within the kutorginates and rhynchonellates.