The status of Salterella as a Lower Cambrian index fossil

Abstract

In the North American Cordillera there is strong evidence that Salterella is restricted to the medial part of the Bonnia–Olenellus Zone. Reported younger and older occurrences are attributed to either stratigraphic error or misidentification. An unnamed genus with a superficial resemblance immediately postdates Salterella, but it lacks an inner laminar cone. In the Cordillera Salterella occurs in inner detrital and middle carbonate belt strata that were deposited in the upper half of Grand Cycle B and the lower half of Grand Cycle C.In and near the Appalachian Mountains of North America and in Greenland, Spitsbergen, and Scotland, occurrences of Salterella are consistent with a medial Bonnia–Olenellus Zone age; however, this cannot be as rigorously tested as in the Cordillera, because of fewer taxa associated with the genus and in super- and subjacent strata. Outer detrital (basinal) strata of the Taconic Allochthon contain Salterella, but it is uncertain whether the fossils are of local or derived origin.Speculations that Campitius titanius Firby and Durham of California belongs in the genus Salterella are doubtful, and C. titanius is clearly older. The relationship between Salterella and Volborthella and their relative ages within the Early Cambrian are still unclear.