First report of hexactinellid dictyosponges and other sponges from the Upper Mississippian Bangor Limestone, northwestern Alabama

Abstract

Dictyosponges from the Chesteran Bangor Limestone document the first known occurrence of these hexactinellids in Mississippian rocks of Alabama and their discovery adds information to the worldwide impoverished record of Lower Carboniferous Porifera. The sponges are generally fragmented and occur in marine, cross-bedded, sandy limestone and sandstone channel-fill lenses that occur up to 12 m above the base of the formation, above the Hartselle Sandstone. The reticulosid dictyosponges Dictyospongia(?) sp., Clathrospongia bangorensis n. sp., Clathrospongia(?) sp. A, Clathrospongia(?) sp. B, Thamnodictya(?) radiata n. sp., and Phragmodictya rugosa n. sp. are described. Previously, the lyssacinosid(?) hexactinellid Pileospongia lopados Rigby, Keyes, and Horowitz, 1979, was described from this region, from the slightly older Chesteran Monteagle Limestone, and its occurrence in the Bangor Limestone is the youngest yet discovered. In addition to the above hexactinellids, the demosponge Belemnospongia parmula Rigby, Keyes, and Horowitz, 1979, is questionably represented by a single impression in fine-grained sandstone of the Bangor Limestone.