On the occurrence of Prototaxites in the Cleveland Black Shale of Ohio, USA

Abstract

A permineralized specimen of Prototaxites Dawson collected from the Upper Devonian Cleveland Shale in Cuyahoga County, Ohio, is grayish black, resembling decorticated, petrified wood. Cellulose acetate peels and ground sections show only the medullary region, consisting of wide and narrow, densely crowded tubes, almost all running parallel, and some oblique, to the long axis of the specimen. The tubes are thick-walled, two-layered, with longitudinal furrowa on the inner surface, septate, showing successive branching, some branches anastomosing. Thin-walled septate branched filaments are present in the intertubal spaces and also cover the tubes; small areas of disintegrated tubes are present all over. Structural details of the tube wall observed with SEM, coupled with other characters, when compared with the structurally known species of Prototaxites, warrant a new name for the Cleveland specimen: P. clevelandensis sp. nov.