The life habits and paleoecology of middle Pennsylvanian medullosan pteridosperms based on an in situ assemblage from the Bernice Basin (Sullivan County, Pennsylvania, U.S.A.)

Abstract

The fossil flora underlying the Middle Pennsylvanian B-coal in the Bernice Basin is an in situ clastic swamp flora which contains the large-scale remains of six pteridosperm species. Petiole remains belong to four architectural types: bifurcating Neuropteris, pseudodichotomizing Alethopteris, distichous Alethopteris, and trifurcating Linopteris. Among the neuropterids, variable petiole diameters and bifurcation angles suggest that more than one Neuropteris petiole architecture existed. The rare pinnule remains support this conclusion since there are three Neuropteris foliage species present (N. rarinervis, N. ovata, and N. scheuchzeri). The swamp also contains some nearly intact pteridosperm stems up to 5 m in length. These stems belong to two taxa. One had widely separated leaves, and the other had densely packed leaves. The stems with the widely separated leaves were contorted and were not self-supporting. These plants grew in poly-specific clusters and supported each other. The stems with dense leaf packing were solitary and free standing. The plants with contorted stems reached heights of 10 m or more (excluding canopy height). The fronds reached maximum lengths of 5 m and maximum diameters of 60 mm. The self-supporting stems were shorter, probably less than 5 m in height. © 1984.