Despite being somewhat overshadowed by relatively recent reports of indisputable cycad remains from the Permian of China, the North American Upper Carboniferous and Lower Permian taxa Spermopteris and Phasmatocycas, respectively, have been of considerable interest, due primarily to their suggested status as basal cycads with links to the “pteridosperms.” According to an influential theory, cycad megasporophylls were derived from those of a Spermopteris-like ancestor via Phasmatocycas. This putative transformation entailed the phylogenetic shift of the ovules from the abaxial lamina surface of Spermopteris to the megasporophyll midrib in Phasmatocycas and extant Cycas. We have initiated a restudy of these fossils based on the original Spermopteris coriacea specimens from the Upper Carboniferous (Virgilian) Lawrence Shale described by Cridland and Morris, which are more complete and informative than previously realized, and newly collected specimens of Phasmatocycas kansana from the Lower Permian (Leonardian) Wellington Formation. We have found that the ovules of Spermopteris are attached to the midrib rather than the leaf lamina. Based on this and other characters, we propose that Spermopteris and Phasmatocycas megasporophylls are nearly identical, differing only in venation density and the height of the lamina attachment on the midrib. We also provide evidence that the apical cleft of the ovules of both forms is an original feature rather than a preservational artifact as previously suggested. Comparisons with Spermopteris reveal that the abaxial “flange” of Phasmatocycas is an artifact produced by compression of an originally inflated midrib. The implications of these new interpretations for the supposed cycadalean affinity of Spermopteris and Phasmatocycas will be discussed.

Key words: Phasmatocyas kansana, Spermopteris coriacea, Carboniferous, cycads, Permian, pteridosperms