Pachypteris (Brongn.) T.M.Harris. is a Mesozoic pteridosperm leaf fossil probably belonging to the seed fern Order Peltaspermales. Pachypteris is represented by hypostomatic, bipinnate or unipinnate leaves, with alethopteridian venation (midvein and secondary veins divided once or twice before reaching the pinnule margin), pinnules with entire margins and rounded apices. The stomata are haplocheilic, monocyclic or dicyclic, usually depressed, with the guard cells occurring in the lowermost part of the stoma.