A new assemblage of pteridophyte remains from the Upper Triassic Pekin Formation of North Carolina is believed to represent the earliest unequivoval Mesozoic record of the Hymenophyllaceae (filmy ferns). The collection includes numerous fronds and frond fragments, one of which is attached to a rhizome. Individual fronds were bipinnate, delicate, and up to 20 cm long. Pinnae are alternately arranged and widely positioned, giving the frond and open appearance. Pinnules are segmented with each segment characterized by one to several rounded to elongate lobes, each of which is vascularized by a single vein. Laminae are represented by inconspicuous, light brown stains on the matrix that may be suggestive of a membranaceous organization. Most of the lobes are fertile, and each bears a marginal sorus consisting of 5 - 8 sporangia radially or helically arranged on a short receptacle that is situated at the base of a shallow, funnel-shaped indusium. Sporangia appear to be attached by short, thick sporangial stalks, or may be sessile. Although this fossil lacks the deep tubular or bivalved indusium like those of the extant representatives of Trichomanes and Hymenophyllum , the soral morphology is similar to that of early developmental stages common to both indusial types. The new specimens are compared with other Mesozoic fossils attributed to the Hymenophyllaceae.

Key words: filmy fern, Hymenophyllaceae, Mesozoic, North Carolina, Pekin Formation, Triassic