We report here on a series of specimens of charcoalified sorophores with characteristics of the extant fern genus Lygodium (Schizaeaceae) collected from sediments of the Raritan formation (Late Cretaceous). Each elongate lobed fertile pinnule (sorophore) is flattened and bears alternately arranged sporangia on one surface. Each sporangium is covered by an indusium continuous with the margin of the lamina. Sporangia are oblong in shape, short stalked, and have an apical annulus formed by a single ring of radiating cells that dehiscences longitudinally. The 'sporangial cap' or 'distal face' is formed by only one cell. All of these features are characteristic of the extant genus Lygodium. Small numbers of trilete, psilate spores are found in the sporangia. Megafossils assignable to Lygodium are known from the Upper Cretaceous of North America and Germany with worldwide distribution during the Tertiary. The new Lygodium fossils are compared with others previously referred to the genus.

Fertile Lygodium sorophore Sporangia of Lygodium Trilete spore

From:

Gandolfo, M. A., K. C. Nixon, and W.L. Crepet. 2000. Fossil sorophores of the genus Lygodium. Plant Systematics and Evolution 221: 113-123.