Ankyropteris brongniartii Renault, 1869

(Fig. 6 A-G)

This small tedelean fern is one of the best known Palaeozoic ferns (Phillips & Galtier in press); it has a wide stratigraphic range from Early Pennsylvanian to Early Permian where it was first described from Autun by Renault (1869) and from Chemnitz by Stenzel (1889) under the name Ankyropteris scandens . This fern is a vine known to have been growing on trunks of the Psaronius tree ferns.We found portions of all the different parts of the tripinnate frond in a few specimens. The primary rachis (Fig. 6A) has the characteristic H-shaped xylem strand, and a secondary rachis with the base of third order one is illustrated on Figure 6B. Foliage of this fern was found lying gently within accumulations of leaves of other plants (Fig. 6C).Tertiary rachises (R3, Fig. 6 C-E) and pinnules have been observed.Their excellent preservation reveals unknown details on the anatomy of the rather rigid pinnules (Fig. 6 C-G). Their lamina proves to be significantly thicker than in the rare examples previously described from Pennsylvanian material; the histology of the mesophyll is revealed as well as the occurrence of stomata (arrows, Fig. 6F, G). Unfortunately fertile pinnae have not been found.