Ankyropteris brongniartii Renault, 1869

Galtier, Jean, Ronchi, Ausonio & Broutin, Jean, 2011, Early Permian silicified floras from the Perdasdefogu Basin (SE Sardinia): comparison and bio-chronostratigraphic correlation with the floras of the Autun Basin (Massif central, France), Geodiversitas 33 (1), pp. 43-69 : 56

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.

Figures

FIG. 6. — Silicified plants from the Permian of Sardinia:A-G, Ankyropteris brongniartii Renault, transverse sections of rachises and pinnules,all oriented with adaxial surface upwards:A, primary rachis (SAR01B1B03); B, secondary rachis with the base of a third order one (arrow) (SAR11AS01);C, connected rachises of second (R2) and third order (R3) with pinnules (arrows) (SAR01B1B02); D, third order or ultimate rachis with attached pinnules (SAR01A1B02); E, another ultimate rachis sowing the C-shaped xylem strand and attached pinnules (SAR11AS01); F, G, sections of pinnule lamina showing stomata (arrows),thick epidermis on both faces and veinlets in G (SAR01B1B01, SAR11AS01); H-I, Anachoropteris pulchra Corda, transverse sections of probable second order rachis (H) and large primary rachis (I) showing abaxially enrolled xylem strand (SAR08BB03, SAR24B02). Scale bars: A-D, I, 1 mm; E, H, 0.5 mm; F, G, 100 μm.