Danaeopsis Heer ex Schimper 1869 and its European Triassic species

During the Middle–Upper Triassic the fern genus Danaeopsis was widely distributed in both hemispheres. Danaeopsis fronds are simple pinnate with elongate pinnae characterised by a strong midrib and secondary veins that anastomose near the margin. The sporangia of the fertile pinnae are roundish and organised in two parallel rows between the veins. From the main collections of Triassic plants in Europe more than 750 specimens belonging to this genus have been studied and this study has been implemented with literature data. After this study four different species can be distinguished in Europe, based on the angle of pinna attachment to the rachis and the venation pattern: Danaeopsis angustifolia (pinnae attached perpendicularly, almost no anastomosing near the margin), Danaeopsis marantacea (pinnae attached perpendicularly, anastomosing of secondary veins covering up to 1/3rd of the lamina), Danaeopsis lunzensis (pinnae attachment acute, anastomosing of secondary veins covering up to half of the lamina) and Danaeopsis fecunda (pinnae attachment acute, veins anastomose scarcely near the margin). From three species, D. marantacea, D. lunzensis and D. fecunda, trilete in situ spores were extracted which differ only in dimensions. Danaeopsis belongs to the Marattiaceae and represents, together with Symopteris, the ferns with the biggest fern fronds during the Middle–Late Triassic. Although no complete fronds were found so far, the fronds probably reached a length of 1–2 m.

► Danaeopsis is a typical element of the Middle–Upper Triassic on both hemispheres.
► Only four different species can be distinguished in Europe.
► Leaves of some of the Danaeopsis species could reach a length of 1–2 m.
► Fertile pinnae yielded round, trilete in situ spores with a smooth exine.