Stockey, Ruth A. , Rothwell, Gar W. , Little, Stefan A. .
Dipteridaceous ferns from the early Cretaceous Apple Bay flora of Vancouver Island.
Anatomically preserved foliage of a dipteridaceous fern has been identified in both calcareous nodules and fine-grained limestone sediments from the early Cretaceous (Hauterivian - Barremian) Apple Bay locality from Vancouver Island, British Columbia, Canada. Fronds with attached sori containing spores are preserved as both compression/impressions and as permineralizations that are studied using the cellulose acetate peel technique. The stipe bifurcates forming two laminar segments with paired teeth along the margin. Several orders of veins occur in the lamina; major veins that dichotomize to the lamina edge, and finer veins that reticulate, forming rectangular areoles, some with freely ending veinlets. Veins are enclosed by sclerenchymatous sheaths that extend both abaxially and adaxially. Vein extensions are abaxially prominent, producing concave areas between veins, imparting an undulating appearance to the leaves in transverse section that can also be seen in surface view on compressions. Adaxial cuticle is thick and the epidermis is composed of rectangular cells with undulating walls. Stomata are found only on the abaxial surface. Loosely aggregated exindusiate sori are found scattered across the lamina in the concavities formed by the overarching sclerenchymatous vein sheaths. Sori, found within the areoles, have sterile paraphyses and sporangia with short stalks that are 4(-6) cells wide throughout their length. Sporangia have a vertical to slightly oblique annulus that is interupted by the stalk and trilete spores that are often collapsed. Leaf morphology is similar to that seen in extant Dipteris novo-guineensis and fossil Hausmannia spp. The association of these ferns with small delicate moss gametophytes, fern sporelings and vegetative remains of Lycopodium and Selaginella reinforce the interpretation that deposits containing fossil dipterids indicate disturbed environments and storm conditions.
1 - Ohio University, Department of Environmental and Plant Biology, Porter Hall, Richland Avenue, Athens, Ohio, 45701-2979, USA
2 - University of Alberta, Department of Biological Sciences, CW 405 Biological Sciences Building, Edmonton, Alberta, T6G 2E9, Canada
Presentation Type: Paper
Location: Maybird (Cliff Lodge)
Date: Wednesday, August 4th, 2004
Time: 3:00 PM