Abstract Detail

Paleobotanical Section

Rothwell, Gar W. [1], Stockey, Ruth A. [2].

Probable pteridaceous fern leaves with attached sori from the Early Cretaceous of Apple Bay, Vancouver Island.

Numerous anatomically preserved fossil ferns have been found in calcareous marine nodules from the Apple Bay locality o­n the northern end of Vancouver Island, British Columbia, Canada. The nodules are sectioned serially using the cellulose acetate peel technique. Among these mesofossils are the fertile remains of a probable pteridaceous fern. Laminae are thin, without apparent indument, and curve slightly towards the sori. The exindusiate sori lack paraphyses, appear radial, and are borne over veins with scalariform secondary wall thickenings o­n the tracheids. Sporangia arise from a short, raised receptacle, and have long narrow stalks, 2-3 cells long and up to 4 cells wide in transverse section. Sporangia have a vertical annulus and a well-developed stomium. Spores were examined by SEM using micro-preparations of single sporangia excised and delicately removed from peels using acetone washes o­n a millipore filter. The spores, 30-40 Fm in diameter, are packed tightly into the sporangia. Spores are tetrahedral, trilete, with prominent angles and an equatorial flange, with laesurae about 3/4 of the radius. The distal face of the spore has a projecting ridge with angles extending from the flange to a wide, central deltoid area. The spore surface is fairly smooth and without obvious tubercles or ridges, although the distal deltoid is slightly ridged. These spore and soral characters correspond to those found in Pteridaceae, Subfamily Taenitidoideae. Spores are most similar to Pterozonium Fée. The recent discovery of a remarkable diversity of ferns, equistetophytes, lycophytes, and mosses at the Apple Bay locality provides a unique window into the herbaceous floras of the early Cretaceous, and reveals that filicalean radiations probably occurred earlier than has been realized from either previous fossil occurrences or probability estimates of pteridophyte diversifications.

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, Edmonton, Alberta, T6G 2E9, Canada

Keywords:
Early Cretaceous
fern radiations
Pteridaceae
Pterozonium
Taenitidoideae.

Presentation Type: Paper
Session: 57-4
Location: Maybird (Cliff Lodge)
Date: Wednesday, August 4th, 2004
Time: 2:15 PM
Abstract ID:869