Abstract Detail

Paleobotanical Section

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

Anatomically preserved exarch solenostelic ferns from the Cretaceous Apple Bay locality, Vancouver Island.

Two types of exarch fern rhizomes have been identified from the early Cretaceous (Hauterivian - Barremian) Apple Bay locality, Vancouver Island, British Columbia, Canada. Remains are permineralized in calcareous nodules that are studied using the cellulose acetate peel technique. Both ferns have exarch solenosteles but differ in size and a number of anatomical characters. The smaller rhizome, ca.1-2 mm wide, has a uniformly sclerenchymatous pith and cortex, and lacks trichomes or scales. This rhizome is similar to species of the fossil genus Solenostelopteris. The larger rhizome, ca. 2-4 mm wide, is represented by two specimens, o­ne of which has numerous multicellular trichomes and possible scales produced in association with branching. Ground tissues of the pith and cortex have two zones: a narrow layer of thin-walled cells adjacent to the endodermis, and a zone of thick-walled parenchyma in the central pith and in the outer cortex. There is also a layer, 1-3 cells thick, of small cells with dark contents in the outer cortex. Small diameter tracheids, with scalariform secondary wall thickenings, are arranged in isolated strands at the periphery of the stele. Endodermis, phloem and pericycle are preserved. Leaf gap production and closure impart a wavy outline to the stele in transverse section. C-shaped frond-traces diverge from the stele symmetrically and enter stipes that are more sclerotic as they become free from the rhizome. Frond traces, and sclerotic diarch roots, arise o­n all sides of the rhizome, suggesting that these represent small upright plants. The morphotaxa Solenostelopteris and Loxomopteris share characters with the larger rhizomes, but the size, upright habit, parenchymatous ground tissues, numerous trichomes, and stelar arrangement indicate that the new specimens represent a new genus of early Cretaceous derived "polypod" ferns.

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

Keywords:
Cretaceous
fern
Loxomopteris
polypod
Solenostelopteris.

Presentation Type: Paper
Session: 57-3
Location: Maybird (Cliff Lodge)
Date: Wednesday, August 4th, 2004
Time: 2:00 PM
Abstract ID:856