Hillier, Kaitlin , Rothwell, Gar .
Evidence for the filicalean fern genus Senftenbergia in Pennsylvanian sediments of western North America.
Specimens considered to be compression fossils from putative Pennsylvanian sediments of central Oregon and originally described as Pecopteris oregonensis Arnold have been reexamined revealing that they have anatomically preserved vascular tissues and are assignable to the filicalean family Tedeliaceae. Fern fragments include segments of rhizome with diverging rachides as well as interconnected frond segments that document four orders of pinnately dissected pinnae with lobed pinnules. Individual pinnules display open dichotomous venation with one vein terminating each rounded lobe. Fertile pinnules have large, stalked, solitary sporangia attached at the margin adjacent to a vein ending, and the sporangia are uniformly arranged with their apices oriented toward the center of the pinnule along the abaxial surface. This arrangement of sporangia is more reminiscent of the genus Senftenbergia Corda than Ankyropteris Stenzel or Tedelia Eggert and Taylor, both of which display clusters of abaxial sporangia. The rachis trace is roughly anchor shaped in cross section, with two lateral protoxylem strands and oval primary pinnae traces that diverge in an alternate pattern to form a planar frond. The rhizome displays long internodes, and distinctive dense coarse trichomes are preserved on the rachis and primary pinnae. The overall morphology of this fern conforms closely to that of Ankyropteris brongniartii (Renault) Bertrand (sensu Mickle 1980), and appears to be a liana. This extends the geographic and stratigraphic ranges of Senftenbergia from Europe and Eastern North America to Oregon in western North America, and from the Mississippian to the Pennsylvanian. This species supports the earlier interpretation that Ankyropteris and Senftenbergia are closely related filicalean ferns. Examination of the associated plants in the flora reveals that the only common tree was a species of Calamites Brongniart with Asterophyllites Brongniart foliage and Phyllotheca Brongniart cones. If this association reflects plant interactions then this is the first instance of a fern vine that grew on a calamite tree.
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1 - Ohio University, Department of Environmental and Plant Biology, Athens, OH, 45701, USA
2 - Oregon State University, Department of Botany and Plant Pathology, Corvallis, OR, 97331, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Lindell C/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 9:30 AM