Mapes, Gene , Stockey, Ruth A. , Hilton, Jason , Rothwell, Gar W. .
Origins of modern conifer families: Jurassic seed cones from Scotland.
Jurassic marine sediments from the North Sea coast of northern Scotland yield calcareous nodules with anatomically preserved plant remains that include conifer wood, leafy shoots, pollen cones, and seed cones. The conifer seed cones are part of the famous Miller collection, and were described as Conites juddi by Seward and Bancroft. Reinvestigation of the seed cone specimens reveals that they display two different morphologies, neither of which clearly conforms to a modern conifer family. These cones range 2.5 - 4 cm in diameter and 3 - 9 cm long, and have distinctly woody axes bearing helically arranged ovuliferous scales with thickened tips. Prominent resin canals occur in the ovuliferous scales, and there appear to be two inverted seeds attached to the adaxial surface of each. Additional preparations of the specimens reveal that three of the cones have no separate bract, and a large resin canal is preserved abaxial to the vascular trace. More distally there are three adaxial resin canals. These three cones also show three small unvascularized vegetative scales distal to ovule attachment on the adaxial surface of each ovuliferous scale. By contrast, the other cone has a distinct bract subtending its ovuliferous scales, and there are numerous resin canals in the cortex of the cone axis both abaxial and adaxial to the scale traces. Ovuliferous scales of this cone show abaxial plications that separate up to nine free lobes at the tip. These cones show novel combinations of characters that do not conform to any of the extant conifer families. However, each has several features that are reminiscent of the Voltziaceae, Araucariaceae, taxodiaceous Cupressaceae, and Pinaceae. A numerical cladistic analysis using morphological characters of ovulate conifer cones provides a preliminary hypothesis for the sister group relationships of these cones, and suggests possible links to living conifer families.
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Seed Plant Phylogeny working group
1 - Ohio University, Department of Environmental & Plant Biology, Porter Hall, Richland Avenue, Athens, Ohio, 45701-2979, USA
2 - University of Alberta, Department of Biological Sciences, Biological Sciences Centre, Cw 405, Edmonton, Alberta, T6G 2E9, Canada
3 - University of Birmingham, School of Geography, Earth and Environmental Sciences, G5 Aston Webb Building, Edgbaston, Birmingham, B152TT, United Kingdom
Presentation Type: Oral Paper:Papers for Sections
Location: Lake Erie/Hilton
Date: Tuesday, July 10th, 2007
Time: 8:45 AM