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Abstract Detail

Paleobotanical Section

Dunn, Michael [1], Rothwell, Gar W. [2].

Manoxylic seed ferns from Exposure A at Oxroad Bay (Tournasian) East Lothian, Scotland.

The late Tournasian flora of Oxroad Bay, East Lothian, Scotland has produced a plethora of plant organ fossils that have led to numerous hypotheses regarding the phylogeny of these plants. And these specimens and hypotheses will hopefully lead to the reconstructions of the whole plants that produced these organs. A recent study by the current authors (Dunn and Rothwell, 2012), of specimens from Exposure A at Oxroad Bay, identified 59 stems, plus roots and numerous frond segments of Tetrastichia bupatides. This analysis of more than 8000 cellulose acetate peels, and 500 thin sections identified organic connection of vegetative organs, and arguably most importantly, documented the range of variation (phenotypic plasticity) of numerous characters that had stymied previous attempts to catagorize these plants based on studies restricted to smaller data sets. Once the stems and fronds of Tetrastichia could be segregated from the Exposure A assemblage, the growth architecture of the other two manoxylic seed ferns (Buteoxylon and Triradioxylon) in the assemblage could be recognized. Buteoxylon and Triradioxylon have been lumped together as buteoxylonids, but these new data suggest no sub-spermatopsid relationship. Buteoxylon in known from very few stem tips as well as petioles, but is clearly unlike anything else known to us. These stem tips prolifically produce fronds in a helical phylotaxy with very short internodes. For the several centimeters that the fronds can be tracked, they never exhibit dichotomy, or pinnae production. Triradioxylon stems produce a three lobed protostele, with a well developed periderm and mode of leaf trace production distinctly different than that documented for Tetrastichia

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1 - Cameron University, 2800 Gore Blvd, Lawton, OK, 73505, USA
2 - Oregon State University, Department Of Enviromnental & Plant Biology, 2082 Cordley Hall, Corvallis, OR, 97331, USA

Oxroad Bay
Seed Ferns

Presentation Type: Oral Paper:Papers for Sections
Session: 15
Location: Salon 5/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 2:45 PM
Number: 15006
Abstract ID:366
Candidate for Awards:None

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