Abstract Detail


Dunn, Michael [1], Rothwell, Gar [2], Scott, Andrew [3].

Reconstruction of the Whole Plant Tetrastichia bupatides Gordon from the Devonian/Mississippian boundary of Scotland and Ireland.

Tetrastichia bupatides Gordon is a hydrasperman seed fern with a narrow, manoxylic stem that occurs near the Devonian/Mississippian boundary at Oxroad Bay, Scotland and near Ballyheighue, Ireland.  Plant parts are permineralized in volcanoclastic mudflows and appear to have played an early successional role on highly unstable substrates.  Important information about stem structure, stelar architecture, phyllotaxis, and basal frond architecture has been developed by several earlier workers, but an organismal concept for the plant has not been developed previously.  New information to this end includes overall frond architecture and pinnule structure, nature and attachment of pollen organs, identification and position of attachment of cupules, and rooting of the plant.  Seed identity and structure remains uncertain.  The sporophyte has a narrow, unbranched stem up to ~50 cm long, upright growth architecture, a branched taproot, and small adventitious roots diverge near the stem base.  Adventitious prop roots are produced by both stems and proximal to the first fork of the rachis on fronds.  The stem appears to be held upright by both bifurcating fronds and adventitious prop roots.  Internodes generally range 5-42 mm long, but may reach 90 mm or more.  Fronds are planer, fork twice at the base, and then bear alternate-opposite, highly dissected, Rhodea-type pinnules 1.0-1.5 cm long on the tertiary rachides.  Rachael pinnules are not present.  Secondary rachides terminate as an aggregate pollen organ that consists of several closely spaced, equal cruciate forks at the base, and unequal cruciate forks distally.  Ultimate branches terminate as a simple pollen organ that consists of a cushion to which a ring of six elongate microsporangia is attached.  Sporangia are not laterally confluent, and some bear trilete prepollen grains.  A cupule that conforms to Calathospermum fimbriatum Barnard diverges laterally from the rachis at the base of the frond.

1 - Cameron University, Biological Sciences, 2800 Gore Blvd, Lawton, OK, 73505, United States
2 - Oregon State University, Department Of Botany And Plant Pathology, 2082 Cordley Hall, Corvallis, OR, 97331, United States
3 - Royal Holloway, University of London, Department of Earth Sciences, Surrey, TW20 )EX, UK

Hydrasperman seed fern
Devonian/Mississippian boundary
Whole plant reconstruction.

Presentation Type: Oral Paper
Session: PAL3, Paleobotany I: Paleozoic and Mesozoic Paleobotany
Location: Virtual/Virtual
Date: Tuesday, July 28th, 2020
Time: 10:15 AM
Number: PAL3002
Abstract ID:378
Candidate for Awards:None

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