Brian L. Youngs
Project Topic / Abstract:
"Pollen Morphology and Ultrastructure of
Pramelreuthia, a 230 Million-Year Old Fossil Gymnosperm"
Pramelreuthia is an extinct gymnosperm with a fossil record
placing it in the Upper Triassic (210-230 million years
ago). To date, the plant has only been known from compressed
pollen-producing organs from Austria; however two new
species have recently been discovered in Utah. In the
present investigation, in situ pollen grains from P. duvielii and
P. yazzi have been isolated and critically
studied using light, scanning electron, and transmission
electron microscopy. Pollen grains have been analyzed both
in clusters and individually. The grains are relatively
small, averaging 53 µm in legnth, bisaccate, and have a
single, elongate aperture. The characters examined include
sizes (overall, main body, sacci), wall thicknesses and
infrastucture (proximal, distal, aperture, and sacci), and
internal structure of the sacci. Historically,
Pramelreuthia
has been taxonomically linked to both cycads and seed ferns,
but there is no concensus about its true affinities. It is
hoped that this research will aid in resolving the natural
classification of this fossil.
Presentations:
1999 Truman Undergraduate Research
Symposium (Kirksville, MO)
1999 Sigma Xi Student Research Symposium
(Kirksville, MO)
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