Abstract Detail



Paleobotany

Hodges, Nicholas [1], Atkinson, Brian [2], Serbet, Rudolph [3], Taylor, Edith L. [2].

Exploring anatomical variation of Pteruchus (Corystospermales) from the Triassic of Antarctica.

The Fremouw Formation of the central Transantarctic Mountains, Antarctica contains a Middle Triassic permineralized peat flora that has provided crucial data for deciphering Mesozoic plant diversity and evolution. For instance, the first described permineralized corystosperm pollen organ, Pteruchus fremouwensis, was reported from this flora and has clarified homologies. In this study, we characterize a new permineralized morphotype of Pteruchus. There are 36 specimens consisting of a central axis with helically arranged microsporophylls with distinct stalks and slightly flattened laminar heads. Several vascular bundles form a ring within the main axis. Ground tissue of the primary axis contains two layers: an outer zone of sclerenchymatous cells that is several cells thick and an inner zone of parenchymatous cells. A small number of secretory cavities with epithelial linings are scattered within the two tissue zones. A single bundle enters the microsporophyll stalk and subsequently divides prior to entering the microsporphyll head. Ground tissue of the stalk is similar to that of the central axis. The laminar head also consists of two distinct layers. The adaxial layer is heavely sclerified and often coalified. The abaxial layer is made up of thinner walled parenchymatous cells. There are scattered secretory cavities with epithelial linings throughout the microsporphyll head. At least 20 pollen sacs are attached to the abaxial surface of each laminar head. Pollen sac walls are uniseriate at maturity and lack secretory cavities. Several pollen sacs contain in situ bi-saccate pollen grains similar to the Alisporites-type. Comparative analysis indicates that this new Pteruchus morphotype is distinct from P. fremouwensis. Thus, the corystosperm described in this study represents a new taxon. The structure of this new taxon supports the hypothesis that the pollen bearing organs of Pteruchus are homologous to leaves. This study sheds light onto the diversity of corystosperm reproductive structures within the Triassic Fremouw flora. Characterization of this new taxon increases the known range of anatomical variation in Pteruchus and corystosperms as a whole.


1 - University of Kansas, Biology, 1200 Sunnyside Drive, Haworth Hall, Lawrence, Kansas, 66045, United States
2 - University of Kansas, Ecology and Evolutionary Biology and Biodiversity Institute, 1200 Sunnyside Drive, Haworth Hall, Lawrence, Kansas, 66045, United States
3 - University Of Kansas, Division Of Paleobotany, Biodiversity Institute, 1200 Sunnyside Avenue, Lawrence, KS, 66045, United States

Keywords:
Pteruchus
anatomy
Corystosperm
Triassic
Antarctica.

Presentation Type: Oral Paper
Number:
Abstract ID:462
Candidate for Awards:None


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