Naslov
Morphology and wall-ultrastructure of Froelichsporites traversei, an enigmatic sporomorph from the Late Triassic in North America

Autori
Viktória Baranyi, Charles H. Wellman, Wolfram M. Kürschner

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Abstract Book / - , 2016, 261-261

Skup
XIV International Palynological Congress

Mjesto i datum
Salvador, Brazil, 23.10.2016. - 28.10.2016

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Froelichsporites, tetrad, TEM, botanical affinity

Sažetak
Froelichsporites traversei (Dunay & Fisher) Litwin, Smoot, Weems is a prominent palynomorph in the Upper Triassic of Northern America which is permanently found in tetrahedral tetrads. The distribution of the taxon seems to be restricted to the Upper Triassic of North America. It is an important biostratigraphic marker in the Norian and a rise in its abundance around 215 Ma is associated with a significant faunal and floral turnover. Its most striking morphological features are the well- developed pores (ulci) and exine thickening around them on the distal side of each grain. Previous works suggested it was produced by spore producing plants e.g. sphenopsids, or Cheirolepidiaceae. Alternatively, it may represent a prepollen, but its botanical affinity is still unclear. We present preliminary results of a detailed morphological analysis (light microscopy and SEM) of newly collected outcrop material from the Chinle Formation at the Petrified Forest National Park (Arizona, USA). TEM analysis was applied to study the wall ultrastructure which may reveal more information on the botanical affinity of this peculiar palynomorph. The ultrastructure analysis revealed that it has a unique, simple wall structure consisting of only two layers. The outer layer is an electron dense layer with homogenous texture, while the inner layer has spongy-granular texture. A layer with lamination was lacking. The simple wall structure might point to an affinity to spore producing plants (possibly ferns, or bryophytes related the Andreaopsida ; a group of mosses). However, the distal pores and the occurrence exclusively as permanent tetrads would suggest an affinity with seed plants. An explanation for the lack of the laminated layer and nexine is that it might represent an immature pollen grain with gnetalean affinity in the early stage of tetrad formation, where the nexine is not developed yet. Alternative solution of the unusual morphological and ultrastructural features is that they represent experimentation with angiosperm related features and functions, which often characterize Bennettitalean plants in the Late Triassic.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

POVEZANOST RADA