Westersheimia pramelreuthensis from the Carnian (Upper Triassic) of Lunz, Austria: More evidence for a unitegmic seed coat in early Bennettitales

• Published in: International Journal of Plant Sciences
• Main Author: Pott, Christian
• Format: Article in Journal/Newspaper
• Language: English
• Published: Naturhistoriska riksmuseet, Enheten för paleobiologi 2016
• Subjects: micropylar plate; cupule; integument; seed anatomy; Bennettitales; Pterophyllum; Other Earth and Related Environmental Sciences; Annan geovetenskap och miljövetenskap; Greenland
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:nrm:diva-1890; https://doi.org/10.1086/688708

Premise of research. Isolated ovules and dispersed seeds have been obtained from bulk macerations of carbonaceousshales bearing fossil plants from the Carnian (Upper Triassic) flora of Lunz am See, Austria. Throughcuticle analysis, these well-preserved specimens were identified as ovules, interseminal scales, and seeds of Westersheimiapramelreuthensis, a peculiar bennettitalean ovuliferous organ. The preservation of several cuticularlayers enables for interpretation of the architecture of the ovules and seeds.Methodology. The excellently preserved plant fossils were investigated using LM and epifluorescence microscopyof cuticles. For comparison, the architecture of ovules and seeds of bennettitalean reproductive organsfrom Scania (Sweden), Jameson Land (Greenland), and Yorkshire (United Kingdom) were reevaluated.Pivotal results. The preserved layers indicate that the nucellus is surrounded by an integument, whose apicalend constitutes the micropyle. The single integument constitutes the monolayered seed coat in Westersheimia.The ovules and seeds are surrounded by interseminal scales. Of the latter, the cuticle is preserved that abutsthe ovule-seed surface, together with portions of the interseminal scale heads. The seeds provide additional informationon the cuticles of the nucellus or embryo.Conclusions. Studies of bennettitalean reproductive organs from Scania (Sweden), Jameson Land (Greenland),and Yorkshire (United Kingdom) facilitated reevaluation of the disputed architecture of bennettitalean seeds.The findings clearly indicate that early bennettitalean seeds can be interpreted as unitegmic.