Megaspores from the Late Triassic‒Early Jurassic of southern Scandinavia: taxonomic and biostratigraphic implications

Here we investigate megaspores from 10 Triassic‒Jurassic localities of southern Sweden and Bornholm, Denmark, based on collections housed in the Swedish Museum Natural History. We identify describe 19 megaspore taxa belonging to three stratigraphically constrained assemblages, representing Rhaetian, Hettangian Pliensbachian, respectively. Megaspores are abundant diverse (12 taxa) Rhaetian assemblage. Diversity markedly decreases across Triassic–Jurassic boundary (TJB), with species richness reducing 12 two taxa. The assemblage is well-preserved but depauperate, overwhelmingly dominated by Nathorstisporites hopliticus. A subsequent recovery lycopsid diversity followed, recorded an increase six Pliensbachian disappearance hygrophilous heterosporous lycophyte communities TJB, suggests a shift drier conditions earliest Jurassic. This supported lithological changes coal-forming environments sandstone-dominated fluvial-estuarine facies Hettangian. Throughout this study, analysed using fluorescence microscopy, which revealed detailed morphological features specimens that were otherwise opaque under visible light. non-destructive technique particularly useful for examining embedded permanent mounting media, such as epoxy resin, may provide new insights into historical elsewhere.