The Archaeopterid Forests of Lower Frasnian (Upper Devonian) Westernmost Laurentia: Biota and Depositional Environment of the Maywood Formation in Northern Wyoming as Reflected by Palynoflora, Macroflora, Fauna, and Sedimentology

Premise of research. The flora the Maywood Formation, one only three Devonian floras previously recognized in western North America, is known from a brief report focused on stratigraphy and has never been characterized more detail. A detailed assessment this associated animal fossils implications for age depositional environments Formation plant biogeography.Methodology. Fieldwork at Cottonwood Canyon (Wyoming) exposure produced measured section characterizing sedimentology unit samples that we analyzed palynomorph, macrofloral, faunal content using standard methods.Pivotal results. palynological assemblage dominated by archaeopterid progymnosperm spores, lacks unequivocally marine components, indicates low burial depth temperature (ca. 53°C) unit, supports an early Frasnian age. Plant macro- mesofossils including charcoal, adpressions, sporangia, spore packages reflect vegetation with quasi-monodominant archaeopterids but also (unidentified) plants seed megaspore Spermasporites (for which occurrence represents geographic range extension). Scales indicate presence sarcopterygian tetrapodomorph fishes. Sedimentary facies, palynofacies, macrofossil taphonomy are consistent lagoon or lake margin environment carbonate platform disconnected open realm.Conclusions. arid Laurentia hosted fire-prone cover heavily progymnosperms. preserves fossil assemblages reflecting (Wyoming), lagoonal lacustrine deposits host microconchid tube worms fish. parent Spermasporites, present vegetation, was widely distributed all across Euramerica.