The distribution of plant fossils and their palaeoecology inDuckmantian(Bashkirian, Lower Pennsylvanian) strata atBrymbo, North Wales, UK

Abstract

Plant fossils are recorded and described from Duckmantian clastic strata associated with coal seams in a small conserved area at Brymbo in the Wrexham (North Wales) coalfield. The exceptionally preserved flora consists of adpressions in mudstones, shales, and sandstones, more three‐dimensionally preserved plant remains in ironstone nodules, and three‐dimensionally preserved stems in their original positions of growth. The relationships of the plant fossils to the sediments are discussed and related to the varying conditions affecting the ecology of the area. Sometimes the influx of sediments was very rapid as can be seen by the numbers of erect and branching Calamites, arborescent lycophyte stems, and stigmarian bases preserved in sandstone in their original positions of growth.

Better together: Joint consideration of anatomy and morphology illuminates the architecture and life history of the Carboniferous arborescent lycopsid Paralycopodites

“…We require the leaves of our Paralycopodites to remain attached on all branch and trunk specimens throughout the life of the tree. In light of these observations, we retain considerable sympathy with the concerns expressed by Thomas et al (2019); a greater range of characters should be invoked if a truly useful Bergeria concept is to be circumscribed. There likely is more than one natural species encompassed by Paralycopodites brevifolius, based on its association in coal-ball preservation with at least two distinct kinds of Flemingites cones: F. schopfii (Brack) Brack-Hanes & Thomas and F. diversus (Felix) Brack-Hanes & Thomas (DiMichele, 1980;Bateman et al, 1992).…”

“…The broad scope of this generic diagnosis was soon criticized by Thomas et al (2019), who argued that the presence of leaves in attachment to arborescent lycopsid shoots is an overly encompassing "diagnostic" characteristic. We agree, especially given that the Bergeria concept allows for leaf-cushion shape to vary from vertically elongate to near-equidimensional.…”

“…We agree, especially given that the Bergeria concept allows for leaf-cushion shape to vary from vertically elongate to near-equidimensional. Thomas et al (2019) also asserted that the majority of lycopsid trees likely did not begin to shed their leaves until the crown was produced, and that leaves likely are attached cryptically to many different kinds of fossilized lycopsid stems. The apparent absence of leaves in that scenario is therefore a taphonomic happenstance; the leaves are removed when a compression fossil is split, thus revealing an apparently leafless stem surface in the part, whereas the leaves are actually carried away in the counterpart.…”

Escaping the voluntary constraints of “tyre‐track” taxonomy

“…As discussed by DiMichele & Bateman (2020) and Thomas & al. (2020), Paralycopodites is paralleled in part by a far broader adpression genus Bergeria , established by Presl in Sternberg (1838) but only recently resurrected in a more modern taxonomic context by Álvarez‐Vázquez and colleagues (Álvarez‐Vázquez & Wagner, 2014; Álvarez‐Vázquez & al., 2018). Thomas & al.…”

Why Lycospora dominated many Pennsylvanian spore assemblages

“…This calculation involving reductions in diameter would result in approximately 1,000 terminal branches on a mature tree. Studies of the plant assemblages at Brymbo, North Wales (Thomas et al 2020) revealed that the number of small leafy shoots bearing terminal cones (Text-fig. 3) is less than the number of similar sized shoots not bearing terminal cones.…”