A rare late Mississippian flora from Northwestern Europe (Maine-et-Loire Coalfield, Pays de la Loire, France)

Abstract

Numerous localities in the Maine-et-Loire coalfield in northwestern France have yielded diverse adpression floras belonging to the Calymmotheca stangeri Zone, indicating an early Namurian (Serpukhovian–late Mississippian) age. The floristic affinities are with the South European Palaeoprovince, although there is some evidence of an ecotonal relationship with the Central European Palaeoprovince to the north. The geological context of the deposits suggest that the floras may represent vegetation from an intra-montane setting, although at lower elevations compared with the Pennsylvanian-age Variscan intra-montane basins. This represents some of the earliest known examples of coal swamp vegetation, although compared with the Pennsylvanian-aged coal swamps there was a significantly higher proportion of lycopsid species and a lower proportion of medullosaleans. Most of the Maine-et-Loire fossiliferous localities yielded diverse assemblages of lycopsids, equisetopsids, ferns and Calymmotheca species, and these were used to develop a pictorial reconstruction of this early coal swamp vegetation. However, two of the localities yielded adpressions and associated palynofloras with a greater predominance of lycopsids and sphenopsids, suggesting vegetation of wetter habitats. Two other localities yielded species of a more Pennsylvanian aspect such as Cardioneuropteris and Karinopteris, which may represent drier substrate vegetation.