Llandovery Brachiopods From England and Wales

Diverse Early Silurian (Llandovery) rocks with shelly benthic faunas have been known for nearly 200 years from Wales and the Welsh Borderland of England, and this monograph revises the Llandovery (Rhuddanian, Aeronian and Telychian) brachiopods from those areas. They are the dominant fossils at most localities in the shelf rocks encircling the deeper-water Welsh Basin. Much of the Aeronian and Telychian fauna has not been revised for over a century, but the Early Llandovery (Rhuddanian) brachiopods are better-known and are thus only summarised here. Only Aeronian and Telychian rocks occur in the Welsh Borderland: the Pentamerus Beds and Hughley Shale Formation in Ape Dale, and other formations encircling the Longmynd-Shelve Inlier, all in Shropshire; and more in the central and southern Welsh Borderland in Worcestershire, Herefordshire and Gloucestershire. Most of those Welsh Borderland formations are unconformable upon rocks of Ordovician and older ages (the western sectors of the Midlands Microcraton), which all then formed part of Avalonia. The latter was a sector of the Baltica-Avalonia continent which had become united just before Ordovician–Silurian boundary time. In contrast, the Llandovery rocks in Wales, which include the type Llandovery area, as well as others in Pembrokeshire, Carmarthenshire and Powys, include those of Rhuddanian as well as Aeronian and Telychian ages. Many brachiopod species originally described in the nineteenth century are revised with updated generic attributions, and some are photographed for the first time. The total number of species and subspecies recognised is 154, of which 29 are in open nomenclature. Sixty-eight pre-existing names are synonymised. New taxonomic work includes the elevation of the Family Leptocoeliidae Boucot & Gill, 1956 Boucot, A. J. & Gill, E. D. 1956. Australocoelia, a new Lower Devonian brachiopod from South Africa, South America and Australia. Journal of Paleontology, 30, 1173–8, pl. 126.[Web of Science ®] , [Google Scholar], to the new Superfamily Leptocoelioidea within the Order Rhynchonellida, with the new subgenus Platytrochalos (Salopicoelia) within it; the new genus Shelvothyris within the Meristelloidea, and 19 new species across the brachiopod spectrum. The associations within which the brachiopods occurred are identified and discussed, including revision of the concepts of the Lingula (now Mergliella), Eocoelia, Pentamerus, Stricklandia and ‘Clorinda’ communities, which were originally defined from collections in this area. The new shallower-water Palaeoleptostrophia–Mendacella Association (BA 2) is recognised and named: it is prevalent in the Early Aeronian Bog Quartzite Formation of Shropshire. Some species of the rhynchonelloid Platytrochalos are external homoeomorphs of Eocoelia, as well as being within the same family Leptocoeliidae; and the new subgenus Platytrochalos (Salopicoelia), is erected to differentiate between the two: both genera occupy closely comparable Benthic Assemblage 2 positions in the shallower-shelf associations which they often dominate.