Rugose corals from the Upper Ordovician Sholeshook Limestone of southwest Wales with an assessment of the coral affinities and biofacies

Abstract

Limestone horizons of Upper Ordovician (Katian) age in southwest Wales contain diverse fossil faunas including rugose corals. The existence of Ordovician Rugosa in Wales was first reported by Murchison in the 1830s, but since then hardly any specimens have been documented systematically until this present study. Newly collected material from the area around Llanddowror (Carmarthenshire) has now confirmed the diversity of rugose corals in the Sholeshook Limestone (Katian age), an arenaceous limestone originating from the shelf edge of the palaeocontinent Avalonia. The majority of the specimens are preserved as moulds. This means that in many instances preservation of the fossils was insufficient for specific identification; nevertheless, it was possible to document a diverse rugose coral fauna, including Helicelasma, probable Grewingkia and Kenophyllum, and a potential early mucophyllid. While associated with considerable difficulties, as some diagnostic features of Rugosa are not visible in moulds, it is demonstrated here that the work with such specimens can result in faunal information which would otherwise be unobtainable. An assemblage of rugose and tabulate corals in the Sholeshook Limestone can be differentiated from a similar assemblage in the neighbouring Robeston Wathen Limestone which has a slightly different lithology. The fauna has strong similarities with other Avalonian (Irish, English, Belgian) as well as Baltic (Estonian and Norwegian) rugose coral faunas. Copyright © 2012 John Wiley & Sons, Ltd.

An association of problematic corals, crinoids and parasites from the Sholeshook Limestone Formation (Ordovician) of Wales

“…1; Fig. The diverse fauna of the Ordovician in Carmarthenshire was listed by Evans (1906); Baars (2013) summarized later detailed studies. The strata are of Cautleyan (Ashgill Series, Zone 2) age of British usage, referable to the Katian Stage of the Upper Ordovician (Ingham and Wright, 1970;Lanc et al, 2013;Ferretti et al, 2014).…”

“…1). Rugose corals from the Sholeshook Limestone Formation were recently described by Baars (2013) who provided a comprehensive review of earlier work. The diverse fauna of the Ordovician in Carmarthenshire was listed by Evans (1906); Baars (2013) summarized later detailed studies.…”

“…The strata are of Cautleyan (Ashgill Series, Zone 2) age of British usage, referable to the Katian Stage of the Upper Ordovician (Ingham and Wright, 1970;Lanc et al, 2013;Ferretti et al, 2014). and a possible mucophyllid were documented from the Talfan Farm locality in a study largely based on silicone rubber casts of calices of the decalcified material exhibiting prominent septation, unlike the currently described specimens (Baars, 2013). Rugose corals from the Sholeshook Limestone Formation were recently described by Baars (2013) who provided a comprehensive review of earlier work.…”

“…Despite their familiar conical morphology, they are not interpreted as rugosans since septa are lacking, although septate Rugosa were described from Talfan by Baars (2013). nov.…”

“…nov. Despite their familiar conical morphology, they are not interpreted as rugosans since septa are lacking, although septate Rugosa were described from Talfan by Baars (2013). Neither is T. calicula readily assigned to one of the other coral or coral-like groups that are known from the Cambrian onwards (Jell, 1984;Scrutton, 1997;Hicks, 2006;Peel, 2011).…”