Arundian (carboniferous) conodonts from South Wales and the techniques used in conodont studies

Abstract

A relatively diverse conodont fauna has been recovered from a sample transect through the varied subenvironments of the carbonate ramp which existed to the south of St George's Land during Arundian times. The fauna includes elements referred to the multielement species: Cavusgnathus altus, Clydagnathus gilwernensis, Gnathodus cuneiformis, G. aff. girtyi, G. texanus, G. homopunctatus, G. mermaidus, G. symmutatus, Hindeodus cristulus, ?H. scitulus, Idioprioniodus cf. healdi, Kladognathus aff. levis, Lochreia commutata, Mestognathus beckmanni, Patrognathus capricornis, Polygnathus bischoffi and Vogelgnathus cf. campbelli. Elements recovered which have not yet been referred to multielement species are: Angulodus cf. sp. nov. B of Rhodes et al. (1969), `Apatognathus' cuspidatus, `A.' libratus, `A.' petilus, Geniculatus cf. claviger and Gen. et sp. nov. The outer ramp fauna is the most abundant and is dominated by species of Gnathodus. The cavusgnathoid genera and Polygnathus bischoffi are virtually confined to the more nearshore environments; and Vogelgnathus cf. campbelli and ?Hindeodus scitulus, although recovered from throughout the study area, were capable of living in extreme, euryhaline(?), littoral environments. The Arundian outer ramp deposits have been divided into a series of three biostratigraphical zones on the basis of conodonts (Gnathodus cuneiformis Zone, G. texanus Zone and G. aff. girtyi Zone). This zonation does not correlate directly with any previously erected zonations, but parallels are drawn with the Arundian conodont faunas of the Craven Lowlands (Metcalf 1981) and County Limerick (Austin and Husri 1974). The reported stratigraphical ranges of the following species have been extended: Cavusgnathus altus, Clydagnathus gilwernensis, Gnathodus cuneiformis and Idioprioniodus healdi(?). Gnathodus girtyi is thought to have developed from a previously undescribed gnathodontan - here termed G. aff. girtyi, and it is suggested that the form species Angulodus cf. sp. nov. B and Gen. et sp. nov. existed together in the same apparatus which may have been ancestral to Aethotaxis advena. Conodonts recovered from the Llanelly Formation are stratigraphically long-ranging forms, but are taken to imply a Chadian to mid-Arundian age. The overall changes seen in the conodont fauna through Arundian times do not support the adoption of an event based philosophy of conodont biostratigraphy; but suggest that, in this instance, conodont evolution occurred as a cumulative mosaic of effects rather than as short sharp punctuations in a series of `equilibria'. A review is made of the variety of processing techniques available to conodont workers.bye

More information

Identifiers

Catalogue record

Export record

ASCII CitationAtomBibTeXData Cite XMLDublin CoreDublin CoreEP3 XMLEndNoteHTML CitationHTML CitationHTML ListJSONMETSMODSMPEG-21 DIDLOpenURL ContextObjectOpenURL ContextObject in SpanRDF+N-TriplesRDF+N3RDF+XMLRIOXX2 XMLReferReference ManagerSimple Metadata