1993/01/01 by T.B.H. Jenkins, T. B. H. Jenkins, D.T. Crane +3 · 1 citation
Earth and Planetary Sciences · #Geological Formations and Processes Exploration #Geological and Geochemical Analysis #Paleontology and Stratigraphy of Fossils
paper · doi:10.1080/03115519308619605
openalex publication_date 1993/01/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/29
Conodonts from Visean limestones of the Yarrol and Tamworth Belts of Queensland and New South Wales are, in general, sparsely preserved but widespread and about equally divided between endemic and cosmopolitan species. Patrognathus conjunctus sp. nov. is the commonest conodont in the early Visean and gave rise to Montognathus semicarinatus gen. et sp. nov. and to M. carinatus gen. et sp. nov., the trio being name-bearers for three zones based on endemic elements. The fourth and highest Visean zone has the mondial Gnathodus texanus and Gnathodus bilineatus as joint nominate species, the latter being included in the zonal name to emphasise the restricted definition we adopt for G. texanus. Adetognathus also probably evolved from Patrognathus to give a lineage of three new endemic species: — A. taphrognathoides, A. cannindahensis and A. subunicornis, all predating the earliest adetognathids of the northern continents. Cavusgnathus altifrons sp. nov. is intermediate in platform morphology and time-range between late Tournaisian Clydagnathus and late Mississippian species of Cavusgnathus; Synprioniodina? thompsoni sp. nov., likewise seems to be intermediate between S.? pulchra and Hindeodus cristula. Other new taxa are: Mestognathus convexus, Vogelgnathus angustus, Gnathodus rugulatus and G. girtyi maxwelli. Described and illustrated but left in open nomenclature are Adetognathus? sp. A, Cudotaxis sp. A, Gnathodus sp. A, and Rhachistognathus sp. J. Conodont zones and brachiopod zones give generally accordant divisions, apparent discrepancies being attributable to zonal boundaries locally lacking sufficient data control or being influenced by major facies changes. Approximate limits are indicated in the sequences of eastern Australia for the Lower (VI), Middle (V2) and Upper (V3) divisions of the Visean, account being taken of ages suggested in the recent literature on ammonoids, algae and foraminifera. No evidence is found for any major hiatus in the Visean although regional disconformities mark its base in the Hunter Valley, N.S.W. and its top in parts of the Yarrol-Rockhampton area.