A New Early Silurian Species of Trimerella (Brachiopoda: Craniata) from the Orange District, New South Wales

摘要

Trimerella australis, a new species of craniate brachiopod, is described from silicified material extracted from Early Silurian limestone in the Bowan Park district, 22 km west of Orange in central New South Wales. Accompanying conodonts of the Distomodus staurognathoides Zone indicate this unnamed unit is mid Llandovery (latest Aeronian to earliest Telychian) in age, and support correlation'with the Cobblers Creek Limestone at the base of the Waugoola Group. As with most other occurrences of trimerellide brachiopods in the Late Ordovician and Early Silurian of the Lachlan Orogeri, T. australis completely dominates its depauperate faunal associates of corals including Aphyllum? sp., cf. Axolasma sp. and cf. Halysites cratus Etheridge, 1904 , and very rare atrypide brachiopods. Although all specimens of T. australis are disarticulated, the community is interpreted as preserved essentially in situ, representing a very shallow water Benthic Assemblage 2 environment.