Wenlock and Ludlow (Silurian) rugose corals from the type section of the Jack Formation, Broken River Provence, northeast Queensland

Abstract

The Jack Formation forms part of the Silurian Graveyard Creek Group within the Graveyard Creek Subprovince in northeast Queensland. The formation comprises alternating intervals of carbonate and siliciclastic rocks deposited in a shallow-marine setting. It is very fossiliferous at a number of levels, and contains numerous species of conodonts, rugose and tabulate corals, stromatoporoids, trilobites, brachiopods, crinoids, low-spired gastropods, molluscs, other invertebrates, microvertebrates, and algae. Conodont data indicate that the succession is Wenlock to Ludlow in age at the type section along the Broken River in the Jack Hills Gorge area. Fourteen rugose coral species and one subspecies, referable to eleven genera, are described from the type section of the Jack Formation. New taxa described are Aphyllum pachystele sp. nov., Pycnostylus polyphyllodus sp. nov., Multicarinophyllum vepreculatum sp. nov., Dokophyllum hillae sp. nov., Vesicospina julli gen. et sp. nov. and Ptychophyllum variatum sp. nov. The rugose coral fauna shows a high degree of endemism with only four species recorded outside the Broken River Province. Within eastern Australia, it is comparable with a Gorstian to early Ludfordian fauna of the Yass district, New South Wales (3 species in common), and 1–2 species are also shared with coral faunas from other Silurian localities in New South Wales, Victoria and Tasmania. At the species level, there is very little in common with overseas faunas.