Acanthodian fish remains from the Lower Devonian Cavan Bluff Limestone (Murrumbidgee Group), Taemas district, New South Wales

Abstract

A well-preserved acanthodian fish fauna from the Lower Devonian (early Emsian) Cavan Bluff Limestone (Murrumbidgee Group), Taemas, Yass district, New South Wales, consists of dentigerous jawbones, fin spines and scales. Four taxa belonging to the Order Ischnacanthida are recognized including Taemasacanthus erroli Long, 1986 and newly described genera and species Cavanacanthus warrooensis gen. et sp. nov., Cambaracanthus goodhopensis gen. et sp. nov. and Taemasacanthus porca sp. nov. An amended diagnosis is provided for T. erroli. The jawbone of C. warrooensis gen. et sp. nov. is of moderate size and bears a single row of teeth with a circular parabasal section. The jawbone extends in an anterior direction beyond the foremost tooth. C. goodhopensis gen. et sp. nov. is a small to moderate sized jawbone bearing two teeth rows separated by a longitudinal ridge. The teeth of the mesial tooth row, the main tooth row, are circular in parabasal section. The lateral tooth row is weakly developed, bearing one or two incipient teeth. T. porca sp. nov. is represented by a small curved jawbone (mesially concave) bearing two teeth rows separated by a prominent longitudinal ridge. The teeth of both tooth rows have a circular parabasal section. The anterior extension of this ridge beyond the foremost tooth represents approximately one quarter the length of the jawbone. These fishes inhabited a Lower Devonian carbonate platform consisting of patch reefs built upon a muddy substrate on a low energy shallow marine shelf which was subjected to frequent storm surges.