Australia: The Land Where Time Began

A biography of the Australian continent 

Australian Fish of the Permian-Carboniferous

The Carboniferous fish in Australia were dominated by palaeoniscoids, specimens of which have been found in Victoria and Queensland.

Mansfieldiscus sweeti is an example from the Mansfield Group of  Victoria. About 25-30 cm long, it was a fusiform fish with the long gape and heavy scalation typical of the palaeoniscoids, appearing very different from modern ray-finned fish.

Also from the Mansfield Group rocks is a rare crossopterygian Baromedia decipiens. It appears to not be a choanate, as it had no internal nostrils. It is thought to be closely related to a crossopterygian from the Middle to Late Devonian of Antarctica, which is the oldest known fish of its type in the world.

A partially articulated shark, Stethacanthus, was found in a nodule, from the Early Carboniferous Utting Calcarenite of Western Australia. This specimen shows the association of jaw cartilages, scales and teeth, providing a basis for interpreting other isolated bones, teeth and scales.

Microfossils of Permian fish are not common, some being found in the Newcastle Coal Measures of NSW and other units such as the Blackwater Shale of Queensland, where there are forms such as the deep-bodied palaeoniscoid Ebenaqua.

Microfossils from this time allow some insight into the diversity of fish in the waterways, and around the Australian Peninsula of Pangaea. As well as the palaeoniscoids, there were acanthodians, crossopterygians, lungfish and sharks, including teeth of the freshwater xenacanths that have been found in the rocks of the Mansfield Group and the Narrien Range in Queensland.

A variety of sharks have been found in marine rocks from New South Wales and Western Australia. Some scales and teeth from a Late Carboniferous site near Murgon, Queensland, show strong similarities with neoselachians (modern sharks), the advanced sharks sharing their habitat with the primitive ray-finned palaeoniscoids.

Sources & Further reading

Patricia Vickers-Rich, Thomas Hewitt Rich, Wildlife of Gondwana, Reed Australia, 1993