Article: A Late Permian actinopterygian fish from Australia
K. S. W. Campbell and Le Duy Phuoc
Ebenaqua, a new genus of deep-bodied palaeoniscoid fishes, type species E. ritchiei sp. nov., is described from the Late Permian Rangal Coal Measures at Blackwater, central Queensland. It is interpreted as an early member of the Bobasatraniformes. Examination of a large number of characters on specimens from the Kupferschiefer suggests that the genus Platysomus is also a bobasatraniform. The homologies of the bones in the suborbital and maxillary regions of members of this order are reinterpreted. A functional study of the jaw mechanics suggests that the forward position of the jaw articulation, the loosely articulated bones of the face, and the markedly upright suspensorium of E. ritchiei are adaptations to a distinctive mode of feeding and gill ventilation. These features should not be used to infer halecostome or neopterygian relationships. The pectoral and pelvic fins are vestigial, and then- functions in the control of manoeuvre and stability are inferred to have been taken over by the dorsal and anal fins, which nevertheless retain a paleoniscoid structure. The versatility of palaeoniscoid fins movements was greater than has been accepted previously.