Owensia chooi: a new tetrapodomorph fish from the Middle Devonian of the South Blue Range, Victoria, Australia

Abstract

A new cosmine-covered, tetrapodomorph fish Owensia chooi gen. et sp. nov. is described, based on a near-complete, uncrushed ethmosphenoid from the Middle Devonian sediments (Kevington Creek Formation) at Owens Creek, South Blue Range, Victoria, Australia. An anteroposteriorly directed basipterygoid process, an optic nerve foramen positioned dorsal to the basipterygoid process, and an oculomotor nerve foramen located posterodorsal to the basipterygoid process are established as autapomorphies. Owensia shares a broad ethmosphenoid shield, a lack of discernible sutures between the bones of the snout and a dorsoventrally shallow skull with cosmine-covered members of the Canowindridae. Owensia also shares the first two of these features and an occluded view of the nostrils from the dorsal surface with Gyroptychius? australis. However, the phylogenetic relationships between these taxa remain unclear. Superficial comparisons between Owensia and the Northern Hemisphere Lamprotolepis are rejected, with the position of the latter within the Tetrapodomorpha being questioned. A benthic niche for Owensia is suggested based on the presence of a dorsoventrally shallow skull.

Key words:

• Owensia
• Tetrapodomorpha
• Devonian
• South Blue Range
• Australia

Acknowledgements

Special thanks are given to John Long and Brian Choo of Museum Victoria, Professor Patricia Vickers-Rich of the School of Geosciences, Monash University, Clayton, Oleg A. Lebedev, of the Palaeontological Institute of the Russian Academy of Sciences and Tim Senden of the Australian National University for his assistance with tomography. Tim Holland is supported by a Monash University Dean's Postgraduate Scholarship.