First acanthodian from the Upper Devonian (Frasnian) Gogo Formation, Western Australia

Abstract

A new acanthodiform acanthodian Halimacanthodes ahlbergi n. gen. n. sp., based on a single uncrushed, partial articulated specimen, represents the first acanthodian collected from the Gogo Formation, Canning Basin, Western Australia. The delicate perichondral ossifications of the lower jaws, branchial skeleton and endoskeletal shoulder girdle are preserved in 3D. H. ahlbergi n. gen. n. sp. is characterised by having a tall slender scapular shaft, paired pelvic fin spines, mineralised branchial arches and scales with an anterior median depression and a microornament of tiny smooth tubercles randomly distributed on the crown. In having paired pelvic spines and lacking prepelvic spines, it is most closely related to Howittacanthus kentoni from Frasnian lacustrine deposits of eastern Victoria. Isolated scales, here attributed to the new taxon, are found in the coeval Gneudna Formation, Carnarvon Basin, Western Australia.

Keywords:

• Devonian
• Acanthodii
• Howittacanthidae
• Gogo Formation
• Frasnian
• Halimacanthodes ahlbergi

Acknowledgements

All the authors acknowledge support of ARC Discovery Grants, in particular DP0772138. CJB thanks the Queensland Museum for provision of basic facilities and use of the Hitachi ESEM; KT acknowledges support of an ARC QEII Fellowship. We thank David Pickering and Tim Holland (Museum Victoria) for assistance with specimen preparation, Mikael Siverson (Western Australian Museum) for access to the collections, and all participants in the 2009 field trip. Helpful comments from reviewers Gavin Hanke and Susan Turner were much appreciated. This is a contribution to IGCP Project 596: climate change and biodiversity patterns in the mid-Paleozoic.