The axial postcranial structure of Griphognathus whitei from the Upper Devonian Gogo Formation of Western Australia: comparisons with other Devonian Dipnoans

WA Museum Records and Supplements | Updated 6 years ago

ABSTRACT – The skeleton of the pectoral and pelvic girdles, the foremost axial region, and the scales of Griphognathus whitei, and the pectoral and pelvic girdles and scales of Chirodipterus australis, have been described previously. The posterior parts of the postcranial skeleton of these fishes have been commented on in passing, but new material permits a description of the centra, the neural and haemal arches and the incomplete medial fins of G. whitei. The limb skeletons have not been preserved in our material. The new material of G. whitei adds considerably to the information available on the axial skeleton and the medial fins of Devonian dipnoans. Of these dipnoans, only Dipterus has the axial skeleton without the centra well preserved, though fragments of the centra of some of the other genera are poorly preserved. The new specimens of G. whitei have well preserved centra along the full length of the body of the animal. The neural and haemal arches give the best information available on Devonian species. The medial fins are sufficiently well preserved to compare with those of Fleurantia and Scaumenacia from the Upper Devonian of Canada, and the Australian Barwickia and Howidipterus from the Givetian of Victoria. Gross differences occur between all the above genera in the structure of the medial fins. The function of the fins and the centra are discussed, and an attempt is made to show how the whole structure of the movement of G. whitei is related to the bottom dwelling environment in which the animals lived.