Rhipidistians (Sarcopterygii) from the Hunter Siltstone (Late Famennian) near Grenfell, NSW, Australia

Abstract

Rhipidistian sarcopterygian fishcs (Dipnornorpha + Tetrapodomorpha) are well represented in the upper levels of the Hunter Siltstone (latest Famennian) near Grenfell, New South Wales (NSW), Australia. Taxa comprise two porolepiforms (known primarily from scales, including the widely distributed Holoptychius), the basal rhipidistian taxon Grenfellicr nzeemrmnoe n. gen. and n. sp. and two tetrapodomorphs (Eusthenodon guvini n. sp. and Yumbira thomsoni n. gen. and n. sp., both known from skull bones and scales). Biogeographic relationships of the Hunter Siltstone fauna are based on the presence of the placoderm group Sinolepidoidei, shared with Late Devonian faunas from the North and South China tcrranes. Rhipidistiaii scales have been described from the latter in association with Late Devonian sinolepids (Sinolepis). but these do not display close taxonomic affinity to scales described from Grenfell. Other Upper Devonian NSW localities show strong faunal similarity to Euramcrican localities; Holoptychius occurs in certain of these and at Grenfell, but has not been recorded from Sh7o-lepis-bearing units on the North and South China terranes. These considerations further contradict suggestions that Asian terranes acted as a dispersal route between Gondwana and Euramerica in the Late Devonian.Key words: Rhipidistians, Australia, Late Devonian, Famennian, Southeast Asia. ZusammenfassungRhipidistiide Sarcopterygier (Dipnomorpha + Tetrapodomorpha) sind in den obersten Schichten des Hunter Siltstone (oberstes Famennium) bei Grenfell, New South Wales (NSW), Australien, stark vertreten. Es handelt sich um zwci Porolepiforme (vertreten hauptsachlich als Schuppen, darunter die weit verbreitete Gattung Holoptychius), der primitive Rhipidistier Gwrfellin meenzunnue n. gen. et n. sp. und zwei Tetrapodomorphe (Eusthenodon guvini 11. sp. und Ynmbirn thomsoni n. gen. el n. sp., beide vertreten durch Schadelknochen und Schuppen). Biogeographische Beziehungen der Hunter Siltstone-Fauna sind auf der Anwesenheit von sinolepidoiden Placodermen, die in oberdevonischen Faunen der nord-und sudchincsischen Tcrranes auftreten, begriindet. Rhipidistier-Schuppen sind zusammen mit oberdevonischen Sinolepiden (Sinolepk) von den chinesischcn Terranes beschrieben worden, aber diese zeigen keine nahe taxonomjsche Ubereinstimmung mit den Schuppcn von Grenfell. Andere oberdevonische Lokalitaten von NSW zeigen deutliche Ahnlichkeiten in der faunistischen Zusammensetzung mit euramerikanischen Lokalitaten; Holotychius tritt dort und in Grenfell auf, aber ist nicht von Schichten in nordund sudchinesischen Terranes, die Sinolepis enthalten, beschrieben worden. Auch diese Vergleiche widersprechen Vorstellungen. dass die asiatischen Terranes im Oberdevon als Verbreitungsweg zwischen Gondwana und Euramerika dienten.

A New Tristichopterid (Sarcopterygii, Tetrapodomorpha) From the Upper Famennian Evieux Formation (Upper Devonian) of Belgium

“…While Langlieria is so far only known in the Upper Famennian of Belgium, Eusthenodon is a cosmopolitan genus that occurs in the Famennian of East Greenland (Jarvik 1952), central Russia (Andreyevka‐2 locality in the Tula Region; Alekseev et al. 1994; Lebedev 1995), Australia (Grenfell, NSW; Young 1993; Johanson and Ritchie 2000; Johanson 2004, and possibly Eden, Worange Point Formation, NSW; Johanson and Ritchie 2000; Ahlberg et al . 2001), South Africa (Witpoort Formation; Gess and Hiller 1995; Anderson et al.…”

A Gigantic Sarcopterygian (Tetrapodomorph Lobe-Finned Fish) from the Upper Devonian of Gondwana (Eden, New South Wales, Australia)

“…Several other elongate elements, expanded at both ends like that illustrated from Grenfell, NSW ([17]: fig. 7), may be fin radials, for example partly exposed inside the right orbital notch of the holotype (?f.r, Figs.…”

“…However, there are differences in shape of the Groenlandaspis bones from the two localities ([9]: fig. 4), and the distinctive porolepiform scales from Grenfell [17] have never been found in the Worange Point Formation, nor the sinolepid antiarch Grenfellaspis , so an age difference within the Famennian seems likely.…”

“…What is clear from currently available evidence is that Eusthenodon sensu stricto (from the East Greenland type locality), and in fact all other Northern Hemisphere tristichopterids, should be scored as lacking accessory vomers. Similarly, the remains from Grenfell, NSW, assigned to Eusthenodon [17], [18] should be treated with caution until more complete remains are found, given that the above description of Edenopteron shows numerous differences in morphology, even if there are close similarities in certain dermal bones.…”

“…In addition, isolated skull and jaw bones from the Grenfell fossil fish assemblage of central NSW (Hunter Siltstone; Famennian), were referred to Eusthenodon [17], [18], another large Northern Hemisphere tristichopterid first described [19] in association with the tetrapods Ichthyostega and Acanthostega from the latest Devonian (Famennian) of East Greenland. Mandageria from Canowindra was first interpreted to be more closely related to Eusthenodon than to the associated Cabonnichthys [11], [16], but alternatively Young [20] noted characters indicating that the two Canowindra genera should belong in their own subfamily, including extra paired dermal bones in the palate (‘accessory vomers’) in both Canowindra genera.…”