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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 positio...

The tetrapodomorph fish Spodichthys buetleri from the Upper Devonian of East Greenland is redescribed from computed tomography scans of material originally studied by Erik Jarvik. A wealth of new a ...

A new tristichopterid, Cabonnichthys burnsi gen. et sp. nov. from the Upper Devonian Mandagery Sandstone near Canowindra, New South Wales, Australia, is the second tristichopterid to be described from this locality. The first, Mandageria fairfaxi, was interpreted as the sister group of the Laurussian taxon Eusthenodon. Cabonnichthys burnsi gen. et sp. nov. is similar to these two taxa in possessing a posterior supraorbital extending ventrally behind the orbit to exclude the postorbital from the orbital margin, a posteriorly positioned pineal surrounded by kite or teardrop shaped bones, and an enlarged fang-like tooth at the anterior end of the premaxillary tooth row. Cabonnichthys burnsi differs from Mandageria and Eusthenodon in retaining a contact between the intertemporal and posterior supraorbital, and in possessing “horn-like” processes on the postparietal shield that notch into the posterior margin of the postorbital. The Tristichopteridae is a clade characterized inter alia by the possessi...

Tristichopterids (Sarcopterygii, Tetrapodomorpha) form a monophyletic group of exclusively Devonian fishes. This thesis consists of descriptions of new material of tristichopterids and closely related taxa, as well as new interpretations and descriptions of previously figured material. Redescribed specimens were originally figured as far back as 1861, and publications as old as this are almost always of limited use as anatomical and systematical references, in addition to being difficult to acquire. The possibility of using new techniques and new theoretical frameworks also provides good justification for taking a second look at such specimens. In the case of this thesis, this includes the use of computed tomography scanning methods, and the cladistic approach to describing the interrelationships of taxa. The thesis includes a complete taxonomy of valid tristichopterid taxa, in addition to two new phylogenetic analyses incorporating the taxa that were described or redescribed. One of the analyses deals with the interrelationships of taxa along the entire tetrapod stem, and establishes the monophyly of the Tristichopteridae. The other analysis focuses on tristichopterid interrelationships. An account is given of evolutionary trends within Tristichopteridae, and instances of parallel evolution between tristichopterids and other tetrapodomorph groups are discussed. The biogeographical implications of tristichopterid occurences world-wide seem to corroborate the picture provided by other vertebrate groups, and give further support to one of two main hypotheses concerning the relative positions of Gondwana and Laurussia, the two major palaeocontinents during the Late Devonian. The supported hypothesis proposes a close proximity between southern Laurussia and northwestern Gondwana, as evidenced by the wide dispersal of derived tristichopterids by the Late Devonian. A Laurussian origin of tristichopterids is proposed.

A new osteolepiform, Marsdenichthys longioccipitus gen. et sp. nov., is described from the Frasnian lacustrine shales (Avon River Group) near Mt Howitt, central Victoria. Because it has thin cycloidal scales with large overlap areas and lacks cosmine in the dermal skeleton Marsdenichthys gen. nov. is regarded as the sister taxon to eusthenopterids. In possessing an extratemporal bone in the skull roof, Marsdenichthys gen. nov. is more primitive than other eusthenopterids. The Osteolepiformes are assumed to be monophyletic by possession of a unique complex of cheek bones, large dermal anocleithrum, scapulocoracoid structure and basal scutes on the fins. Other characters unique to Eusthenopteron such as a long basihyal, fused first infra- and suprapharyngobranchials and large vestibular fontanelles on the braincase may be useful synapomorphies of the Osteolepiformes when more is known of the anatomy of other genera. Problems in defining osteolepidids and eusthenopterids are discussed.

Barameda decipiens, gen. nov. (Woodward, 1906) is described from the Early Carboniferous Mansfield Group, Victoria, Australia. It differs from other rhizodontiforms (Strepsodus, Rhizodus, Screbinodus, Sauripterus) by the shape of the skull roofing bones, course of the supratemporal sensory line, vertebral structure, and pectoral fin skeleton. The skull roof of Barameda, gen. nov., differs from that of Osteolepiformes in having a larger extratemporal bone that contacts the intertemporal, by the overlap areas on the intertemporal, and in having fewer snout bones. The cheek has a very large postorbital bone, and the lacrimai is narrow. There are two external nostrils, which are situated close together and differ in their position in the only other rhizodontiform for which they are known, suggesting that the group was not choanate. Rhizodontiforms are a monophyletic group characterized by specializations of the pectoral girdle and fin. They may be placed in Schultze's (1987) scheme of osteichthyan in...