The oldest Devonian circumpolar ray-finned fish?

Actinopterygians (ray-finned fishes) are the most diverse group of living fishes, but have a sparse early fossil record restricted to low palaeolatitudes. Here we report a new actinopterygian from the Paraná Basin of Brazil, an area that occupied a circumpolar position in the Palaeozoic. Available geological evidence supports a Middle Devonian or older age for this taxon, which shares features of the mandibular symphysis with the latest Devonian Tegeolepis. A phylogenetic analysis resolves these two as sister taxa. This new record expands the palaeogeographic distribution of Devonian ray-fins, and suggests that gaps in the early actinopterygian fossil record might be filled by exploring poorly sampled high-latitude localities within the Malvinokaffric Realm.

Methods
The specimen (Museu de Ciências da Terra, Rio de Janeiro, Brazil, MCT890-P) was scanned with a GE Phoenix v|tome|x m scanner in the Museu de Zoologia da Universidade de São Paulo. We also scanned a dentary of Tegeolepis clarki (Cleveland Museum of Natural History, Cleveland, USA, CMNH 8124) with a Nikon XT H 225 ST scanner in the Department of Earth and Environmental Sciences, University of Michigan.