A new genus of fossil coelacanth (Osteichthyes: Coelacanthiformes) from the Middle Devonian of southeastern Australia

WA Museum Records and Supplements | Updated 9 years ago

Abstract: A new primitive coelacanth Gavinia syntrips gen. et sp. nov., is described from the upper Middle Devonian Mt Howitt site, central Victoria. The genus is based on a partial skull, complete caudal fin and distal section of trunk and median fins, some isolated scales, and indeterminate remains. It is regarded as the most primitive member of the Coelacanthiformes because it has a very long dentary bone, approximately 36% of the lower jaw length, a relatively elongate cheek region, and coarsely omamented scales. It retains the basic coelacanthiform synapomorphies of having a tandem double lower jaw joint; broad-headed, short hyomandibular; large, deep operculum; and a rostra I organ denoted by the large pore system in the snout bones. Isolated coelacanth remains from the Pambula River site, New South Wales, are also referred to Gavinia sp. indet. A provisional phylogenetic analysis places Gavinia as the plesiomorphic sister taxon to all other Coelacanthiformes (Actinistia), and this suggests a possible origin for the clade in eastern Gondwana.