The acanthodian originally described as Euthacanthus curtus Powrie, 1870 from the Early Devonian (Lochkovian) of Scotland was tentatively reassigned to Diplacanthus Agassiz, 1844 later in the nineteenth century, although doubt was cast on this revision. In 1976 Paton suggested that specimens comparable with the single type could belong to Uraniacanthus Miles, 1973, based on similarities with the type species U. spinosus Miles, 1973 from the Lochkovian of England. Hanke et al. (2001) noted that the Canadian Lochkovian species Gladiobranchus probaton Bernacsek & Dineley, 1977 was also very similar to U. spinosus. Our investigations indicate that all three species belong to the genus Uraniacanthus (which has priority over Gladiobranchus Bernacsek & Dineley, 1977) in the family Gladiobranchidae Bernacsek & Dineley, 1977, order Diplacanthiformes Berg, 1940 (revised). This identification supports a biogeographical connection between the Canadian, Scottish and English Early Devonian based on the common presence of the genus Uraniacanthus, as well as other acanthodian genera, including Ischnacanthus Powrie, 1864. Uraniacanthus could also be represented by isolated scales in coeval deposits in the Baltic.
Lochkovian, Acanthodii, Diplacanthiformes, Gladiobranchus, Euthacanthus, biogeography