Abstract

A new genus and species of an Early Devonian (Emsian) mesacanthid acanthodiform from outcrops of the Bear Rock Formation along the Anderson River, Northwest Territories, Canada, is described. The new taxon is distinct from other mesacanthid genera and (or) species in having mesiolaterally expanded skull roof plates and paired nasal bones. Mesacanthids have fin-spines that are similar in size, number, position, and proportions. This new genus is the fourth in the family Mesacanthidae. The wider distribution and apparent taxonomic diversity represented by the discovery of the new genus are indications that the latest-surviving and arguably most advanced acanthodian group, the Acanthodiformes, was already well established in the Early Devonian.

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