Two new acanthodian species are described from the Spitsbergen Old Red Sandstone. Mesacanthus grandis n.sp. is represented by an articulated specimen showing unornamented body scales, elongate modified tectal scales, and a mesacanthid type of scapula. The second species, Xylacanthus minutus n.sp. is represented by a right branch of the mandible in lingual view, showing a single row of triangular striated teeth with an anterior flange. Phylogenetic affinities of these forms are discussed as well as their paleoenvironmental significance.
acanthodian, Devonian, Spitsberg, systematics, Mesacanthus, Xylacanthus