 The genus was erected by Ramsay Traquair in 1888 to accommodate certain species that had been previously assigned to Acanthodes by Louis Agassiz.These species included "Mesacanthus mitchelli", "Mesacanthus pusillus", "Mesacanthus peachi" and "Mesacanthus coriaceus".The genus is found in both Lower Old Red Sandstone and Middle Old Red Sandstone assemblages, with "M. pusillus", "M. peachi" and "M. coriaceus" known from the Middle Devonian and "M. mitchelli" being the only known species from the Lower Devonian.