A new ptyctodont (placodermi) from the upper devonian martin formation of northern arizona, and an analysis of ptyctodont phylogeny

Ptyctodonts from the Upper Devonian Martin Formation on Mt. Elden, northern Arizona, were hitherto known only from tooth plates ascribed to Ptyctodus bradyi. Recent collections include dental elements of P. bradyi as well as body and skull plates and dental elements of a previously unknown ptyctodont, described here as Denisonodus plutonensis new genus and species. Comparison with other ptyctodonts suggests that the new genus has close affinities to other North American forms. As the holotype of Ptyctodus bradyi has been lost a neotype is designated here.