Paramylostoma arcualis is an extinctselenosteidarthrodireplacoderm from the Late FamennianCleveland Shale of Late DevonianOhio. It has a compressed, box-like head and thoracic armor, and large, rounded orbits. However, in comparison with other selenosteids, such as Selenosteus, P. arcualis' orbits were rather small. P. arcualis had smooth jaws that suggest the animal was durophagous.
References
^Denison, Robert (1978). Handbook of Paleoichthyology, Volume 2, Placodermi. New York: Gustav Fischer Verlage. p. 97. ISBN9780895740274.