The Mountain Springs Formation is Devonian stratigraphic unit in Arizona. The remains of both antiarch and arthrodire placoderms are known from the formation. Footnotes References Hunt, ReBecca K., Vincent L. Santucci and Jason Kenworthy. 2006. "A preliminary inventory of fossil fish from National Park Service units." in S.G. Lucas, J.A. Spielmann, P.M. Hester, J.P. Kenworthy, and V.L. Santucci (ed.s), Fossils from Federal Lands. New Mexico Museum of Natural History and Science Bulletin 34, pp. 63–69. Geologic formations of Arizona