Osteichthyans from an Arkadelphia Formation–Midway Group lag deposit (Late Maastrichtian–Paleocene), Hot Spring County, Arkansas, U.S.A.

A lag deposit that separates the underlying late Maastrichtian Arkadelphia Formation marl from the overlying Paleocene Midway Group limestone in Hot Spring County, Arkansas, U.S.A., contains osteichthyan teeth, scales, and skeletal elements belonging to: Cylindracanthus ornatus Leidy, 1856 Leidy, J. 1856. Description of two ichthyodorulites. Proceedings of the Academy of Natural Science of Philadelphia, 8: 11–12. [Google Scholar], Atractosteus sp., Lepisosteus sp., cf. Hadrodus priscus Leidy, 1857 Leidy, J. 1857. Notices of some remains of extinct fishes. Proceedings of the Academy of Natural Sciences of Philadelphia, 9: 167–168. [Google Scholar], Pseudoegertonia cf. P. granulosus (Arambourg, 1952 Arambourg, C. 1952. Les Vértebrés fossiles des Gisements de Phosphates (Maroc-Algérie-Tunisie). Protectorat de la République Francaise au Maroc. Direction dela Production Industrielle et des Mines, Division des Mines et de la Géologie, Service Géologique, Notes et Mémoires, 92: 1–372. [Google Scholar]), Paralbula casei Estes, 1969 Estes, R. 1969. Studies on fossil phyllodont fishes: interrelationships and evolution in the Phyllodontidae (Albuloidei). Copeia, 1969: 317–331. [Crossref] , [Google Scholar], Enchodus ferox Leidy, 1855 Leidy, J. 1855. Indications of twelve species of fossil fishes. Proceedings of the Academy of Natural Sciences of Philadelphia, 7: 395–397. [Google Scholar], Enchodus gladiolus (Cope, 1872 Cope, E. D. 1872. On the families of fishes of the Cretaceous formations in Kansas. Proceedings of the American Philosophical Society, 12: 327–357. [Google Scholar]), Enchodus petrosus (Cope, 1874 Cope, E. D. 1874. Review of the vertebrata of the Cretaceous period found west of the Mississippi River. U.S. Geological Survey of the Territories Bulletin, 1: 3–48. [Google Scholar]), Enchodus sp., and Teleostei incertae sedis. Outcrop exposures of this lag deposit occur within the Ouachita River and are expressed as a series of partially submerged, steeply inclined fold limbs that strike obliquely to water flow. The co-occurring osteichthyans recovered in this study span a broad range of salinity tolerances, foraging behaviors, and dietary preferences. Concentration of these osteichthyans indicates transport, exhumation, and reburial associated with storm activity or sea level cyclicity across a shallow Late Cretaceous marine shelf. Arkadelphia–Midway osteichthyan taxa belong to groups that survive the Cretaceous–Paleocene extinction event.