Taxonomic revision and paleoecology of Middle Devonian (Eifelian) fishes of the Onondaga, Columbus and Delaware limestones of the eastern United States

The Eifelian stage of eastern North America has produced the remains of a substantial number of fish taxa, mostly from the Onondaga Limestone of New York and the Columbus and Delaware limestones of Ohio. Fish specimens in rock matrix from the Buffalo Science Museum and the Cleveland Museum of Natural History were compared to rock samples taken from quarries in Cheektowaga, New York and Warrensburg, Ohio, in order to determine the units from which the fish specimens originally came. This method allowed reasonable inference into the provenance of the museum specimens.;The stratigraphy indicates that the seas of New York and Ohio were deepening throughout the Eifelian, terminating in the dark shale beds of the Givetian stage. The rock units of both areas are characterized by a series of aggradations and inundation events.;Of the 41 taxa of fish originally found in the two museums, only nine are considered valid as a result of this study. Macropetalichthys sullivanti was a benthic dweller found in the deeper units of the upper Moorehouse and Seneca members of the Onondaga Formation and the Delaware Limestone as well as the shallower units of the upper Columbus. M. rapheidolabis is considered a junior synonym of M. sullivanti .;Palaeomylus and Ptyctodus were both durophagous fishes that probably stayed near the bottom of the sea. Ptyctodus was found only in the upper Moorehouse, but Palaeomylus was found in the upper Columbus, Delaware and the upper Moorehouse. Rhynchodus was found in the same units, but was a predator with shearing dentition.;Deinodus bennetti was a common element of the upper Moorehouse and was a ptyctodont. It is likely, based on dental elements in the Buffalo Museum of Science, that D. bennetti was durophagous. Deinodus ohioensis, n. sp., a shallow water fish very similar to D. bennetti is formally described. Little can be theorized about its feeding strategy because most of the dental elements studied were imbedded in matrix.;Onychodus and Machaeracanthus were large, mobile predators that moved in and out of deeper waters, perhaps into shallow waters to feed. Both possess large tooth whorls and elongate jaws. Machaeracanthus is formally placed in the family, Ischnacanthidae, based on these whorls and Machaeracanthus major is considered a junior synonym of M. peracutus