MICROSCOPIC CHONDRICHTHYAN REMAINS FROM PENNSYLVANIAN MARINE ROCKS OF OHIO AND ADJACENT AREAS. (VOLUMES I AND II)

Microscopic teeth and scales of chondrichthyan fishes, derived from acetic acid residues from 106 localities representing 14 marine beds of Pennsylvanian age in Ohio and adjacent areas of the central Appalachian Basin, are referable to 34 species, of which 24 are formally named. Of these formally defined species, 14 are teeth, two of which are new genera and four of which are new species. Ten species are formally defined by dermal denticles; four of these are new genera and three are new species. Ten taxa are informally designated; four of these are teeth and six are dermal denticles. Two forms of mucous membrane denticles are also described.; Teeth include those of a xenacanthid, two ctenacanths, four hybodonts, four symmoriids, a neoselachian, a psammodontid, a species (Venustodus argutus) from an unnamed order, and three informally designated varieties which presently cannot be referred to a higher taxonomic category. Fragments of cochliodont and petalodontid teeth are also among the identifiable chondrichthyan remains. Scales are of the growing and nongrowing (placoid) varieties; several taxa exhibit complex morphological transition series. Owing to low frequency in most samples, mutual-occurrence data are inadequate to positively associate taxa defined by teeth with those defined by dermal denticles. Most dermal denticles cannot, with certainty, be assigned to higher taxonomic categories.; The majority of species in the fauna have stratigraphic ranges which span the entire Pennsylvanian marine sequence in the Appalachian Basin. Ten species in the fauna appear to have limited stratigraphic ranges; however, all but two of them have limited biostratigraphic value because of low frequency of occurrence.; This study is the first attempt to evaluate a microscopic marine chondrichthyan fauna sampled through nearly the entire Pennsylvanian System. It clearly demonstrates that such isolated remains can be divided into biologically meaningful and taxonomically workable species using traditional binominal taxonomic procedures and refutes the hypothesis that artificial taxonomic schemes are necessary in order to evaluate such chondrichthyan fossils. In addition, data from this study, coupled with data from a large collection of macroscopic chondrichthyan remains, provide the first comprehensive census of the marine chondrichthyan fauna from a Pennsylvanian carbonate platform facies.