Circular 135—Some fishes of the Wild Cow Formation (Pennsylvanian), Manzañita Mountains, New Mexico

By J. Zidek, 1975, 22 pp., 4 figs., 2 plates.

First description of fish fauna in Pine Shadow Member shales. Includes specimens of genus Acanthodes, the first described from Pennsylvanian of North America to warrant assignment to this genus. The fish fauna in the shales of the Pine Shadow Member of the Wild Cow Formation in the Manzañita Mountains, NM, has been known for over ten years but has not been described. Although this fauna includes representatives of all the higher taxa of fish known from the Late Paleozoic, few specimens can be identified generically. The Chondrichthyes are represented by the genera Ctenoptychius, Cladodus, and Listracanthus, all apparently extremely scarce. The acanthodian remains are articulated, and although none is complete, their preservation is adequate for a systematic assignment to the genus Acanthodes. These specimens are the first described from the Pennsylvanian of North America in which assignment to Acanthodes is fully warranted. The dipnoans are represented by only a single mandibular tooth plate with the prearticular attached. This dental plate belongs to the genus Proceratodus and is sufficiently different from the described Proceratodus plates that it must be regarded as a new species, herein designated as P. hlavini. The coelacanthiform remains are poorly preserved, consisting mostly of scattered scales, but they are significant because of the presence of a pelvic basal plate showing a coelacanthoid rather than a diplocercidoid affinity. The presence of this plate in the Pine Show Member shales offers evidence that Coelacanthidae existed during Pennsylvanian time, and consequently detached coelacanth scales can no longer be assigned arbitrarily to the Rhabdodermatinae simply because they are found in rocks of Pennsylvanian age.

From 1963 to 1974 D. H. Dunkle, at that time with the U.S. National Museum, collected a large number of fish remains from the Madera Group in the Manzañita Mountains of New Mexico. His collection, from Bernalillo County, was supplemented in 1967 by specimens recovered by S. H. Mamay from the same locality, only about 100 ft west of Dunkle's site. The specimens of both collections are deposited in the U.S. National Museum in Washington, D.C. Dunkle's specimens are preserved in a thinly laminated yellowish-brown argillaceous, limy shale, and most of them are disarticulated. Those added later by Mamay were recovered from a carbonaceous shale and are mostly in good to excellent state of preservation. Most of the fish collected by Mamay belong to the Palaeonisciformes, and will be discussed in a future paper. Because of the fragmentary condition of most of Dunkle's material, only those specimens considered identifiable generically were chosen for discussion, although several less determinable examples are presented to include all the higher taxa present. This study will make possible the resolution of the taxonomy of some of the currently indeterminate remains in the National Museum's collection.