Carboniferous fishes | Studies on Carboniferous freshwater fishes. American Museum novitates ; no. 2641

"New material from Nova Scotia, Illinois, and Pennsylvania casts light on certain fish taxa and faunas found in freshwater deposits of the Pennsylvanian and latest Mississippian. The earliest representative of the palaeoniscoid family Haplolepidae is described as Haplolepis (Parahaplolepis) canadensis, a new species distinguished from H. tuberculata by the shape of its frontals and from H. anglica by their tuberculate structure. The presence of H. (P.) canadensis in the early Pennsylvanian (Westphalian A) of Nova Scotia implies a separation of the subgenus Parahaplolepis from the basal haplolepid stock in Mississippian time. The lungfish genus Ctenodus, hitherto extremely rare in North America, is in fact represented by its three European species, each in strata of appropriate age: the primitive C. interruptus in the latest Mississippian (Namurian A) of Nova Scotia, the intermediate C. cristatus in the middle Pennsylvanian (early Westphalian D) of Illinois, and the specialized C. murchisoni in the late Westphalian D of Nova Scotia. Ctenodus, Conchopoma, and Megapleuron constitute a highly anomalous lungfish assemblage in the Mazon Creek deposits of Illinois. Pennsylvanian records of the acanthodian genus Gyracanthus in the Western Hemisphere, previously limited to two specimens, can now be extended by Nova Scotian finds dating from the Namurian A and Westphalian A and B. An unexpectedly late survival of Gyracanthus into Westphalian D time is documented by spines from Illinois; Trichorhipis praecursor is reinterpreted as a prepectoral spine of Gyracanthus. The previously unreported fish fauna of the classic locality at Cannelton, Pennsylvania, comprises the coelacanth Rhabdoderma elegans, the crossopterygian Rhizodopsis cf. robustus, the palaeoniscoids Haplolepis aff. ovoidea and Elonichthys peltigerus and a third genus resembling Commentrya, and the sharks Xenacanthus compressus and Bandringa rayi. The latter genus is shown to be a ctenacanthoid derivable from Goodrichthys, and of freshwater rather than marine habitat"--P. [1].