LATE DEVONIAN (FAMENNIAN) LUNGFISHES FROM THE CATSKILL FORMATION OF PENNSYLVANIA, USA

Abstract:  Occurrences of fossil lungfishes (Dipnoi: Sarcopterygii) in the Famennian Catskill Formation of Pennsylvania are reviewed. A nearly complete dermal skull roof is assigned to a new genus and species, Apatorhynchus opistheretmus . Other recently discovered lungfish specimens include an incomplete postcranium similar to that of the Frasnian genus Fleurantia , a small parasphenoid of uncertain affinities, and isolated toothplates. Previously described dipnoan remains from the Catskill Formation include a partial skull roof of Soederberghia groenlandica , toothplates assigned to several species of Dipterus , a putative rostral or symphysial region placed in the problematic form taxon Ganorhynchus , and sedimentary structures interpreted as burrows. The toothplates attributed to Dipterus are indeterminate and are placed in open nomenclature, while the specimen identified as Ganorhynchus is not convincingly dipnoan. The status of the burrows remains uncertain pending the discovery of lungfish remains within these or similar structures in Catskill deposits. The distinct ichthyofaunas within the Catskill Formation and their lungfish components are briefly reviewed. Lungfishes are found in the Holoptychius - and Bothriolepis -dominated faunas common in the Catskill succession, as well as in the compositionally distinctive Red Hill assemblage. Many of the Devonian continental faunas that contain tetrapods also include long-snouted, denticle-bearing lungfishes ('rhynchodipterids', fleurantiids, or both). The composition of Late Devonian ichthyofaunas may have predictive qualities that will allow researchers to identify localities likely to produce the remains of early tetrapods.