A revision of the Middle Triassic scanilepiform fish Fukangichthys longidorsalis from Xinjiang, China, with comments on the phylogeny of the Actinopteri

ABSTRACTThe scanilepiform ray-finned fish Fukangichthys longidorsalis, from the Middle Triassic non-marine Kelamayi Formation of Xinjiang, China, was previously described incompletely, with many of its morphological characteristics unnoticed or misidentified. This study provides a revision of this problematic taxon based on an extensive reexamination of the original fossil material. Newly recognized anatomical information includes a plate-like quadratojugal, a triangular dermohyal, a wedge-shaped angular, two infraorbitals, three supraorbitals, fringing fulcra on the pectoral fins, and conical, acrodin-capped teeth in the jaws. Results of a phylogenetic analysis confirmed Fukangichthys as a scanilepiform within the Neopterygii, and provided new insights into the evolution of early actinopteran fishes. Cosmoptychius, previously regarded as the oldest stem-group neopterygian, and Brachydegma, previously hypothesized to be the oldest halecomorph, are here reinterpreted as a stem-group actinopteran and a stem-group neopterygian, respectively. Additionally, Discoserra, previously hypothesized in a position close to the Holostei/Teleostei split, is now recovered in a clade with Ebenaqua, Bobasatrania and Platysomus gibbosus, and is therefore phylogenetically distant from crown neopterygians. As a consequence, fossil candidates for divergence time calibrations within the Actinopteri require reconsideration.SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP