A long snout enchodontid fish (Aulopiformes: Enchodontidae) from the Early Cretaceous deposits at the El Chango quarry, Chiapas, southeastern Mexico: A multi-approach study

摘要

Vegrandichthys coitecus gen. et sp., nov., is described in this manuscript based on a single specimen from the Early Cenomanian marine deposits exposed in the El Chango quarry, Chiapas, Southern Mexico. Although this fish exhibits osteological features to support its insertion as a new member of the family Enchodontidae, it has a peculiar combination of characters that includes the presence of a relatively long and stout snout, lateral exposure of the quadrate and mandible articulation, a series of multiple anteroposterior strengthening bars along the opercle, the lateral line running into a series of complex scales, and the anal fin placed behind the dorsal fin. The phylogenetic position of Vegrandichthys was assessed with multiple approaches, namely Standard Maximum Parsimony (SMP), Implied Weighted Maximum Parsimony (IWMP), Phylogenetic Morphometrics (PM), and Bayesian Inference (IB). The single phylogenetic tree obtained from SMP shows the same topology as that resulting from IWMP: Unicachichthys, Veridagon, and Palaeolycus branch successively at the base of Enchodontidae, with the subfamilies Eurypholinae (comprising Vegrandichthys, Eurypholis, and Saurorhamphus) and Enchodontinae resolved as sister groups. The PM performed, including a landmark configuration of the preopercle, suggests that these data contain true phylogenetic signals. In IB, the phylogenetic hypothesis generated retains the Glade Eurypholinae, but other taxa are located in a very different topology, which is presumably attributed to the data consistency. Vegrandichthys represents the first formally studied long-snout enchodontid from the Americas. It also was found that the stratigraphic fit of Enchodontidae decreases when Enchodus zimapanensis is included in the analysis.