The Cenomanian short snout enchodontid fishes (Aulopifomes, Enchodontidae) from Sierra Madre Formation, Chiapas, southeastern Mexico

In this paper the short snout Cenomanian enchodontids from the El Chango quarry, Chiapas, southeastern Mexico, are reviewed. Unicachichthys multidentata nov. gen. and sp. is named and identified as a new member of the Enchodontidae because it has the predorsal scute series that is the distinctive character of such family. This new genus resembles other short snout enchodontids, as Enchodus and Eurypholis; however, Unicachichthys differs from these and other members of the family because it shows characters ever observed, including a multitoothed dermopalatine, the presence of a basal sclerotic bone, and the serrations in the posterior edge of the preopercle vertical limb. The inclusion of Unicachichthys in two phylogenetic analyses, based on studies previously performed, suggests that this is a primitive representative of the family Enchodontidae. Additionally specimens of two different species of Enchodus from the El Chango quarry are also described; these specimens are so scarce and fragmentary that it is not possible to determine their specific taxonomic identity. The record of these Mexican fossils enrich the knowledge about the diversity of Cenomanian enchodontids in the North American domain of the Tethys Sea, which now contains new taxa that should be considered in future efforts to recognize the phylogenetic and biogeographic processes experienced by this fish group.