A new species of the crossognathiform fish Nusaviichthys (Teleostei) from the Albian marine limestones of Tlayúa Quarry in Puebla, Mexico

Recently, Mexico has become a significant area for research on Cretaceous Crossognathiformes. Despite this, most Mexican crossognathiforms remain undescribed, and their relationships have not been evaluated within a comprehensive phylogenetic framework. In this study we describe a new species, Nusaviichthys antigonae sp. nov., which exhibits the diagnostic features of the genus, including the mesoparietal condition of the skull and numerous small, conical teeth on the vomer and both jaws. The new species is distinguished from Nusaviichthys nerivelai by the nearly smooth external surfaces of the jaw and dermal skull bones, which lack the conspicuous ornamentation present in the latter species. The discovery of N. antigonae expands the known taxonomic diversity of Crossognathiformes during the Cretaceous and further highlights the importance of the Mexican fossil record for understanding the evolutionary history of this group.Nayeli Lupercio Espericueta* [nayelupercio@comunidad.unam.mx], Posgrado en Ciencias de la Tierra, Instituto de Geología, Universidad Nacional Autónoma de México, Ciudad de México, 04510, México; Jesús Alvarado-Ortega [alvarado@geologia.unam.mx], Instituto de Geología, Universidad Nacional Autónoma de México, Circuito de la Investigación S/N, Ciudad Universitaria, Alcaldía Coyoacán, Ciudad de México 04510, México.