Review of Cretaceous Avian Dinosaurs from Mexico: Current Knowledge and Future Perspectives

Abstract

The fossil record of Cretaceous avian dinosaurs in Mexico remains limited compared with that of other vertebrate groups, but provides important evidence on the distribution, taxonomy, and paleoecology of birds in southern North America during the Late Cretaceous. Here, we critically review the currently known Mexican record, integrating osteological remains from Baja California and Coahuila with avian and avian-like ichnofossils from northeastern Mexico. Confirmed skeletal records include the enantiornithine Alexornis antecedens from the Campanian La Bocana Roja Formation and Ichthyornis sp. from the Coniacian–Campanian Austin Group. The ichnological record comprises several Campanian and Maastrichtian occurrences from the Cerro del Pueblo and Las Encinas formations, including the formally recognized ichnotaxon Leptoptilostipus isp. and additional footprint morphotypes. Critical reassessment indicates that footprint morphotypes cannot be equated directly with biological taxa because substrate properties, preservation, locomotor behavior, and other extramorphological factors may influence track morphology. Nevertheless, the combined osteological and ichnological evidence documents the recurrent presence of avian trackmakers across non-marine, marine, deltaic, wetland, and marginal environments in Mexico. The Mexican record therefore provides an important southern North American perspective on Cretaceous avian distribution while also highlighting substantial preservational and sampling biases. Future progress will depend on the renewed study of existing collections, targeted recovery of small vertebrate remains, and systematic reassessment of historically important tracksites.