BLANCO-PIÑÓN, Alberto; GARIBAY-ROMERO, Luis M. The oldest stratigraphic record of the Late Cretaceous shark Ptychodus mortoni Agassiz, from Vallecillo, Nuevo León, northeastern Mexico. Revista Mexicana de Ciencias Geológicas, [S. l.], v. 25, n. 2, p. 367–368, 2018. Disponível em: https://rmcg.geociencias.unam.mx/index.php/rmcg/article/view/666. Acesso em: 19 apr. 2025.