Меловой период

Ovando-Figueroa J.R., Moreno-Bedmar J.A., Chávez-Cabello G. & Minor K.P. (2015) Lower Aptian ammonites of the Sierra de Parras, Coahuila State, northern Mexico // Carnets Géol., Madrid, vol. 15, nº 1, p. 1-11.

http://paleopolis.rediris.es/cg/1501/index.html