Меловой период

Barragán R., Moreno-Bedmar J.A. & González-Arreola C. (2016) Aptian ammonites from Mazapil, Zacatecas State (north-central Mexico) studied by Burckhardt in 1906: A revision // Carnets Geol., Madrid, vol. 16, no. 14, p. 355-367.

http://paleopolis.rediris.es/cg/1614/index.html