FIGURE 1. Map of Mexico with approximate locations for reported records of Lower Kimmeridgian ataxioceratin ammonites mentioned in text, with reference to Mexican states. Light brown (Oaxaca state). Black star (town of Tlaxiaco at the surroundings of which Schneidia lopeztichai [Cantú-Chapa] was found). Red dots (north-to-south surface records reported and illustrated by López-Caballero, 2009 from Coahuila; Villaseñor, 1991 and Villaseñor et al., 2000, 2015 from Zacatecas; Cantú-Chapa, 1984 and Jiménez-López, 2011 from San Luis Potosí; and Cantú-Chapa, 1991 from Oaxaca). Green triangle (subsurface record reported and illustrated from Veracruz by Cantú-Chapa, 2001). Purple square (subsurface records reported without illustration by Cantú-Chapa, 1969, 1971).