The paleontological record of vertebrates in the state of Aguascalientes consists mainly of the study of fossil mammals ranging from the Miocene, including carnivores, small mammals and artiodactyls (Dalquest and Mooser, 1974; Montellano and Jimenez-Hidalgo, 2006), to the Pleistocene in the area of El Cedazo including ages from the Late Blancan to the Rancholabrean (Ferrusquía-Villafranca et al., 2010) with the presence of giant armadillos, gliptodons, giant sloths, canids, gray foxes, saber-tooths, lynxes, jaguars, Pleistocene lions, badgers, bears, hedgehogs, gophers, pronghorn, bison, camels, deer, peccaries, opossums, horses, mammoths and mastodons (Barrón-Ortiz et al., 2008; Dalquest, 1974; Dalquest and Mooser, 1980; Ferrusquía-Villafranca et al., 2010; Hibbard and Mooser, 1963; Montellano Ballesteros, 1990; Montellano and Jimenez-Hidalgo, 2006).

 

In the Cedazo area there are also records of fossil turtles including mud turtles (Kinosternon sp.), giant turtles (Hesperotestudo sp.) and desert turtles (Gopherus sp.). The presence of fossil desert turtles in Cedazo is very important because they include the extinct turtles Gopherus auffenbergi and G. pargenis (Mooser, 1972), which together with Gopherus donlaloi (Reynoso and Montellano-Ballesteros, 2004) are the only three species of extinct turtles recorded in Mexico from the Pleistocene, apart from the genus Hesperotestudo.

 

There is controversy around the validity of G. auffenbergi and G. pargensis as extinct species or whether they belong to the species G. berlandieri which is found in the country today (Carbot-Chanona et al., 2020; Reynoso and Montellano-Ballesteros, 2004), although Vlachos (Vlachos, 2018) when reviewing all fossil turtles in North America validates G. auffenbergi but not G. pargensis, suggesting that this material requires examination.

 

In the course of visits made to the Aguascalientes Regional History Museum (MRHA), 52 fossil remains were reviewed belonging to fossil turtles from two families and three genera (Box 1). The ages of the fossils belong to the middle Pleistocene and late Pleistocene with ages between 781,000 and 11,700 before Present (Montellano Ballesteros, 1990; Mooser, 1980, 1972), at the end of the Cenozoic.

 

Of the material identified the most representative findings were the holotype (fossil specimen that gives the name to a new species) of Gopherus auffenbergi, described by Mooser (1972) and which was believed missing (Vlachos, 2018) (Figure 1), as well as other material from desert turtles of the species Gopherus flavomarginatus, Kinosternon integrum and Hesperotestudo (previously Geochelone) identified by Mooser (1980) (Figure 2).

Box 1. Taxonomy of the fossil specimens identified in the paleontological collection of the Aguascalientes Regional History Museum.

 

It is important to signal that in addition to the fossil materials of turtles described by Mooser (1972, 1980), other materials from fossil turtles were found originally from the El Cedazo site, collected by Mooser but never published. For this reason it is important to analyze this material to increase knowledge of the fossil turtles of the Pleistocene in Aguascalientes and Mexico.

The paleontological record of the state of Aguascalientes mainly comprises studies of mammals; however, there was a major study undertaken in 1972 of fossil turtles with the description of two extinct species of desert turtles called Gopherus auffenbergi and G. pargensis.

Despite the controversy around the validity of these two species, the material has not been exhaustively analyzed since the original year of publication, and in recent international publications the material lacks a catalogue number and has been treated as lost by authors from other countries. As a result, finding it in the safekeeping of the Aguascalientes Regional History Museum is an important discovery that will enable analysis, inventory and register of the material, permitting future studies and highlighting the importance of vertebrate paleontology in Aguascalientes.