FEEDING HABITS AND MOBILITY OF EQUUS CONVERSIDENS AND E. MEXICANUS FROM LA PRESITA BLANCA, SAN LUIS POTOSÍ, MÉXICO

Pleistocene horses were an animal group of which remains have been found in several Mexican localities, such as in La Presita Blanca, San Luis Potosí where bone remains from two equid species were identified: Equus conversidens and Equus mexicanus. In order to infer the feeding habits for those horses we used stable carbon and oxygen isotope ratios from dental enamel. ⁸⁷Sr/⁸⁶Sr analyses of the same material were used to compare with radiogenic strontium ratios of La Presita Blanca plants and soils to identify if those horses were local or came from another location. The δ¹³C value of Equus conversidens was -1.4‰ and -2.0‰ for δ¹⁸O, while carbon and oxygen isotopic values of E. mexicanus were -5.8‰ and -3.9‰, respectively. ⁸⁷Sr/⁸⁶Sr value for Equus mexicanus was 0.705397 and 0.706325 for E. conversidens. Comparisons assayed with ⁸⁷Sr/⁸⁶Sr from La Presita Blanca showed that strontium value for E. conversidens is similar to plant and soils ratios of La Presita Blanca, but the value for E. mexicanus is different. Combined isotopic results indicate that E. conversidens was an animal that fed on C₄ plants and was native to this location whereas E. mexicanus was a mixed feeder and possibly migrated from another site.