Resumo

SANCHEZ, Begoña; PRADO, José Luis  e  ALBERDI, María Teresa. Ancient feeding, ecology and extinction of Pleistocene horses from the Pampean Region, Argentina. Ameghiniana [online]. 2006, vol.43, n.2, pp.427-436. ISSN 1851-8044.

To reconstruct the diet and habitat preference of fossil horses, we measured the carbon and oxygen isotope composition of 35 bone and tooth samples of Equus (Amerhippus) neogeus Lund, Hippidion principale (Lund), and Hippidion devillei (Gervais) from 10 different Pleistocene localities in the Pampean region (Argentina). To compare the three species by stratigraphic age, we divided the samples into three groups: lower Pleistocene, middle-late Pleistocene and latest Pleistocene. Samples of Hippidion devillei from the lower Pleistocene were more homogeneous, with δ¹³C values ranging between -11.73 to -9.79‰. These data indicate a diet exclusively dominated by C₃ plants. In contrast, Hippidion principale and Equus (Amerhippus) neogeus from middle-late Pleistocene showed a wide range of feeding adaptations (with a range of δ¹³C values between -12.05 to -8.08 ‰ in Hippidion and δ ¹³C values between -11.46 to -7.21 ‰ in Equus (Amerhippus)). These data seem to indicate a mixed C₃ - C₄ diet, while data from the latest Pleistocene suggest a tendency toward an exclusively C₃ diet for both species. Furthermore, the results of δ¹⁸O indicate an increase of approximately 4°C from the early to latest Pleistocene in this area. Several nutritional hypotheses explaining latest Pleistocene extinctions are based on the assumption that extinct taxa had specialized diets. The resource partitioning preference of these species from latest Pleistocene in the Pampean region supports these hypotheses.

Palavras-chave : Equus (Amerhippus); Hippidion; Paleodiet; Ecology; Extinction; Pleistocene; Papean region; South America.