Dietary analysis of Late Cenozoic Mexican equids from three different geographic/geologic settings using stable carbon isotopes: Coincidences, differences and paleobiologic significance

作者：Adrian Perez Crespo Victor; Ferrusquia Villafranca Ismael; Manuel Bravo Cuevas Victor; Morales Puente Pedro; Ruiz Gonzalez Jose E

来源：Journal of South American Earth Sciences, 2016, 66: 97-109.

DOI：10.1016/j.jsames.2015.11.015

• Mexico
• Equids
• Stable isotopes
• Late Cenozoic

The development of Vertebrate Paleontology in Mexico is uneven, so that there is a strong bias in favor of Neogene/Quaternary mammals largely collected in the Trans-Mexican Volcanic Belt (TMVB hereafter) and Central Plateau (CeP hereafter) Morphotectonic Provinces [MP hereafter]; however, the time is ripe for pursuing research in other than taxonomic areas. Here we investigate C-3/C-4 plant consumption in the equid lineage in three such provinces, which provide different geographic/geologic and paleoecologic scenarios during the Barstovian, Hemphillian and Rancholabrean times.
Our results show that the Barstovian equids from Oaxaca, Sierra Madre del Sur MP Cormohipparion aff. C. quinni, Metychippus cf. M. sejunctus and Pliohippus sp. largely fed on C-3 plants, which were the chief food stuff of horses in Mexico, particularly in the Southeast. On the other hand, the Hemphillian equid from Guanajuato, CeP Astrohippus stocki, was an unbalanced C-3/C-4 mixed feeders in favor of C-4 plants, a fact that indicates a profound plant diversification due to the inception and rapid diversification of C-4 plants that occurred there at this time, as it occurred in temperate North America, resulting in the differential consumption of C-4 plants over that of C-3 plants. Such trend prevailed until the Rancholabrean, as born out by the inferred diet for Equus conversidens and Equus sp. from Hidalgo, TMVB.
Clearly then, the coeval diet change observed in Mexico and temperate North America implies a correlative vegetation change resulting in the appearance and rapid diversification of C-4 plants, which largely formed the preferred food stuff of equids since the Hemphillian, although some C-3 plant consumption was maintained till the Rancholabrean. It should be noted that the development of hypsodonty in equids and many artiodactyls, has long been interpreted as the adaptive mammalian response to the new feeding conditions.

• 出版日期2016-3