Discovery of a Pleistocene megafaunal assemblage in a cave in Sierra de El Abra, San Luis Potosí, Mexico

The Calera cave system in San Luis Potosí, Mexico, with a large Pleistocene megafaunal assemblage is described. Hundreds of fossil bones have been found throughout the 1324 m of mapped galleries. The fossils are well preserved resulting from partial permineralization by manganese oxide. A preliminary taxonomic identification of the recovered specimens indicates Equus sp. is the most abundant taxon. Other groups include mammoths, gomphotheres, cervids, bovids, camelids, sloths, glyptodonts, felids, canids, lagomorphs, and testudines. It has been estimated that the cave would have started to form between 1.17 and 0.29 Ma. Since the fossils are found on top of or form part of the fluvial sedimentary deposits inside the cave passages, fossil deposition is much younger and probably occurred during the latest stage of cave formation and the fauna represents a time-averaged accumulation. A few specimens are covered with secondary calcite incrustations. The locality described in this study stands out because it contains one of the largest Pleistocene megafaunal assemblages of the region.