Taxonomic diversity and environmental inferences through rodent assemblages from the Middle Pleistocene site of Galería (Sierra de Atapuerca, Burgos, Spain)

This work addresses the study of rodents found in the GIIb and GIIIa Subunits of Galería site. This Middle Pleistocene site is of great importance for the understanding of the evolution of hominins in the Iberian Peninsula. The analysis conducted on the fossil micromammals from these subunits provides information about the environment of the Sierra de Atapuerca during the Middle Pleistocene, as well as the species that inhabited the area and their biochronology. The assemblage obtained from GIIb and GIIIa consists of 659 rodent molar remains, belonging to 219 individuals from eight different species: Arvicola cf. sapidus, Microtus ex gr. agrestis, Microtus cf. arvalis, Microtus atapuerquensis, Microtus brecciensis, Pliomys coronensis, Cricetulus bursae, and Marmota sp. All these species belong to the Atapuerca Faunal Unit 6 (ATA FU6) of the Middle Pleistocene. The calculated diversity indices for the rodent assemblages reveal a high species evenness and diversity, with a moderate dominance by the extinct vole Microtus atapuerquensis. The paleoenvironmental and palaeoclimatic approach suggests that the environment during the formation of GIIb and GIIIa subunits was probably an open grassland landscape with a Mediterranean climate, being slightly more humid during the formation of subunit GIIb.