Late Pleistocene environments in the southern Zagros of Iran and their implications for human evolution

The Zagros Mountains represent a strategic geographic region near the junction of Africa, Europe, and Asia, and valleys within the mountain range likely correspond to migration corridors used by archaic and modern humans. Ghar-e Boof, a key archeological site in the southern Zagros, is located at an altitude of 905 m.a.s.l. in the Dasht-e Rostam region of the Fars Province, Iran. On the basis of lithic artifacts and radiocarbon and luminescence dating, the Late Pleistocene archeological record of the site spans from the Middle Paleolithic (MP) to the Late Epipaleolithic. Ghar-e Boof includes find horizons of the early Upper Paleolithic (UP) Rostamian dating to 42-35 ka cal. BP. These Rostamian-UP assemblages are typically attributed to modern humans. The high-resolution stratigraphy and microvertebrate record offer a unique opportunity for reconstructing the paleoenvironment of the southern part of the Zagros Mountains during the Late Pleistocene and contribute to a better understanding of long-term hominin settlement dynamics and cultural adaptations in this area. The current paper presents the first analysis of the microvertebrate remains recovered by the Tubingen-Iranian Stone Age Research Project (TISARP) team. All groups of small vertebrates, including fish, amphibians, squamate reptiles, birds, and micromammals, are present in the assemblage from Ghar-e Boof (NISP = 755). The key micromammal taxa used to reconstruct the paleoenvironment during the MP and UP include Libyan jird (Meriones cf. libycus), Vinogradov's jird (Meriones vinogradovi), Indian gerbil (Tatera indica), Brandt's hedgehog (Paraechinus cf. hypomelas), house mouse (Mus musculus), and mole vole (Ellobius sp.). Other taxa, such as amphibians (toad, Bufo/Bufotes sp.), fish (nase, Chondrostoma sp.), and squamate reptiles (agamids, lizards, Eastern Montpelier snake-Malpolon insignitus-and viper), also support the presence of an environment mainly characterized by warm, arid conditions with open, dry meadows, rocky terrain, and water sources close to the site throughout most of the sequence. During the shift from MP to UP, we record Afghan pika (Ochotona cf. rufescens), while all rodents, except very few remains of the Persian vole (Microtus cf. irani) and the Libyan jird (M. cf. lybicus) and some non-hibernating vertebrate species, are absent and reappear in later UP horizons. The presence of pikas could reflect a period of slightly colder and/or drier conditions. While the record from Ghar-e Boof is the only dataset from the southern Zagros, previous studies on microvertebrates from the central and northern Zagros show no clear change during the shift from the MP to the UP. Data from sediment cores and pollen analyses document numerous environmental and climatic fluctuations during the Late Pleistocene of the Zagros. The microvertebrate record from Ghar-e Boof improves our understanding of paleoenvironments during the Late Pleistocene and opens new opportunities to reconstruct the ecological conditions that helped to shape hominin settlement dynamics in the region.