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

Abstract

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 Tübingen-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.

Evidence of diverse animal exploitation during the Middle Paleolithic at Ghar-e Boof (southern Zagros)

“…Although the faunal assemblage is primarily dominated by ungulates (NISP = 710), we also present the skeletal element representation and anthropogenic modifications of carnivores (NISP = 7), tortoises (NISP = 161), and medium and large bird (NISP = 63) remains in order to assess the complete animal foraging spectrum of MP hominins at the site, beyond just ungulate/large game hunting. Our sample does not include small mammals (rodents, pikas, and insectivores), amphibians, squamate reptiles (agamid lizards and snakes) and small birds (Passeriformes), since the accumulation of these taxa at the site was most likely the result of non-hominin predator activities or natural death 61 .…”

“…However, the presence of Afghan pika ( Ochotona cf. rufescens ) in AH IVc, along with a decrease in the number of rodents between AHs IVd and IV, may suggest a short phase with slightly lower temperatures and/or drier conditions 61 . Finally, hominin remains have not been unearthed at Ghar-e Boof so far.…”

“…These sediments derive primarily from aeolian processes and the effects of gravity, which includes rocks and silts detached from the cave walls and roof 60 . The hominin occupation of the site spans from the MP or MIS5a to the historical period (Table S1 61 , and references therein).…”

“…Paleoenvironmental data inferred from the small vertebrate record of Ghar-e Boof, including small mammals, reptiles, amphibians, and fish, show that during most of the Late Pleistocene, the landscape around the site was mainly dominated by warm, arid conditions with dry, open meadows, shrublands and rocky terrain, and water sources nearby 61 . The sample size for small vertebrates is relatively small for some layers and environmental interpretations must be drawn with caution.…”

A geometric morphometric analysis of variation in Australian frog ilia and taxonomic interpretations

“…Using ilial characters to diagnose fossil species is still regarded as one of the best ways of distinguishing taxa at the specific, generic and family levels (Bever, 2005; Blanco‐Lapaz et al, 2022). The use of some ilial features to differentiate anuran taxa has been somewhat controversial (Bever, 2005; Roček et al, 2013), such as use of ilial characters to distinguish 27 species of Bufo (Bever, 2005).…”