Stratigraphic Resolution in the Nihewan Basin: Implications for Early Hominins

The Nihewan Basin in Hebei Province, Northern China, provides a key terrestrial archive of faunal, environmental and climatic changes throughout the Pleistocene, and preserves one of the most informative successions of Paleolithic archeological sites in Eurasia. So far, the earliest indications of human presence in the Nihewan area are dated to ca 1.66 Ma. This study, part of a consortium project bringing together archaeologists, palaeontologists, geologists, and computer scientists, refines the stratigraphic framework of the region, investigates depositional environments, and examines the relationship between climatic shifts, faunal evolution and human occupation in the area. The classic Nihewan Fauna, representing the early Pleistocene Asian Land Mammal Age (Nihewanian), has long been central to bio- and chronostratigraphic correlations, yet its precise stratigraphic context remained unresolved. By reassessing 30 original excavation sites through field surveys and museum collections, our study provides the first calibrated stratigraphic profile of the Nihewan Formation in Xiashagou and suggests an age of ~2.4–1.8 Ma for the classic Nihewan Fauna. Building on this chronological framework, the second part of this study focuses on the Shanshenmiaozui sequence, where a high-resolution stratigraphic investigation reveals a temporal span from ~1.8 Ma to the present. This work establishes the earliest well-dated archaeological finds in the region at 1.8 Ma, marking a major contribution to East Asian Paleolithic and hominin research. The timing of early human dispersal into East Asia remains one of the most debated topics in archaeology, and reliable dating of Early Pleistocene Paleolithic sites is essential for addressing this issue. The Nihewan Basin provides one of the most robust records of early hominin presence in the region. Lithofacies analysis indicates that the classic Nihewan fauna mainly yields from deposits consisting of fluvial and alluvial fan sediments, whereas the Shanshenmiaozui site with artefacts represents distal fluvial fan–floodplain setting transitioning to marginal lacustrine environments, with a constant eolian dust supply. Faunal taxonomic composition and dental ecometric data suggest a shift from more diverse temperate conditions with elements of forest and shrublands before 1.8 Ma to an increasingly arid shrubland-dominated environments thereafter. These findings offer critical insights into palaeoenvironmental changes during early hominin occupation in East Asia, shedding light on the ecological contexts that shaped early human dispersals.