Savanna ecosystems and mammalian adaptations in Mid-Miocene Northern China.

The paleoenvironments and ecosystems of northern China during the Miocene (ca. 23-5.3 Ma) are complex topics, especially concerning the uplift of the Tibetan Plateau on the surrounding areas and the ecological adaptations of mammals as a consequence. Our data integrated stable carbon and oxygen isotope analysis, cenograms, and hypsodonty of herbivorous mammals. The results reveal open, arid, savanna-like habitats in the Junggar Basin during the late early Miocene (ca. 20.4-15.9 Ma). These habitats subsequently spread to northern China by the late Miocene (ca. 11.6-5.3 Ma), driving mammalian adaptation. Large herbivores, particularly proboscideans and rhinocerotids, exhibited strong adaptations to these new open environments, while smaller taxa maintained a preference for more closed, forested habitats. Additionally, during global climate changes, biodiversity declined, indicating increased ecological pressure. Despite these changes, faunal diets in the Junggar Basin remained consistent. Our findings contribute to understanding mid-Miocene paleoecology in northern China and the adaptive strategies of mammals in response to environmental changes.