by Xiaojia Zhu, Rui Bi, Haotian Yan, Qiyu Wang, Lin Li, Hongli Li, Long-Bao Lv, Cirong Liu, Yong-Gang Yao The tree shrew ( Tupaia belangeri ), phylogenetically proximal to primates, serves as a critical model for evolutionary neurobiology and disease mechanisms. High-resolution MRI provides a unique opportunity to refine its neuroanatomical architecture and facilitate cross-species comparisons. Here, we present a comprehensive, ultra-high-resolution (9.4T) MRI atlas of the tree shrew brain, integrating structural and diffusion imaging to resolve fine-scale anatomical features and whole-brain connectivity gradients. Our comparative analysis characterizes the tree shrew as a distinct evolutionary mosaic: the cerebellum exhibits pronounced volumetric expansion and connectivity gradients recapitulating those of primates, whereas the hippocampus retains rodent-like architectural scaling yet preserves evolutionarily conserved longitudinal functional axes. Moving beyond these regional adaptat