 The study of cerebellar folding is challenging due to its small size and abundance of folia, but an open collection of histological data from 56 mammalian species was used to manually segment the cerebrum in cerebellum, develop methods to measure geometry and thickness of folia, and estimate evolutionary relationships between cerebellar and cerebral anatomy. Results show that evolution follows a stabilizing selection process with two groups of phenotypes changing concertedly through evolution, and a strong correlation between cerebral and cerebellar volumes across species. The study provides new insights into the diversity and evolution of cerebellar folding, mechanisms of folding, and potential influence on brain organization across species. This article was authored by Kothia Hoyer, Nicholas Trout, Alexander Allison de Souza, and others.