This record contains the final n=28 mammal dataset (body mass, maximum lifespan, and the Pace-Standardized Lifespan proxy, PSL = LS × M^(-0.25)), R scripts to reproduce OLS/PGLS/ANOVA analyses, and the 100-tree posterior subset used to assess phylogenetic uncertainty. The 100-tree subset was sampled with set.seed(1) from the Upham et al. (2019) 10k node-dated DNA-only posterior phylogenies archived on Dryad (DOI: 10.5061/dryad.tb03d03).