PhaFoS: A Global Database of Phanerozoic Foraminiferal Size

Abstract. Body size is a key phenotypic trait of living organisms, reflecting ecological function and individual metabolism. Evolutionary changes in body size also provide information on interactions between the organisms and their changing physical and biotic environments. Despite the utilitarian value of body size for understanding evolution and past environments, we lack a standardized, occurrence-based, Phanerozoic body size database for most groups of organisms, limiting large-scale studies of size evolution and size-environment interactions. Foraminifera are an ideal group to fill this data gap, given their abundant fossil record, extensive palaeogeographic distribution, and sensitivity to environmental changes. Here, we present PhaFoS, short for Phanerozoic Foraminifera Size database. PhaFoS compiles 118,885 specimens, of which 103,121 from 963 published papers and the remaining 15,764 from our field colletions, representing 4,167 genera and 34,256 species. Each record is linked to standardized and queryable metadata fields, including test volume (log₁₀ μm³), taxonomy, stratigraphic age, and both modern and paleogeographic coordinates. This database can be used to quantify temporal and spatial patterns of foraminiferal body-size over the Phanerozoic, and to explore the body size relationships with environmental conditions and their changes. The data files described in this paper are available at https://doi.org/10.5281/zenodo.20777319 (Feng et al., 2026).