Using abundance data, this study explores quantitative patterns from marine benthos, including implications for paleogeography, depositional environment, stratigraphic position, taxonomic groups (brachiopod or mollusc), substrate preferences, and ecological niches. Twenty-nine brachiopod- and bivalve-dominated fossil assemblages from the Pennsylvanian and Early Permian of North and South America, Thailand, and Australia were analyzed from carbonate-platform environments; specifically, Nevada, Kansas, Oklahoma, Texas, Utah, New Mexico, Venezuela, Kanchanaburi (Thailand), and Queensland (Australia). Samples were categorized by paleogeographic location, depositional environment, and age to help differentiate factors controlling the faunal patterns. Pooled from primary and summary literature resources, 336,321 specimens were identified to genus level and classified in terms of taxonomic membership, substrate preference, and ecological niche. Data were analyzed using detrended correspondence analysis (DCA) and multi-response permutation procedure cross-validated a-priori categories (e.g., paleogeography, depositional environment, stratigraphic position, and specimen ecology). Multivariate analyses indicate that the separation between genera and the orthogonal trends implies that paleoecological patterns within the studied late Paleozoic faunal associations were influenced strongly by the abundance of sessile versus mobile faunal components.