Paleozoological research on flat-headed peccary (Platygonus compressus) and dire wolf (Canis dirus) remains from Peccary Cave, Arkansas, provides information on the ecology and extinction of these taxa. The peccary assemblage is large, totaling nearly 4,000 specimens, and includes all skeletal elements, while the dire wolf assemblage includes only a handful of specimens. A minimum of 61 sub/adult peccaries, 15 fetal/neonatal peccaries, and 3 dire wolves are represented in the collection. Peccaries died naturally in the cave. The dire wolf remains were transported into the cave by colluvial or fluvial processes. Five direct AMS ages on peccary and three direct AMS ages on dire wolf bone range between approximately 25,500 cal B.P. and 21,300 cal B.P., and indicate both assemblages are time-averaged accumulations. Dire wolves did not den in the cave or transport peccary carcasses there, however bulk stable isotopes indicate that dire wolves likely preyed on peccaries regularly. Serial isotopic sampling of two peccary canine teeth paired with stable isotope values from bone indicates the animal foraged primarily on C3 plants year-round, mostly legumes. Early Late Glacial Maximum conditions on the Ozark Plateau were warming and drying, which contributed to deficits in peccary reproduction and, ultimately, to the regional extinction of the taxon, and by extension, dire wolf.