Discoveries of vertebrate fossils near Charleston and Myrtle Beach, South Carolina, and in Brunswick County, North Carolina, have provided new records of 37 Pleistocene mammal taxa on the Atlantic Coastal Plain. Two North Carolina specimens of early Irvingtonian age are the first records of the genus Neofiber diluvianus-like animals south of Pennsylvania and are the oldest evidence of the genus Neofiber. Additional records of Neofiber alleni True from South Carolina also are included. The holotype molar of Neochoerus pinckneyi Hay is found to be of Mid-Pliocene age instead of Pleistocene, and the holotype premolar of Alces runnymedensis Hay is referred to Cervalces. Early Pleistocene remains of Dasypus, Eremotherium, Equus, Cervus, and Hydrochoerus in South Carolina are documented, along with new records of Tremarctos floridanus (Gidley), Arctodus pristinus Leidy, Smilodon fatalis (Leidy) Castor canadensis and Mammut americanum (Kerr) from South Carolina. the first fossil records of Erethizon dorsatum Linnaeus, Panthera le atrox (Leidy), Puma concolor Linneaus, Erignathus barbatus Gill, Hemiauchenia cf. H. Macrocephala (Cope), Cuvieronius Osborn, and Monachus tropicalis (Gray) in South Carolina are reported, as well as the first record of Monachus from Georgia. A mandibular ramus tentatively referred to Puma concolor by Allen (1926) is redetermined as Miracinonyx inexpectatus and is the first evidence of cheetah-like cats in the fossil record of South Carolina. A well preserved right mandibular ramus from Charleston County is designated as the neotype of Arctodus pristinus Leidy, 1854. The boundary of the Irvingtonian/Rancholabrean Land Mammal Age is placed at 0.24 Ma on the basis of a Bison astragalus from the Ten Mile Hill (Late Middle Pleistocene).
