Oligocene-Miocene marine mammals from Belgrade Quarry, North Carolina

A diverse but fragmentary assemblage of fossil cetaceans is reported from the Oligocene-Miocene Belgrade Formation of North Carolina. This assemblage preserves many odontocetes including four xenorophids (Albertocetus, Echovenator sp., cf. Cotylocara, and Xenorophus sp.), a possible waipatiid (cf. Waipatiidae), a giant agorophiid-grade dolphin (Ankylorhiza), a shark-toothed dolphin (cf. Squalodon), longirostrine “swordfish” dolphins (Eurhinodelphinidae), a longirostrine eoplatanistid dolphin (cf. Eoplatanista), a longirostrine squalodelphinid dolphin, a possible early delphinidan (Kentriodontidae), as well as an eomysticetid baleen whale (Eomysticetus sp.) and sirenian fragments. Most of these taxa are characteristic of or unique to Oligocene deposits (Xenorophidae, cf. Waipatiidae, Ankylorhiza, Eomysticetus) whereas others are more typical of early or middle Miocene deposits (cf. Eoplatanista, Eurhinodelphinidae, cf. Squalodon, Squalodelphinidae, Kentriodontidae). The Belgrade Formation at Belgrade Quarry is dated to 25.95–21.12 Ma, approximating the Oligocene-Miocene transition. The transitional composition of the Belgrade cetacean assemblage suggests gradual changes between Oligocene to Miocene cetacean faunas, to be verified by the discovery of more complete remains from the poorly sampled earliest Miocene (Aquitanian).