The smilodontine felid Megantereon hesperus is described from the latest Hemphillian (early Pliocene) Upper Bone Valley Formation of central Florida. The Florida record marks the earliest known occurrence of Megantereon and adds to our poorly known record of this genus in North America. Old World records suggest immigration of Megantereon to Eurasia and Africa in the early Villafranchian (middle Pliocene). The genus is not known in North America after the middle Blancan (middle Pliocene).--Modified journal abstract.