"Rediscovered" fossil specimens, those that have lingered in university or museum collections for decades before being studied, can provide new context on the anatomy, distribution, and paleobiology of established species. In this study, a partial thoracic vertebra rediscovered in Wichita State University collections that had been labeled as an indeterminate whale bone is interpreted as an additional specimen of Belosphys spinosus. An enigmatic species of odontocete whale, Belosphys spinosus has previously been reported from the Lower Miocene Calvert Formation in southern Maryland, where it is known from partial thoracic and lumbar vertebrae. Comparisons between the rediscovered vertebra and literature descriptions of known Belosphys spinosus specimens have revealed several anatomical traits that support a referral to this species. Locality data associated with the described specimen indicates that it was collected from the Middle Miocene Choptank Formation, which directly overlies the Lower Miocene Calvert in southern Maryland. Thus, while the new specimen does not provide further anatomical information about Belosphys spinosus or expand its geographic range, it extends the temporal range of this mysterious cetacean species by a span of 1-2 million years into the Middle Miocene. Additionally, the vertebra increases the number of whale species in the Choptank Formation, highlighting the high diversity of marine vertebrates in this region during the Middle Miocene.