Condylus tertius (CT) is a developmental condition affecting the craniovertebral junction. Its prevalence was estimated to be less than 5% and can be asymptomatic or debilitating. This study aims to search for CT in the Coimbra Identified Skeletal Collection (CISC) and to do a bibliographic review of this neglected developmental defect. Two hundred individuals, from both sexes, and with ages at death between 30 and 59 years old from the CISC were observed macroscopically to search for CT. A bibliographic survey of the bioarcheological and clinical literature was conducted. One female individual (0.5%) had CT with irregular margins and porosity. In addition to the CT, the odontoid process of the axis had an increase in its retroversion angle and looked enlarged. The vertebra L1 showed hypoplasia of the right transverse process and the sacrum presented incomplete sacralization of the vertebra L5. In archaeological derived individuals only eight cases of CT were recognized in the literature survey, the oldest dating from the Pleistocene. This study draws attention to this trait and its diagnosis in skeletal individuals and alerts to the possible coexistence with other developmental defects in transitional vertebrae.