Recently collected specimens of the extinct tayassuine peccary "Cynorca" occidentale (and another indeterminant tayassuid) are described from new excavations along the southern reaches of the Panama Canal. Fossil peccaries were previously unknown from Panama, and these new tayassuid specimens therefore add to the extinct mammalian biodiversity in this region. "Cynorca" occidentale occurs in situ in the Centenario Fauna (new name) from both the upper part of the Culebra Formation and overlying Cucaracha Formation, thus encompassing a stratigraphic interval that includes both of these formations and the previously described and more restricted Gaillard Cut Local Fauna. "Cynorca" occidentale is a primitive member of the clade that gives rise to modern tayassuines in the New World. Diagnostic characters for "C." occidentale include a retained primitive M1, reduced M3, and shallow mandible, and this species is small relative to most other extinct and modern tayassuine peccaries. Based on the closest biostratigraphic comparisions (Maryland, Florida, Texas, and California), the presence of "C." occidentale indicates an interval of uncertain duration within the early Hemingfordian (He1) to early Barstovian (Ba 1) land mammal ages (early to middle Miocene) for the Centenario Fauna, between about 19 and 14.8 million years ago. Based on what is known of the modern ecology of tayassuines and previous paleoecological interpretations for Panama, "C." occidentale likely occupied a variety of environments, ranging from forested to open country habitat mosaics and fed on the diverse array of available plants.
