Kelenken is assigned to the subfamily Phorusrhacinae, a subfamily of terror birds up to 3 meters high, but somewhat slender and decidedly more nimble than the Brontornithinae, together with: Devincenzia, Late Oligocene to Early Miocene (Deseadan) Fray Bentos Formation of Uruguay , Kelenken, Colloncuran of Río Negro Province, Argentina; largest known phorusrhacid, Phorusrhacos, Early to Middle Miocene (Santacrucian) Santa Cruz Formation of Argentina, Titanis, Early Pliocene to Early Pleistocene (Blancan) of Florida and Texas.