We analyze the interrelationships of the higher (Pecoran) ruminants, and suggest possible relationships between these families and the various genera of the polyphyletic assemblage "Gelocidae." We also review the developmental processes of the cranial appendages of the living homed ruminant families, and conclude that giraffid ossicones, bovid horns, and cervid antlers cannot be considered to be homologous with each other. The characters that have been used in the past and in this paper to distinguish pecoran families are discussed and evaluated.
Within living pecoran families the Giraffidae are the most primitive, and the Moschidae and Antilocapridae are conjoined with the Cervidae in the superfamily Cervoidea, with antilocaprids being closer to cervids than are moschids. The Moschidae includes Moschus, the extinct European genera Dremotherium, Micromeryx, and Hispanomeryx, and the North American blastomerycids.
The Cervoidea includes the primitive extinct Eurasian genera Eumeryx and Rutitherium, and (more closely related to the other cervoids) the extinct African genus Walangania. The grouping Eucervoidea is proposed for a clade within the Cervoidea containing the Antilocapridae, the Cervidae, and the extinct families Palaeomerycidae and Hoplitomerycidae (which are deemed as closer to the Cervidae than are the Antilocapridae). The Palaeomerycidae contains the Old World genera Palaeomeryx, Amphitragulus, possibly also Prolibytherium, and the North American dromomerycids. The Hoplitomerycidae contains the European genera Hoplitomeryx and Amphimoschus. The European genus Triceromeryx remains as cervoid incertae sedis. A superfamily Giraffoidea is proposed to include the Giraffidae, the extinct family Climacoceridae, and possibly also the extinct African genus Propalaeoryx.