Giraffoidea is a superfamily of even-toed hoofed mammals now native only to Africa and North America, the only surviving members of this superfamily are the giraffes (genus Giraffa), okapi (Okapia johnstoni), and pronghorn (Antilocapra americana), the superfamily is further split into two surviving families, which are Antilocapridae (Pronghorn and Fossil Relatives) and Giraffidae (Giraffes and Okapi), this is the most basal extant superfamily of the Pecora infraorder and first existed during the Eocene, it is also one of the only two extant superfamilies of even-toed hoofed mammals to be polytypic, the other is Moschoidea, where the musk deer (genus Moschus) and water deer (genus Hydropotes) of the respective monotypic families Moschidae and Hydropotidae are the sole surviving members, all the other even-toed hoofed mammal superfamilies being Traguloidea, Cervoidea, Bovoidea, Cameloidea, Tayassuoidea, Suoidea, and Hippopotamoidea are all monotypic because chevrotains (family Tragulidae), deer (family Cervidae), bovids (family Bovidae), camels (family Camelidae), peccaries (family Tayassuidae), pigs (family Suidae), and hippos (family Hippopotamidae) are the sole extant families of those respective superfamilies, as for the pronghorn (Antilocapra americana), which is the only extant non-african giraffoid, the pronghorn has five recognized subspecies: the Rocky Mountain Pronghorn (Antilocapra americana americana), the Oregon Pronghorn (Antilocapra americana oregona), the Sonoran Pronghorn (Antilocapra americana sonoriensis), the Mexican Pronghorn (Antilocapra americana mexicana), and the Baja California Pronghorn (Antilocapra americana peninsularis).