 Other species rival the southern ground species in length, at up to about , including the Abyssinian ground hornbill ("Bucorvus abyssinicus"), the great hornbill ("Buceros bicornis") and, probably the longest of all (perhaps exceeding ) thanks in part to its extended tail feathers, the helmeted hornbill ("Rhinoplax vigil").Males are always bigger than the females, though the extent to which this is true varies according to species.The extent of sexual dimorphism also varies with body parts.