An order of birds having zygodactyl feet (two toes are in front and two behind) in which the fourth toe is reversed, but not having any close relationship to other birds with this foot structure, such as the parrots or piciforms. The relationship of the touracos to the cuckoos has been strongly debated and is still unresolved. However, this conclusion is very controversial because the hoatzin possesses an anisodactyl pattern of the toes (three toes are in front and one is in back); thus, many authors still place the hoatzin in its own order next to the Cuculiformes.