Hoatzin

The hoatzin (Opisthocomus hoazin), also known as the stinkbird, or Canje pheasant, is a species of tropical bird found in swamps, riparian forests, and mangroves of the Amazon and the Orinoco Delta in South America. It is notable for having chicks that possess claws on two of their wing digits.
It is the only member of the genus Opisthocomus (Ancient Greek: "wearing long hair behind", referring to its large crest), which in turn is the only extant genus in the family Opisthocomidae. The taxonomic position of this family has been greatly debated, and is still far from clear.              
by wikipedia