The Family Opisthocomidae is commonly known as the hoatzin family. Synonyms for this family include the Opisthocomidae family, Hoatzinidae family, and the stinkbird family. This group of animals is native to South America and is characterized by their distinctive odor, as they have a unique digestive system that produces methane gas. The hoatzin family is made up of two species, the hoatzin and the opisthocomus, and they are both herbivores that feed on leaves and fruits. These birds have a prehistoric appearance with a unique clawed wing structure, making them a fascinating and unique family in the animal kingdom.