Opisthocomimorphae

This superorder is represented by a single order, Opisthocomiformes, with only one species, Opisthocomus hoazin, in the family Opisthocomidae. 

 

References

Jarvis, E.D. et al. (2014), Whole-genome analysis resolve early branches in the tree of life of modern birds, Science 346, 1320-1331. (pdf)