Inopinaves

Inopinaves is a clade of neoavian birds recovered in a compressive genomic systematic study using nearly 200 species in 2015. It contains the clades Opisthocomiformes (hoatzin) and Telluraves (core landbirds); the study shows that the hoatzin diverged from other birds 64 million years ago. Previous studies have placed the hoatzin in different parts of the bird family tree; however, despite its unusual morphology, genetic studies have shown the hoatzin is not as primitive or as ancient as once thought; it could be a very derived bird that reverted to or retains some plesiomorphic traits.
According to Suh "et al". (2016), one of the problems with the conclusions about this novel clade is that independent studies (like Jarvis "et al". 2014 and Prum "et al". 2015) found very dissimilar phylogenetic relationships (like Gruae) using the same probabilistic support, such as bootstrap scores and Bayesian posterior probabilities.