The wood hoopoes are related to the kingfishers, the rollers, and the hoopoe, forming a clade with this last according to Hackett "et al." (2008). A close relationship between the hoopoe and the wood hoopoes is also supported by the shared and unique nature of their stapes. The wood hoopoes most resemble the true hoopoes with their long down-curved bills and short rounded wings. According to genetic studies, the two genera, "Phoeniculus" and "Rhinopomastus", appear to have diverged about ten million years ago, so some systematists treat them as separate subfamilies or even separate families.