An Additional Character Linking Ratites and Tinamous, and an Interpretation of Their Monophyly

Abstract

Examined ratites (ostriches, rheas, emus, cassowaries, kiwis, and moas) and tinamous share a conformation of the rhamphotheca not found in other birds. This is interpreted as an additional piece of evidence that resemblances among this group are to be attributed to monophyletic origin rather than to convergence. Their monophyly is thought to be at approximately the family level, with several lines of descent from a family of "proto-tinamous" having independently attained the "ratite grade." Classification of ratites and tinamous should reflect this relationship without exaggerating their differences from other birds.