Classification As said under "Struthioniformes", Tinamous and Ratites are no longer considered two sister clades originating from the Paleognath ancestor. Tinamous are in fact nested within the nonostrich ratite tree and they are placed as sisters to the extinct New Zealand Moas. This pattern is best explained by concluding that flight was lost more than once in the descent of the volant paleognath ancestor.
the 47 species of ground-dwelling birds found in Central and South
America, superficially resemble partridges and quail but have limited
flight capability, preferring to walk or run rather than fly. Most
inhabit forests, but some live in more open terrain. Drably coloured,
tinamous blend into their surroundings, where they generally live alone
or in small groups.
tinamou (2011). Encyclopædia Britannica Ultimate