Are flightless birds a reversion?

Perhaps the ostriges which don't fly could be analogous to the coelacanth which after alleged millions of years still does not walk, still having lung-like features and having fins where legs would be had it evolved.

Thus, the result is inconsistent with the traditional understanding of a basal avian divergence between Palaeognathae and Neognathae. The findings suggest that the morphological characteristics of the ratites are secondarily acquired, probably through neoteny and that the ratites are descendants of flying, neognathous ancestors.

We can wonder about the proximal factors (Cubo et al., 2000; Cubo, 2000) underlying the similar patterns of character evolution in the different wing bones of ratites. Ratite wing bones are under-developed and this has been interpreted by Cubo & Arthur (2000) as a case of paedomorphosis (the retention of ancestral juvenile character states in adult stages of descendants, Gould, 1977). Considering that the development of forelimbs is delayed relative to the development of hindlimbs in birds (Carrier & Leon, 1990), either the truncation or the retardation of somatic development (heterochrony) is likely to produce reduction of the size of all wing bones by correlated development (Cubo & Arthur, 2000). Heterochronic changes can be instantaneous in terms of geological time (Gould, 1977) and they are likely to produce patterns of speciational character evolution. Ratite wing bones do not play a function in locomotion, they do not undergo adaptation linked to flight, and this would have contributed to preserve the pattern of speciational character evolution generated by heterochronic changes.