554 Comparative Morphology of Chordales 



pertinent to inquire whether our modern ostrich-like birds may not 

 be persisting primitive types tracing back to a point in that "pre- 

 archaeopterygian" period when flight had not yet been fully achieved. 

 Is it possible that capacity for flight has never existed in the ancestry 

 of "Ratitae"? It seems quite safe to answer this question in the nega- 

 tive. The forelimb of the ostrich is vestigial but it is not a vestigial 

 foreleg. It is definitely a reduced wing. It has, in atrophied form, the 

 essential peculiarities of the wing of a good flier. In numerous other 

 respects, especially in possession of well-developed air-sacs and a con- 

 siderable degree of pneumaticity in the skeleton (only in the skull in 

 Apteryx), the Ratitae, except in degree of development of wings, 

 resemble flying birds and, at least so far as the skeleton is concerned, 

 are very unlike Archaeopteryx. 



Scanty fossil remains of birds of the ostrich type date back into 

 middle or early Cenozoic time. Flying carinate birds existed in the 

 late Mesozoic, but no evidence that ratite birds existed then has been 

 found. Two notable examples of ratite birds, the moa (Dinornis) of 

 New Zealand and the elephant-bird (Aepyornis) of Madagascar, 

 became extinct in comparatively recent times. The moas (Fig. 281), 

 some of them 11 feet tall (or more, according to some accounts), were 

 the largest known birds. Their wings were reduced to trivial vestiges, 

 or, in some cases, no trace of wing-skeleton, including the girdles, can 

 be found. In some of the several species of Aepyornis, the birds were 

 of the size of the larger modern ostriches. The wings were vestigial and 

 the legs were of massive build. Although smaller than moas, the 

 elephant-birds laid the largest known eggs. As the story goes, the 

 discovery of skeletal remains of the birds followed recognition of the 

 fact that certain curious domestic utensils used by the Madagascan 

 natives, especially as receptacles for rum, were eggshells. The dimen- 

 sions of the larger eggs are given as somewhat over 13 inches in long 

 diameter and 9% inches in short diameter. Aepyornis may have been 

 the gigantic "roc" of Arabian mythology. The remains of both the 

 moa and the elephant-bird are found associated with early human 

 remains in such a way as to make it probable that the birds lived 

 contemporaneously with the early human inhabitants of their respec- 

 tive islands. 



Among recent birds are many instances of reduction or loss of 

 capacity for flight, associated with assumption of either terrestrial or 

 aquatic habits of living. The South American tinamou has small 

 wings incapable of more than a short, low flight (several hundred 

 yards) and resorts to flight only as a desperate measure. It is a rapid 

 runner, although the legs are short and stout. The sternal carina, 

 however, is fairly well developed. Most of the Galliformes are 



