FLIGHTLESS BIRDS. 



MATTHEW D.WENPOKT HILL. ^LA.. F.Z.S. 



The powt-r of fli,t;lit is uiidoulitcdly one of the most 

 marked characteristics of hirds. Yet we ktiow that 

 time and again birds belonging to widely different 

 orders have lost it, accompanied to a greater or less 

 extent by atrophy of the wings and pectoral arch. 

 It is interesting to consider, as far as possible, what 



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Figure 1. 



Hcspcrornis rcgalis Marsh (restored) from the 



Cretaceous of North America. 



changes in environment ma\- have brought about 

 such striking modifications, .\lthough the absence 

 of enemies, and abundance of food close at hand 

 mav suggest reasons for the loss of flight in such 

 birds as the Kiw i and Owl Parrot of New Zealand, 

 yet it is probable that here, as elsewhere, the law of 

 correlation of structures, about which at present we 

 know so little, has played a part in the transforma- 

 tion, coupled with a change in the habits and 

 circumstances of the ancestors of flightless birds. 

 For there can be little doubt that the reptilian 



cannot be regarded as being in the direct line of 



forerunners of birds generally were terrestrial, and 

 probabh' arboreal, animals, not aquatic, as some 

 writers have suggested. In an_\' case the pterodactyles 



r.fT 



-b 



descent of birds. 



Archaeopteryx Iith(i:^i\iphiijii. the most ancient, as 

 well as the most primitive bird. " created," as 

 Huxlev said, " to prove the truth of the theory of 

 evolution," had well-developed fore-limbs, even if 

 the\' were not ver\' ser\'iceable wings, and hence, we 

 may assume that in all cases flightless birds have 

 descended from flx'ing ancestors. Bearing this in 

 mind, it is certainlv remarkable that one of the most 

 ancient known birds. Hcspcrornis (see Figure 1). 

 fiiund in the Cretaceous shales of Kansas, had lost 

 the power of flight completely. In fact the wing- 

 bones were absent, and the breast-bones and pectoral 

 arch much reduced. The bird was a gigantic diver, 





Figure 2. 



Phororliacus loH}>issinins Ameghino (restored) from 

 the Santa Criu Bed (? Mioceue) Patagonia. 



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