xHE UrIc.In of Feathers from the Scales of Eeptiles. (>" 



THE ORIGIN OF FEATHERS FROM THE SCALES 



OF REPTILES. 



By Professor J. E. Duerden, M.Sc, Pli.l)., P.Z.S., 

 (xiootfonteiii School of Aii'viculture. 



South Africa takes a special interest in tlie pluniag-e of birds. In 

 pre-war days the annual income to the Union from the exportation 

 of ostrich feathers overseas amounted to almost three million pounds 

 sterling, derived from nearly one million domesticated ostriches. 

 During the years of the war and of the economic depression which 

 have followed the value of the plumes exported has been greatly 

 reduced, reaching only about half a million pounds last year (1921). 

 There is every indication, however, that with the restoration of settled 

 economic conditions, the ostrich will be restored once more to the 

 proud position which it formerly occupied among the agricultural 

 efforts of the country. 



One of the many problems confronting zoologists is that con- 

 cerned with the origin of feathers, as a covering of birds, and as a 

 means of flight. No structure at all resembling them is to be found 

 in any other animal to show the course along which they have evolved. 

 Since the days of Huxley, however, very little doubt has remained 

 that in some manner feathers have been derived from the scales of 

 reptiles, the group of animals which, includes the living lizards, 

 snakes, crocodiles, and tortoises, and numerous extinct forms. 



Professor Huxley proved conclusively that in many ways the 

 scale-covered, cold-blooded reptile is closely related to the plumage- 

 covered, hot-blooded bird, and subsequent investigations have served 

 to support the relationship. From this the view naturally followed 

 that the feathers of birds, hoAvever different they may at first sight 

 appear, have in all probability originated from the scales of reptiles. 



It Avas known that scales and feathers are much alike during the 

 early stages of their development, both being formed as upgroAvtlis of 

 the outer layer of the skin or epidermis, followed by the ujuler layer 

 or dermis, which supplies the nutritive blood plasrjia; and it has been 

 generall}^ assumed that in some manner the scales of reptiles, such 

 as those of the lizard, had become frayed out until thej^ took on the 

 character of feathers. Yery little real evidence in support of the 

 theory has, however, been forthcoming, nor of Iioav the fraying-out 

 first took place. One of the latest contributions is that by Professor 

 Cossar Ewart, Edinburgh University, who, in the September number 

 (1921) of the " Proceedings of the Zoological Society," London, 

 contends that while feathers Avere associated Avith scales in their 

 origin, they yet arose independently of them from the skin. 



Since birds are held to have sprung from reptiles, it folloAvs that 

 the ancestors of birds must have been entirely covered Avith scales, as 

 are all reptiles at the present day. This scaly covering has largely 



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