A SYSTEMATIC CLASSIFICATION FOR THE BIRDS OF 

 THE WORLD, REVISED AND AMENDED 



By ALEXANDER WETMORE 

 Assistant Secretary, Smithsonian Institution 



The present classification is offered as the result of further study, 

 since publication of a previous paper on the same subject in 1930/ 

 of the intricate relationships of our forms of birds, including the 

 fossil species, as far as at present known. As in the previous list, 

 only such changes from the current order have been accepted as 

 seem to be definitely settled and established, leaving various other 

 proposals still in abeyance until they have been developed by further 

 research. 



The major changes from the previous list have been the segre- 

 gation of the penguins in a distinct superorder, Impennes, in accor- 

 dance with Lowe's investigations,^ and a revision of the fossil families, 

 following the appearance of Lambrecht's Handbuch der Palaeorni- 

 thologie and as the result of certain studies by the writer. Lambrecht's 

 proposal to place the Hesperornithidae near the grebes and loons, 

 and the Ichthyornithidae near the Diatrymiformes and the pigeons, 

 to me does not seem justified. The resemblances in form that Lam- 

 brecht cites as basis for his action, while pertaining to two different 

 schemes of life (one natant and the other volant), include limiting 

 factors that have confined the evolution of birds as a whole within 

 narrow lines, compared, for example, to what has taken place in 

 reptiles and mammals. In view of this, the possession of teeth and 

 other peculiarities assume greater importance in weighing probable 

 evolutionary origins and trends. It seems probable that teeth were a 

 characteristic of Cretaceous birds that disappeared with advance into 

 the Tertiary period. 



Under the Galli formes the quails (formerly the family Perdicidae) 

 have been united with the Phasianidae, as there appear to be no 

 trenchant characters to separate the two. Under the Charadrii formes 



' A systematic classification for the birds of the world. Proc. U.S. Nat. Mus. 

 vol. 76, art. 27, Jan. 8, 1930, pp. 1-8. 

 ^ See Proc. Zool. Soc. London, 1933, pt. 2, pp. 483-538. 



Smithsonian Miscellaneous Collections, Vol. 89, No. 13 



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