2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I39 



Gavin de Beer has added greatly to knowledge of this bird through 

 application of modern methods of examination. De Beer (1954, pp. 

 39-41) has outlined clearly the resemblances found in the two nearly 

 complete specimens preserved in London and in Berlin and has shown 

 that most of the differences between them that have been described 

 either have been misinterpreted or do not rate the value that has been 

 assigned to them. His conclusion is that "proposed generic and even 

 specific distinction between them calls for very critical examination." 

 In his final statement on this part of his study (I.e., pp. 50, 57) 

 he unites both under the name "Archaeopteryx lithographic a Meyer." 



In brief review, formal recognition of the two specimens as repre- 

 sentative of separate species came when Dames (1897, P- 829) named 

 the one in Berlin Archaeopteryx siemensii. Petronievics (in Petro- 

 nievics and Woodward, 191 7, p. 5) considered that differences be- 

 tween the two were of sufficient weight to separate siemensii tenta- 

 tively as the type of a new genus, Archaeornis. In a later study 

 Petronievics (1921, p. 10), after further consideration, was definite 

 in establishing the two in distinct genera and added that they might 

 "vielleicht sogar zu zwei verschiedenen Familien gehoren." In a more 

 detailed account (1925, pp. 67-69) he placed the two in separate 

 families, which he maintained later in a further review (1950, pp. 

 118-120). 



The major points on which Petronievics based his two families have 

 disappeared through the information supplied by de Beer. There re- 

 main, however, distinctions of size and relative proportion, the London 

 specimen being about 10 percent larger in general dimension, with 

 the foot about 25 percent greater. De Beer regards these size char- 

 acters as individual, to be attributed either to age or to sex. Steiner 

 (1938, p. 292), who also has considered the two identical, says that 

 in his opinion the Berlin specimen was a young individual and a 

 female, in contrast to the London example which he believes was a 

 mature male. 



While my personal study of this problem has been confined to views 

 of the London fossil and the nearby cast from Berlin in the British 

 Museum, additional comparisons of casts of the two in the U.S. Na- 

 tional Museum, and examination of published figures, it appears to 

 me that the foot of the Berlin bird not only is smaller but also has the 

 toes of different proportion in relation to one another and to the 

 tarsometatarsus. The wing elements in the two specimens appear 

 quite similar, but the entire leg in the Berlin bird seems more slender. 

 It is possible that these ancient birds, like some reptiles, continued to 

 grow in size for a longer period than is true with modern species, 



