A SKELETON OF HESPERORNIS 

 By FREDERIC A. LUCAS 



The announcement by Professor Marsh of the discovery of birds 

 with teeth in the chalk-beds of western Kansas was not only im- 

 portant from a scientific standpoint, but aroused much popular in- 

 terest. Unfortunately, toothed birds are not merely rare but usually 

 are in a more or less imperfect condition ; the teeth, too, are so small 

 and so few remain in the jaws that a specimen of a toothed bird is 

 apt to prove a disappointment to the few who see them. In this last 

 particular the example of Hespcrornis regalis (plate xxvii), which 

 formed a portion of the exhibit of the U. S. National Museum at 

 the Buffalo Exposition, is no exception to the general rule ; it is, 

 however, one of the most complete specimens yet discovered, being 

 the first sufficiently well preserved to admit of its being mounted. 

 The mounting of this specimen revealed the fact that in the position 

 of its legs Hesperornis was not only different from any modern bird, 

 but different from all other birds. In ordinary waterfowl, such as 

 ducks and geese, the legs, when swimming, are beneath the body, 

 and this is also the case in such highly specialized divers as loons 

 and grebes, in which the legs are placed far back. But in Hesperor- 

 nis the articulations of the leg-bones were such as to show that in 

 swimming the legs must have stood out, almost at right angles to 

 the body, suggestive of a pair of oars. This also suggests that the 

 legs, like oars, may have been moved together and not alternately, 

 since an alternate motion of the legs would have had a tendency to 

 throw the body from side to side. It is a little difficult to see just 

 what advantage could be derived from such a method of swimming 

 unless it was for rapid movement at the surface. This peculiar 

 position of the legs was not found in the Cretaceous diver Baptornis, 

 also from western Kansas, in which the legs were situated as is 

 customarily the case. 



The present specimen of Hespcrornis also showed that in the 

 structure of its shoulder girdle the Cretaceous bird was more like 

 modern birds than heretofore supposed. These details will be found 

 described in the Proceedings of the U. S. National Museum for 

 1903. pp. 545-552. 



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