CHAPTER VII 



THE AMERICAN TOOTHED-BIRDS 



(SUBCLASS Neornithes) 

 (Orders Hesperornithiformes and Ichthyornithiformes) 



\ N point of time the next birds of which we have any knowledge, in the 

 line of evolution between the Lizard-tailed birds and those of the pres- 

 ent, are the so-called American Toothed-birds, the remains of which 

 came to light some thirty or more years ago in the Cretaceous rocks of 

 western Kansas. If it is true, as has been stated, that the bird-like elements in Ar- 

 chaopteryx amount to three fourths, and the reptilian features to no more than one 

 fourth, of its make-up, then the Toothed-birds, although presenting a number of 

 anomalous characters, are perhaps entitled to be called nine tenths "bird, "for they 

 exhibit a very distinct advance over the Lizard-tailed birds, which brings them in 

 some respects quite close to if not indeed fully abreast of modern birds, and this 

 be it remembered at a time so remote as the Cretaceous period. As the name 

 implies, their most marked characteristic is the possession of distinct teeth, a 

 character which they share in common with the Archaopteryx, but which sharply 

 distinguishes them from all other known birds, either fossil or living. The man- 

 ner in which the teeth are implanted in the jaw, as well as modifications of the 

 skeleton which have resulted from very different modes of life, serve as a basis 

 for dividing the Toothed-birds into very distinct groups which are thought to be 

 of sufficient importance to rank as separate orders. 



Hesperornis. The first of these orders to be considered is typified by what 

 has been named the Hesperornis, signifying literally "western bird," since at 

 the time of its discovery the locality where it was found was beyond the western 

 limits of extensive settlement. Hesperornis was a flightless, swimming and 

 diving bird of great size, its length being nearly four feet. The skull was rela- 

 tively small, while the bill or jaw was very long and slender, with its rami or 

 branches united in front by a ligament only, and the component bones free from 

 one another, as in reptiles. The teeth, which were replaced by a new one grow- 

 ing inside of and ultimately absorbing and pushing off the old one, are set in a 

 continuous groove, and fill the lower mandible quite to the tip, while in the 

 upper mandible they are confined to the basal portion or maxilla. The long and 

 slender neck is made up of some seventeen saddle-shaped vertebrae, and was 

 doubtless capable of rapid flexure and was thus of assistance in securing its 

 prey. The wing was very much reduced, being represented by the humerus 

 only, and was probably concealed beneath the skin or in any event among the 



56 



