ANCIENT BIRDS 217 



the end of the toes must have been between five and six feet (see 

 Plate XXXIV.). Its habits are clearly indicated by the skeletons 

 described by Professor Marsh in his splendid monograph on The 

 Extinct Toothed Birds of North America. No living birds possess 

 teeth in their jaws, so that the presence of such in Hesperornis 



FIG. 81. Skeleton of Hesperornis regalis, from Cretaceous strata, North America. 



(After Marsh.) 



and other birds of the Cretaceous period at once separates them 

 from those of the present day. It cannot be doubted that this 

 antique diver was carnivorous ; it probably devoured fishes. The 

 teeth were set in a groove, and old ones were replaced by young 

 ones growing up from inside the fang. The breast-bone (sternum) 

 was entirely without a keel. The single thin wing-bone (humerus) 



