502 



CENOZOIC TIME. 



3. Birds. — The Eocene and Miocene have afforded remains of spe- 

 cies related to Waders, an Owl, a bird near the Woodpecker, some 

 web-footed species allied to the Gannet ; and the Pliocene, remains of 

 a large Eagle, a Cormorant, and other kinds. The Diatryma gigantea 

 Cope, from the early Eocene of New Mexico, was larger than the 

 Ostrich. 



4. Mammals. — Tertiary Mammals frequented in vast numbers the 

 shores of the great fresh-water lakes of the Rocky Mountain area, as is 

 proved by the bones that have been found in . the lacustrine deposits. 



Figs. 914-916. Fig. 917. 



915 



Teeth of Sharks : Fig. 914, Carcharodon augusti- 

 deus ; 915, Lamnaelegans ; 916, Notidanus prim- 

 igenius. 



Tooth of Zeuglodon cetoides (X% 



These ancient bone-beds remained almost unknown to science until the 

 year 1847 ; and now, through the labors of explorers, and the works 

 of Leidy, followed by the memoirs of Marsh, Cope, and others, the 

 number of known species far exceeds that of existing North American 

 Mammals. The Laramie beds contain Cretaceous Saurians (Dino- 

 saurs) but no Mammals; the strata above, commencing with the Wah- 

 satch group, have no Cretaceous Saurians, but abound in Mammals. 

 The abrupt transition remains unexplained. 



The marine Tertiary of the Continent has afforded remains of but 

 few species of Mammals ; for seashores are not their ordinary resort, 

 except for some aquatic kinds. 



(1.) Eocene. — The marine Eocene beds of the Lower Claiborne 



