THE CRETACEOUS PERIOD 261 



pelled to assume a great variety of forms, in the vain attempt to 

 adapt itself to the new environment, and thus to escape its in- 

 evitable destiny. The curve of its rise, culmination, and decline 

 reached its highest point just before it was destroyed. The wave 

 of its evolution crested and broke into strange forms at the moment 

 of its dissolution." 1 Very few if any Ammonites crossed the line 

 into the early Cenozoic, and such an abrupt termination of so 

 abundant and diversified a group of animals has rarely been equaled 

 in the history of the animal kingdom. Belemnites still were abun- 



Fig. 162 

 A Cretaceous Teleost Fish, Osmeroides Lewesiensis, restored. 



dant and these, too, showed a remarkable decline by the close of 

 the Cretaceous. 



Arthropods. — Broadly considered, the Cretaceous Arthropods 

 were much like those of the Jurassic, though the short-tailed 

 Decapods (Crabs) increased notably. Most of the Arthropods 

 were of pretty modern aspect, though the species were quite 

 different from those of today. 



Fishes. — From the standpoint of evolution, a very important 

 change took place among the Fishes. Sharks were common, having 

 left an almost incredible number of fossil teeth. For the first time 

 the Teleosts (typical bony Fishes), which were introduced in a 

 small and primitive way in the Jurassic, predominated over the 

 Ganoids. Many Cretaceous Teleosts belonged to families or genera 

 which still exist, such as Salmon, Herring, Bass, Cod, etc. Other 

 types were more characteristic of the time. 



Amphibians. — These were of quite modern appearance and 

 they occupied much the same relatively subordinate position that 

 they do today. 



1 J. Le Conte: Elements of Geology, 5th ed., pp. 499-500. 



