794 GEOLOGY 



Birds. Fossils of ancestral gulls, herons, flamingoes, alb at ,r< 

 buzzards, falcons, eagles, owls, woodcock, quails, plover- 

 ostrich-like, flightless birds of great size, with not a few forms o: 

 doubtful interpretation, have been found, showing great deploy 

 ment of this class. 



Reptiles and amphibians. One of the greatest contrasts ii 

 geological history is found in comparing the size, power, and multi 

 tude of the Cretaceous land reptiles with those of the Eocene. 

 the great saurians, only a few lived on into the Eocene and the\ 

 did not live long. Land reptiles seem to have become rare earl} 

 in the period. There were turtles on both land and sea, and SOUK 

 of them attained large size. There were crocodiles which belongec 

 about equally to land and water; also snakes, some of them large 

 Amphibians were present, but apparently not abundant. 



The insect life. There has been little important change in tlu 

 insect world since the beginning of the Cenozoic era. Few nev 

 families have appeared, though the genera and species have 

 changed. 1 



Marine Life 



The name Eocene, founded upon the presence of a small per- 

 centage (less than 5%) of living species among the marine inverte- 

 brates, implies their stage of advancement. Not only were the 

 existing orders, families, and genera established, with some e 

 tions, but even the present species had begun to appear. The 

 changes that follow from this time on are valuable as criteria of 

 correlation, climate, migration, and other elements of the later 

 history, but they do not record profound biological transformations 

 They stand in striking contrast with the radical and rapid evolution 

 of the mammals. 



Geologically, the most striking feature of the marine E< 

 life was the extraordinary abundance and size of the foravt 

 (Fig. 534). Reference has already been made to the prodigious 

 abundance of the nummulites. Gastropods and pelcc >//><>< I* of 

 modern types were very numerous, but cephalopods were much ls< 

 important than in the Cretaceous. Sea-urchins continue! 1 to )>e 



1 Mono. XXI, U. S. Geol. Surv., 1893, p. 1. 



