BULLETIN 



OF THE 



SoutHern Galilornla flcademy ol Sciences 



VOL.2. LOS ANGELES, CAL, rCBRU/^RV I, 1903. NO. 2 



lie North Broadway « ^ 



EOTANJCAL 



PREHISTORIC CALIFORNIA, 



( Continued from January Bulletin ) ' 



BY DR. LORENZO GORDIN YATES. 



After the destruction of the cretaceous sea of the interior, 

 barriers were left or formed which caused the fresh water to 

 cover -large areas of land. These lakes in connection with a 

 probable depression of the land in the interior, created a warm 

 and humid climate, suitable for the growth of tropical plants, 

 and it may be noted that, pf the nearly three hundred species 

 of tropical plants found fossil in the earlier Tertiary, a large 

 proportion were Palms, many of them of great size. All of 

 these with perhaps one exception (in San Diego county), have 

 since migrated, or become extinct, as well as many others 

 which will be referred to later on. 



The huge reptiles of the Cretaceous were replaced by Croco- 

 diles, Lizards, Snakes and Frogs, and the connecting links be- 

 tween the Reptiles and the Birds disappeared. Birds of all 

 kinds appear which show a tropical character. The late Pro- 

 fessor Cope, one of the most celebrated palaeontologists of the 

 time, described a gigantic ostrich-like bird, supposed to have been 

 twice the size of the present ostrich. 



The itrue mammals suddenly appeared in great numbers 

 during the time of the formation of the oldest Eocene beds'; 

 Small marsupials are known to have existed before the Cre- 

 taceous, but now the earth fairly swarmed with true mammals. 



This sudden appearance is supposed to have resulted from 

 a great rapidity of change of organic forms, "partly caused 

 by pressure of changed climate and partly from migration of 

 species, and the consequent struggle for life between different 

 geographical faunae." (LeConte.) 



A large number of species have been found fossil in the 

 Middle Eocene ; Professor O. C. Marsh found more than one 

 hundred and fifty species of vertebrates, including some Lemu- 

 rine Monkeys. 



This mammalian fauna was not continuous throughout the 

 Tertiary, but changed completely several times. 



