IO THE COLLECTION OF FOSSIL VERTEBRATES 
East Wing. Hall No. 407. Fossil Reptiles, Amphibians and 
Fishes. 
In addition 
East Corridor, No. 405 (in which are the elevator and stair-> 
ways), contains fossil Marine Reptiles and Fishes of the Age of 
Reptiles. 
SKELETON OF THE GREAT MARINE LIZARD IN THE EAST CORRIDOR 
THE EAST CORRIDOR. No. 405. 
On stepping from the elevator the visitor sees before him a 
case filled with skulls and skeletons of the marine reptiles and 
The Preser- UShes which inhabited the great inland sea that once 
vation of | spread over the center of the North American conti- 
Fossilsin nent, from Canada to Mexico. The reptiles were of 
the Rocks. tinds now long extinct, Plesiosaurs with long snaky 
neck, short bulky body with long flippers and stubby tail, and 
Mosasaurs with short neck and longer tail. Some of the fishes 
were ancestors, collateral or direct, of certain modern fishes, 
others belonged to groups now extinct. These animals lived and 
died, their carcasses sank to the bottom of the sea, and were 
buried in whatever sediment was being deposited there—soft 
white ooze in the open sea, dark gray or black mud nearer the 
shores. In the course of ages this ooze or mud settled gradually 
and consolidated into chalk or shale. Afterwards as the conti- 
nent rose above the waters and assumed more nearly its present 
dimensions, the rivers flowing over the broad plains excavated 
