NORTH 






Li aid 
weEstT EAST 
COR 
PHILIPPINE ISLANDS 
LUM ING = TR BE S 
FOSSIL INVERTEBRATES 
HISTORICAL GEOLOGY 





COLLECTIONS 
FROM 


FOSSIL 
REPTILES 
SUES (DINOSAURS) 




MINERALS OSSit MAMMALS 
ane (Mas TODONS) 
ISLANDS 

1. Elevators 
2. Fossil Fishes 

FourtTH FLoor 
FOREWORD ON FOSSIL VERTEBRATES 
In the East Corridor, and the South Pavilion at the left, as well as in 
the Hast Wing and Southeast Pavilion at the right, are displayed the fossil 
mammals, reptiles, and fishes. 
In a general way, fossils are the petrified remains of plants or animals 
that lived at some past period of the earth’s history. In many instances 
we have not the objects themselves, but only their casts or impressions in 
the rocks. This is particularly the case with shells. Sometimes, as with 
the bones of the great Irish elk, the objects have been buried in swamps or 
bogs, and in a few rare instances, as with the mammoth and woolly 
rhinoceros, entire animals have been preserved for thousands of years 
in ice or frozen mud. Fossils are found in localities where the dead 
animals or plants have gradually been buried under layers of sediment 
to such a depth that they come in contact with the mineral waters of the 
earth and finally become petrified. Later through subsequent upheaval 
and erosion they are again brought to or near the surface of the earth. 
Petrifaction is the slow replacement of animal or vegetable material 
by such minerals as carbonate of lime or silica. The process is very 
slow and for this reason flesh is never petrified. Fossil beds are found 
in every continent. In our own country, Texas, Montana, Wyoming, 
and the Bad Lands of South Dakota are famous for their large fossil 
beds, and many of the finest and rarest fossils in the Museum were 
obtained in these localities. 
As it takes thousands of years for the various layers of earth to 
accumulate over the bones, and for the latter to become petrified, the 
study of fossils and the strata in which they are found is an important 
aid in determining the age of the earth and the succession of life thereon. 
96 
