
WEST 



AN 
INVERTEBRATE: 
AL GEOL 


| 
PHILIPPINE ISLANDS 
HISTORIC 
FOSS 



COLLECTIONS 
FROM 
SOUTH SEA 
ISLANDS 









A Se a jal EY ag ie 
OSSIL MAMMALS 
DINOSAUR 5S) 
(MAS TODONS) 
MINERALS 




Elevators 
2. Fossil Fishes 
FOURTH FLOOR 
FOREWORD ON Fosstn VERTEBRATES 
In the East Corridor, and the South Pavilion at the left, as well as in 
the East 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 be- 
come 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 silicate. 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 accumu- 
late 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 de- 
termining the age of the earth and the succession of life thereon. Nearly 
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