Animals and Plants of Past and Their Records 607 



fossilized plant resin (pine tree) which was originally soft and captured 

 the animal or plant intact. Later, the more volatile materials of the resin 

 disappeared, leaving the hard amber with its imprisoned organism. Cer- 

 tain organisms may leave their remains more or less intact by being 

 mired in quicksands or swamps. 



When the skeletal structure is preserved practically unchanged, it re- 

 mains almost in its original condition, except that it has lost most, if 

 not all, of its organic material. In this method of fossilization, only the 

 skeleton remains, while in the method described above, the skeleton and 



Fig. 314. — Beresovka mammoth {Elephas primigenius) discovered frozen in the 

 soil in Beresovka, Siberia, 800 miles west of Bering Strait and 60 miles north of 

 the Arctic Circle. Clotted blood, unswallowed grass, as well as the entire specimen 

 were quite well preserved by refrigeration. The specimen is shown as it appears in 

 the Petrograd Museum. (From Lull: Organic Evolution. By permission of The 

 Macmillan Company, publishers.) 



all Other structures as well are preserved. The author has found several 

 skeletons of ancient mastodons, more or less well preserved, in soils of 

 central and southwestern Ohio. In some instances the skeletal remains 

 may have added such chemicals as carbonate of lime, which makes them 

 more compact and heavier than the original. In other instances the 

 skell-like skeletons of ancient animals have become more porous and 

 somewhat lighter than they were originally. 



