FOSSIL PLUMAGE. 



C. R. EASTMAN. 



Preservation of avian remains in the fossil state is neces- 

 sarily of very rare occurrence, and extraordinarily so, if fossiliza- 

 tion takes place in marine sediments. Cases of the latter 

 description presuppose the creature either to have i^erished at 

 sea, or to have been swept out at a distance from the land as a 

 floating carcass without having been destroyed by predaceous 

 animals. The body must have sunk to the bottom before decom- 

 position had advanced far enough to disrupt the skeleton and 

 scatter the plumage. Burial by fine sediments must have fol- 

 lowed almost immediately, in order that the body be preserved 

 intact. And mineral replacenient of the organic tissues must 

 have proceeded in a wonderfully subtle manner, transforming 

 the most delicate particles into stone without obliterating their 

 microscopic structure. 



Supposing a dead bird to have reached the bottom in a toler- 

 ably complete condition, the feathers naturally become loosened 

 and scattered with decomposition of the skin, and the least cur- 

 rent is liable to sweep them away except they become entangled 

 and covered by the sediment at once. If the material happens 

 to be a fine calcareous ooze, the feathers may leave in it an 

 exceedingly delicate impression, or, in the rarest cases of all, 

 their structure may become replaced molecule for molecule by 

 mineral matter, generally calcareous or carbonaceous. 



Chance, controlling thus absolutely the tatc ot this ( las.s of 

 remains, goes away after sealing them up in the locks to u-niain 

 hidden for ages; but may peradventure come bcuk a-aiu, and 

 disclosing them to the light of day, permit them to fall into 

 the domain of scientific investigation, (jreat as is the miracle, 

 it has actually happened a few times, as witness the two 

 complete individuals of Archzeopteryx that are known, and one 

 of Hesperornis, with their plumage preserved. Scarcely less 

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