No. 381.] A HALF-CENTURY OF EVOLUTION. 667 
Tertiary the great mountain ranges of Asia and Europe, the 
Alps, Pyrenees, Caucasus, Himalayas, as well as the Atlas, 
and the Cordillera of North and South America were upheaved. 
The old Tertiary nummulitic beds were, in the western Alps, 
_ raised to a height of 11,000 feet, and the Himalayas to a hori- 
zon 16,000 feet above the sea, while there were correspond- 
ing elevations in western North America and in the Rocky 
Mountain region. 
The evidence from fossils shows, what has not been disputed, 
that climatic zones were by this time established. In Europe 
the older Tertiary was decidedly tropical, in the Miocene sub- 
tropical, but the climate of Europe was somewhat lowered late 
in the Miocene, as shown by the absence of palms.! At the 
end of the Tertiary, z.e., during the Pliocene, the earth’s climate 
was but slightly warmer than at present. It should be here 
noticed that while Greenland, Iceland, Spitzbergen, and Grin- 
nell Land under 81° north latitude were during the late Ter- 
tiary “abnormally warm,” the Tertiary floras of northeastern 
1 Jaeger suggests that the occurrence in the later geological periods of warm- 
blooded vertebrates, protected by feathers or hair, was due to the fact that the 
earth then became cooler than in the preceding ages. His explanation of the ori- 
gin of feathers and hair is as follows: “If the average temperature of an animal 
body is considerably higher than that of the surrounding rene oscillations of 
these media have a stimulating effect upon the skin of the an This leads to 
a tendency to form papillary chorian Wi cells, and these poe na produce hair 
or feathers, which BARE two of the most characteristic features of warm- 
blooded animals.” He adds that this “ BSE effect upon the skin can only 
be due to low temperatures.” yer body temperature of the birds and mammals 
being high, and the covering of the hair or feathers rendering them proof against 
the extremes of heat and cold, we can see that there is a coincidence between this 
and the fact that these classes began to increase in numbers towards the end of 
the Mesozoic, and es especially at the opening of the Tertiary, when the climatic 
zones began to be established. So also in the case of whales the loss of 
compensated for by the blubber. Why, however, feathers developed in vs rds, 
rather than hair, is a problem no one has attempted to solve; though feathers of 
course better adapt the bird for flight ; no flightless birds Agee ss well-devel- 
oped feathers as those capable of extended flight , Problems of 
Nature, translated by Henry G. Schlichter, D. S. C., p. 66 1897. 
t might be suggested that the broad, vane-like surface RPE characterizes 
feathers as compared with hairs may have been due to the fact that they would 
better support the body in flight; this difference from scales, as well as their 
greater lightness, giving this sort of armature an advantage over scales on the one 
hand and hairs on the other. 
