[Illustration: Fig. 46.--Badlands on the Red Deer River in
Alberta. This region is the richest known collecting ground for
cretacic dinosaurs.]
There is an entirely different class of explanations, however, to be
considered, which are consistent both with the continued fitness of
structure of the giant dinosaurs themselves and with the survival of
their especial food; such, for example, as the introduction of a _new
enemy_ more deadly even than the great carnivorous dinosaurs. Among
such theories the most ingenious is that of the late Professor Cope,
who suggested that some of the small, inoffensive, and inconspicuous
forms of Jurassic mammals, of the size of the shrew and the hedgehog,
contracted the habit of seeking out the nests of these dinosaurs,
gnawing through the shells of their eggs, and thus destroying the
young. The appearance, or evolution, of any egg-destroying animals,
whether reptiles or mammals, which could attack this great race at
such a defenseless point would be rapidly followed by its extinction.
We must accordingly be on the alert for all possible theories of
extinction; and these theories themselves will fall under the
universal principle of the survival of the fittest until we
approximate or actually hit upon the truth.
FOSSIL HUNTING BY BOAT IN CANADA.
_By Barnum Brown._
"How do you know where to look for fossils?" is a common question. In
general it may be answered that the surface of North America has been
pretty well explored by government surveys and scientific expeditions
and the geologic age of the larger areas determined.
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