"
[Illustration: Fig. 155.--Supposed footprint of a Bird, from
the Triassic Sandstones of the Connecticut River. The slab shows
also numerous "rain-prints."]
Lastly, we find in the Triassic rocks the remains of Reptiles
belonging to the great Mesozoic order of the _Deinosauria_. This
order attains its maximum at a later period, and will be spoken of
when the Jurassic and Cretaceous deposits come to be considered.
The chief interest of the Triassic Reptiles of this group arises
from the fact that they are known by their footprints as well as
by their bones; and a question has arisen whether the supposed
footprints of _birds_ which occur in the Trias have not really
been produced by Deinosaurs. This leads us, therefore, to speak
at the same time as to the evidence which we have of the existence
of the class of Birds during the Triassic period. No actual bones
of any bird have as yet been detected in any Triassic deposit;
but we have tolerably clear evidence of their existence at this
time in the form of _footprints_. The impressions in question
are found in considerable numbers in certain red sandstones of
the age of the Trias in the valley of the Connecticut River, in
the United States. They vary much in size, and have evidently been
produced by many different animals walking over long stretches of
estuarine mud and sand exposed at low water.
Pages:
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341