When the adventurous newts and frogs of that remote period
first dropped their gills and hopped about inquiringly on the dry land,
under the shadow of the ancient tree-ferns and club-mosses, they were
the only terrestrial vertebrates then existing, and they had the field
(or, rather, the forest) all to themselves. For a while, therefore, like
all dominant races for the time being, they blossomed forth at their
ease into relatively gigantic forms. Frogs as big as donkeys, and efts
as long as crocodiles, luxuriated to their hearts' content in the marshy
lowlands, and lorded it freely over the small creatures which they found
in undisturbed possession of the Carboniferous isles. But as ages passed
away, and new improvements were slowly invented and patented by survival
of the fittest in the offices of nature, their own more advanced and
developed descendants, the reptiles and mammals, got the upper hand
with them, and soon lived them down in the struggle for life, so that
this essentially intermediate form is now almost entirely restricted to
its one adapted seat, the pools and ditches that dry up in summer.
The reptiles, again, are a class in which the biggest modern forms are
simply nowhere beside the gigantic extinct species. First appearing on
the earth at the very close of the vast primary periods--in the Permian
age--they attained in secondary times the most colossal proportions, and
have certainly never since been exceeded in size by any later forms of
life in whatever direction.
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