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THE AGE OF REPTILES
We find both these groups, in patriarchal forms, in Europe, North
America, and South Africa during the Permian period. They are
usually moderate in size, but in places they seem to have found
good conditions and prospered. A few years ago a Permian bed in
Russia yielded a most interesting series of remains of Synapsid
reptiles. Some of them were large vegetarian animals, more than
twelve feet in length; others were carnivores with very powerful
heads and teeth as formidable as those of the tiger. Another
branch of the same order lived on the southern continent,
Gondwana Land, and has left numerous remains in South Africa. We
shall see that they are connected by many authorities with the
origin of the mammals.* The other branch, the Diapsids, are
represented to-day by the curiously primitive lizard of New
Zealand, the tuatara (Sphenodon, or Hatteria), of which I have
seen specimens, nearly two feet in length, that one did not care
to approach too closely. The Diapsids are chiefly interesting,
however, as the reputed ancestOrs of the colossal reptiles of the
Jurassic age and the birds.
* These Synapsid reptiles are more commonly known as Pareiasauria
or Theromorpha.
The purified air of the Permian world favoured the reptiles'
being lung-breathers, but the cold would check their expansion
for a time. The reptile, it is important to remember' usually
leaves its eggs to be hatched by the natural warmth of the
ground. But as the cold of the Permian yielded to a genial
climate and rich vegetation in the course of the Triassic, the
reptiles entered upon their memorable development. The amphibia
were now definitely ousted from their position of dominance. The
increase of the waters had at first favoured them, and we find
more than twenty genera, and some very large individuals, of the
amphibia in the Triassic. One of them, the Mastodonsaurus, had a
head three feet long and two feet wide. But the spread of the
reptiles checked them, and they shrank rapidly into the poor and
defenceless tribe which we find them in nature to-day.
To follow the prolific expansion of the reptiles in the
semi-tropical conditions of the Jurassic age is a task that even
the highest authorities approach with great diffidence. Science
is not yet wholly agreed in the classification of the vast
numbers of remains which the Mesozoic rocks have yielded, and the
affinities of the various groups are very uncertain. We cannot be
content, however, merely to throw on the screen, as it were, a
few of the more quaint and monstrous types out of the teeming
Mesozoic population, and describe their proportions and
peculiarities. They fall into natural and intelligible groups or
orders, and their features are closely related to the differing
regions of the Jurassic world. While, therefore, we must abstain
from drawing up settled genealogical trees, we may, as we review
in succession the monsters of the land, the waters, and the air,
glance at the most recent and substantial conjectures of
scientific men as to their origin and connections.
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