This would allow of a northward migration
of such terrestrial animals during the summer-time, when there
would be an ample supply of food and a suitably high temperature,
and a southward recession towards the approach of winter.
The chief palaeontological interests of the Pliocene deposits,
as of the succeeding Post-Pliocene, centre round the Mammals of
the period; and amongst the many forms of these we may restrict
our attention to the orders of the Hoofed Quadrupeds (_Ungulates_),
the _Proboscideans_, the _Carnivora_, and the _Quadrumana_. Almost
all the other Mammalian orders are more or less fully represented
in Pliocene times, but none of them attains any special interest
till we enter upon the Post-Pliocene.
Amongst the Odd-toed Ungulates, in addition to the remains of
true Tapirs (_Tapirus Arvernensis_), we meet with the bones of
several species of Rhinoceros, of which the _Rhinoceros Etruscus_
and _R. Megarhinus_ (fig. 249) are the most important. The former
of these (fig. 249, A) derives its specific name from its abundance
in the Pliocene deposits of the Val d'Arno, near Florence, and
though principally Pliocene in its distribution, it survived
into the earlier portion of the Post-Pliocene period. _Rhinoceros
Etruscus_ agreed with the existing African forms in having two
horns placed one behind the other, the front one being the longest;
but it was comparatively slight and slender in its build, whilst
the nostrils were separated by an incomplete bony partition.
Pages:
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487