136 
EXTINCT MONSTERS 
mouse. Then the sabre-like teeth would be brought into action 
by the powerful jaws, and soon the flesh and bones of the victim 
would be gone ! 
As we remarked before, the carnivorous Dinosaurs were the 
lions and tigers of the Mesozoic era, and, what with small 
mammals and numerous reptiles of those days, it would seem 
that they were not limited in their choice of diet. 
During the early part of the Mesozoic era, at the period known 
as the Triassic (New Red Sandstone), Dinosaurs flourished 
vigorously in America, developing a great variety of forms and 
sizes. Although but few of their bones have as yet been dis- 
covered in those rocks, they have left behind unmistakable 
evidence of their presence in the well-known footprints and other 
impressions upon the shores of the waters which they frequented 
(see p. 48). 
The late Professor Marsh had the good fortune to discover a 
very peculiar new form of carnivorous Dinosaur, to which he 
gave the name Ceratosaurus,^ because its skull supported a 
horn. But the horn is not the only feature presented by this 
interesting creature. Its vertebrae are of a strange and un- 
expected type ; and in the pelvis all the bones are fused together, 
as in modern birds. Externally, also, the Ceratosaurus differed 
from other members of the carnivorous group, for its body was 
partly protected by long plates in the skin, such as crocodiles 
have : these extended from the back of the head, along the neck, 
and over the back. An almost complete skeleton was found 
which indicates an animal about twenty-two feet long. When 
alive it was probably about half the bulk of the Allosaurus 
mentioned above. (See Eig. 44.) 
1 Greek — heras^ horn ; sauros, lizard. Some authorities consider it to be 
identical with Megalosaurus. 
