III. _Beaked Dinosaurs_ or _Predentates_. With a horny beak on the
front of the jaw, cutting or grinding teeth behind it. All
herbivorous, with pelvis of peculiar type, with hoofs instead of
claws, and many genera heavily armored. Mostly three short toes on the
hind foot, four or five on the fore foot. This group comprises animals
of very different proportions as follows:
1. _Iguanodonts._ Bipedal, unarmored, with a single row of serrated
cutting teeth, three-toed hind feet. Upper Jurassic, Comanchic and
Cretacic. _Camptosaurus_ is the best known American genus.
2. _Trachodonts_ or _Duck-billed Dinosaurs_. Like the Iguanodonts but
with numerous rows of small teeth set close together to form a
grinding surface. Cretacic period. _Trachodon, Hadrosaurus,
Claosaurus, Saurolophus, Corythosaurus, etc._
3. _Stegosaurs_ or _Armored Dinosaurs_. Quadrupedal dinosaurs with
elephantine feet, short neck, small head, body and tail armored with
massive bony plates and often with large bony spines. Teeth in a
single row, like those of Iguanodonts. _Stegosaurus_ of the Upper
Jurassic, _Ankylosaurus_ of the Upper Cretacic.
[Illustration: Fig. 8.--Hind Feet of Dinosaurs, to show the three
chief types (Theropoda, Orthopoda, Sauropoda).]
4. _Ceratopsian_ or _Horned Dinosaurs_. Quadrupedal with elephantine
feet, short neck, very large head enlarged by an enormous bony frill
covering the neck, with a pair of horns over the eyes and a single
horn in front.
Pages:
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30