"I cannot agree with this view--the animals _must_ have laid their eggs upon land--for the reason that reptile eggs cannot hatch in water. S.W.W." But with deference to Williston's high authority I may note that there is no evidence that the Sauropoda were egg-laying reptiles. They, or some of them, may have been viviparous like the Ichthyosaurus.] [Footnote 13: European palaeontologists, especially Huxley and Seeley in England, had also recognized their true relationships, and Seeley's term Cetiosauria has precedence over Sauropoda, although the latter is in common use.] [Footnote 14: It is of interest to observe that in this group of Sauropoda, the Brachiosauridae, the neural spines of the vertebrae are much simpler and narrower than in the Brontosaurus and Diplodocus. The attachments were thus less extensive for the muscles of the back, indicating that these muscles were less powerful. This difference is correlated by Professor Williston with the longer fore limbs of the Brachiosaurus, as signifying that the animal was less able, as indeed he had less need, to rise up upon the hind limbs, in comparison with Diplodocus or Brontosaurus in which the fore limbs were relatively short.] CHAPTER VI. THE BEAKED DINOSAURS. ORDER ORTHOPODA (ORNITHISCHIA OR PREDENTATA.) The peculiar feature of this group of Dinosaurs is the horny beak or bill. The bony core sutured to the front of the upper and lower jaws was covered in life by a horny sheath, as in birds or turtles. But this is not the only feature in which they came nearer to birds than do the other Dinosaurs. The pelvic or hip bones are much more bird-like in many respects, especially the backward direction of the pubic bone, the presence of a prepubis, in the number of vertebrae coossified into a solid sacrum, in the proportions of the ilium and so on. Various features in the anatomy of the head, shoulder-blades and hind limbs are equally suggestive of birds, and it seems probable that the earliest ancestors of the birds were very closely related to the ancestors of this group of Dinosaurs. But the ancestral birds became adapted to flying, the ancestral Predentates to terrestrial life, and in their later development became as widely diversified in form and habits as the warm-blooded quadrupeds which succeeded them in the Age of Mammals. [Illustration: Fig. 25.--Skulls of Iguanodont and Trachodont Dinosaurs. _Iguanodon_ and _Camptosaurus_ of the Jurassic and Comanchic; _Kritosaurus_ and _Corythosaurus_ of the Middle Cretacic (Belly River); _Saurolophus_ of the late Cretacic (Edmonton); _Trachodon_ of the latest Cretacic (Lance). The Iguanodon is European, the others North American. All 1/25 natural size.]