CHAPTER V.
THE AMPHIBIOUS DINOSAURS, BRONTOSAURUS, DIPLODOCUS, ETC.
SUB-ORDER OPISTHOCOELIA (CETIOSAURIA OR SAUROPODA).
These were the Giant Reptiles par-excellence, for all of them were of enormous size, and some were by far the largest of all four-footed animals, exceeded in bulk only by the modern whales.

In contrast to the carnivorous dinosaurs these are quadrupedal, with very small head, blunt teeth, long giraffe-like neck, elephantine body and limbs, long massive tail prolonged at the tip into a whip-lash as in the lizards.
Like the elephant they have five short toes on each foot, probably buried in life in a large soft pad, but the inner digits bear large claws, blunt like those of turtles, one in the fore foot, three in the hind foot.
To this group belong the Brontosaurus and Diplodocus, the Camarasaurus, Morosaurus and other less known kinds.

All of them lived during the late Jurassic and Comanchic ("Lower Cretaceous") and belong to the older of the two principal Dinosaur faunas.

They were contemporaries of the Allosaurus and Megalosaurus, the Stegosaurus and Iguanodon, but unlike the Carnivorous and Beaked Dinosaurs they became wholly extinct before the Upper or true Cretacic, and left no relatives to take part in the final epoch of expansion and prosperity of the dinosaurian race at the close of the Reptilian era.
[Illustration: Fig.

20 .-- Skeletons of _Brontosaurus_ (above) and _Diplodocus_ (below) in the American Museum.