er found; this is the
_Brachiosaurus_, limb-bones of which were discovered in central
Colorado in 1901 and are now preserved in the Field Columbian Museum
of Chicago. Its thigh-bone is six feet eight inches in length, and its
upper arm-bone, or humerus, is even slightly longer.

_Feeding Habits of the Giant Dinosaurs._ We still have to solve one of
the most perplexing problems of fossil physiology; how did the very
small head, provided with light jaws, slender and spoon-shaped teeth
confined to the anterior region, suffice to provide food for these
monsters? I have advanced the idea that the food of _Diplodocus_
consisted of some very abundant and nutritious species of water-plant;
that the clawed feet were used in uprooting such plants, while the
delicate anterior teeth were employed only for drawing them out of the
water; that the plants were drawn down the throat in large quantities
without mastication, since there were no grinding or back teeth
whatever in this animal. Unfortunately for this theory, it is now
found that the front feet were not provided with many claws, there
being only a single claw on the inner side. Nevertheless by some such
means as this, these enormous animals could have obtained sufficient
food in the water to support their great bulk.

_The Carnivorous Dinosaurs._ Mingling with the larger bones in the
quarry are the more or less perfect remains of swamp turtles, of dwarf
crocodiles, of the entirely different group of plated dinosaurs, or
_Stegosauria_, but especially of two entirely distinct kinds of large
and small flesh-eating dinosaurs. The latter rounded out and gave
variety to the dinosaur society, and there is no doubt that they
served the savage but useful purpose, rendered familiar by the
doctrine of Malthus, of checking overpopulation. These fierce animals
had the same remote ancestry as the giant dinosaurs, but had gradually
acquired entirely different habits and appearance.

Far inferior in size, they were superior in agility, exclusively
bipedal, with very long, powerful hind limbs, upon which they advanced
by running or springing, and with short fore limbs, the exact uses of
which are difficult to ascertain. Both hands and feet were provided
with powerful tearing claws. On the hind foot is the back claw, so
characteristic of the birds, which during the Triassic period left its
faint impression almost everywhere in the famous Connecticut valley
imprints of these animals. That th