sloping banks of a muddy estuary or of a
lagoon, either bare tidal flats or covered with vegetation. Evidently
the dinosaurs were buried at or near the spot where they perished.

The Bone-Cabin Quarry deposit represents entirely different
conditions. The theory that it is the accumulation of a flood is, in
my opinion, improbable, because a flood would tend to bring entire
skeletons down together, distribute them widely, and bury them
rapidly. A more likely theory is that this was the area of an old
river-bar, which in its shallow waters arrested the more or less
decomposed and scattered carcasses which had slowly drifted
down-stream toward it, including a great variety of dinosaurs,
crocodiles, and turtles, collected from many points up-stream. Thus
were brought together the animals of a whole region, a fact which
vastly enhances the interest of this deposit.

_The Giant Herbivorous Dinosaurs._ By far the most imposing of these
animals are those which may be popularly designated as the great or
giant dinosaurs. The name, derived from _deinos_ terrible, and
_sauros_ lizard, refers to the fact that they appeared externally like
enormous lizards, with very long limbs, necks, and tails. They were
actually remotely related to the tuatera lizard of New Zealand, and
still more remotely to the true lizards.

No land animals have ever approached these giant dinosaurs in size,
and naturally the first point of interest is the architecture of the
skeleton. The backbone is indeed a marvel. The fitness of the
construction consists, like that of the American truss-bridge, in
attaining the maximum of strength with the minimum of weight. It is
brought about by dispensing with every cubic millimeter of bone which
can be spared without weakening the vertebrae for the various stresses
and strains to which they were subjected, and these must have been
tremendous in an animal from sixty to seventy feet in length. The
bodies of the vertebrae are of hour-glass shape, with great lateral and
interior cavities; the arches are constructed on the T-iron principle
of the modern bridge-builder, the back spines are tubular, the
interior is spongy, these devices being employed in great variety, and
constituting a mechanical triumph of size, lightness, and strength
combined. Comparing a great chambered dinosaurian (_Camarasaurus_)
vertebra (see above) with the weight per cubic inch of an ostrich
vertebra, we reach the astonishing conclusion that it