THE BIGGEST BEAST
There is a prevalent notion, encouraged by the fanciful exaggerations
of newspaper gossips, that the animals of past ages, whose bones are
from time to time dug out of rocks and sand quarries, were many of
them much bigger than any at present existing, and that we are living
in an age of degeneracy. It is true that the mammoth and the mastodon
were enormous creatures, but they were _not_ bigger than their living
representatives, the great elephants of Africa and India. The African
elephant often stands 11 ft. high at the shoulder, and occasionally
attains 12 ft.
Some eighty years ago Dr. Gideon Mantell became celebrated by his
discovery of the bones of huge reptiles–far bigger than any existing
crocodile or lizard–nearly as big as elephants, in the Wealden rocks of
Tilgate Forest in Sussex. He and Sir Richard Owen distinguished several
kinds–the Iguanodon, the Megalosaurus, the Hylæosaurus, and others.
Models of these creatures as they appeared when clothed in flesh and
hide were carefully made, and placed picturesquely among the ponds and
islands of the gardens of the Crystal Palace at Sydenham when it was
first opened to an enchanted public in the fifties. As a small boy I,
at that time, fell under their spell.
The passing years have brought to us more complete knowledge of these
strange beasts–now classed as the "Dinosauria"–and new kinds and
complete skeletons of those already known have been discovered in the
United States and in Belgium. The leg bones and vertebræ of one of
the biggest were found near Oxford, and are in the Oxford Museum; it
received the name Cetiosaurus. Only a few years ago a very complete
skeleton of a creature closely allied to Cetiosaurus was with great
labour and skill dug out of the Jurassic rocks of Wyoming, U.S.A., by
Dr. Holland, at the charges of Mr. Andrew Carnegie. It was known as
Diplodocus (referring to certain bones in its tail), and a wonderful
cast of the completely reconstructed skeleton was presented to the
Natural History Museum in London, when I was Director, by Mr. Carnegie.
The skeleton is 84 ft. long; but we must not be mis-led as to the
animal's actual bulk by this measurement, for the tail is 46 ft. long
and whip-like, whilst the neck is 23 ft. long and carries a small head
not bigger than that of a cart-horse. The jaws were provided with
small peg-like teeth, showing that the beast fed on soft vegetable
matter. The body, apart from neck and tail, was really only a little
bigger than that of a large elephant, and the limb-bones longer in
the proportion of about six to five. Another reptile very similar to
these and also found in the mesozoic rocks of the U.S. America is
Brontosaurus.
The fact is that, if we wish to make an intelligent comparison of
the sizes of different animals, we have carefully to ascertain not
merely the length measurements, but the _proportions_ of the various
parts, and the actual bulk and probable weight of the beasts under
consideration. Also (and this is a very important and decisive matter)
we must know whether the beasts were terrestrial in habit, walking with
their bodies raised high on their legs, or whether they were aquatic
and swam in the lakes or seas, their bodies buoyed up and supported by
the water. By far the biggest animals of which we have any knowledge
are the various kinds of whales still flourishing in the sea. A
mechanical limit is set to the size of land-walking animals, and that
limit has been reached by the elephant "Flesh and blood," and we may
add "bone," cannot carry on dry land a greater bulk than his. He is
always in danger of sinking by his own weight into soft earth and bog.
His legs have to be much thicker in proportion than those of smaller
animals–made of the same material–or they would bend and snap. His feet
have to be padded with huge discs of fat and fibre to ease the local
pressure, and his legs are kept straight not bent at the joints, when
he stands (a fact to which Shakespeare makes Ulysses refer), so that
the vast weight of his body shall be supported by the stiff column
formed by the upper and lower half of the limb-bones kept upright in
one straight line. A well-grown elephant weighs five tons. Compare his
weight and shape with that of a big whale-bone whale! No extinct animal
known approaches the existing whale in bulk and weight. He is 80 to
90 ft. long, and has no neck nor any length of tail. His outline is
egg-like, narrower at the hinder end. He weighs 200 tons–forty times as
much as a big elephant–and is perfectly supported without any strain on
his structure by the water in which he floats. There is no such limit
to his possible size as there is in the case of land-walking animals.
But it seems probable that he too is limited in size by mechanical
conditions of another kind. Probably he cannot exceed some 90 ft. in
length and 200 tons of bulk on account of the relatively great increase
of proportionate size and power in the heart required in order to
propel the blood through such a vast mass of living tissue and keep
him "going" as a warm-blooded mammal. The original pattern–the small
dog-like ancestor of the whale–cannot be indefinitely expanded as an
efficient working machine, though its limit of growth is not determined
by the same mechanical causes as those which limit the bulk of the
terrestrial quadruped.
These considerations make it clear that we should compare as to
"bigness" terrestrial animals with other terrestrial animals, and
aquatic animals with aquatic ones. It seems probable that Diplodocus
was an aquatic reptile, and never raised himself on to his four legs
on dry land as the Carnegie skeleton at the Natural History Museum is
doing. His legs and feet are quite unfitted to support his weight on a
land surface; on land he would have rested on his belly, as a crocodile
does, with much bent legs on each side. But submerged in 20 ft.
depth of water, he could have trotted along, half-floating, with his
feet touching the bottom and his head raised on its long neck to the
surface, slowly sucking the floating vegetation into his moderate-sized
mouth. (See drawing on p. 91.)
Diplodocus and Cetiosaurus have huge thigh-bones and upper-arm
bones–respectively 5 ft. 9 in. and 3 ft. 2 in. in length–until lately
the biggest known _limb_-bones, although the lower jaw-bone of a Right
Whale grows to be 18 ft. in length. But a thigh-bone (femur) of a
reptile similar to Diplodocus has been found in Wyoming, 6 ft. 2 in.
in length. This reptile was named Atlantosaurus, and a cast of the
huge bone–the biggest known when it was placed there–stands in our
museum gallery. However, its glory has departed, for we now know "than
this biggest bone, a bigger still." The bones of several individuals
of a huge reptile similar to Diplodocus, but actually twice as big in
linear dimensions, were found by Dr. Fraas at Tendagoroo, fifty miles
from the coast in German East Africa, and brought safely to Berlin in
1912, though they have not yet been mounted as a complete specimen.
They were lying in a sandy deposit of the same geologic age as our
Sussex Wealden. A special expedition of 500 negroes was sent–not by
the Government, but by the Berlin "Society of the Friends of Natural
History" (we need such a society in England), at a cost of £10,000,
to fetch the bones. They were of many individuals, and had to be
skilfully dug out and packed. Dr. Fraas calls this biggest of all
quadrupeds "Gigantosaurus." A cast of the humerus, or upper-arm bone,
is now exhibited in the Natural History Museum. It is over 7 ft. in
length. The femur, or thigh-bone, was still bigger–it was over 10 ft.
in length. Alas for the glory of Atlantosaurus! This enormous creature
was, of course, like Diplodocus, aquatic. Its bulk was much less than
that of a big whale, but extinct aquatic reptiles may yet be found of
greater size. Ichthyosaurus, the extinct whale-like reptile, does not
exceed 30 ft. in length. Our engraving (Fig. 32) shows the relative
size of the humerus of man, the elephant,[4] and the Gigantosaurus. How
puny is that human arm-bone! And yet...!
When stretched on the shore, resting on the belly, the body of the
great lizard of Tendagoroo bulked like a breakwater 12 ft. high, and
his tail like a huge serpent extended 80 ft. beyond it; whilst his head
and neck reached 40 ft. along the mud in front.
[Illustration: FIG. 32.–The upper-arm bone or humerus of the great
reptile (Gigantosaurus) of Tendagoroo–compared with that of man and of
an Indian elephant.]
An important limitation to great size in an animal is, it must be
remembered, often imposed by the nature of the animal's food. Ten
individuals each weighing a hundredweight will more easily pick up
and swallow the amount of food required to nourish ten hundredweight
of the species than will one individual responsible for the whole
bulk, provided that the food is scattered and not ready to the mouth
in unlimited quantity. A creature which has unlimited forest or grass
or seaweed as its food will be at no disadvantage owing to its size.
But a carnivor or a fish-eater or one depending on special fruits and
roots not offered to him by nature in mass has to search for, and
sometimes to hunt, or at any rate to compete with others, for the
scattered and elusive "bits" of food. So it is that we find that the
fruit-eating apes are not very big, and that terrestrial carnivors are
small, though powerful and swift, as compared with cattle, deer, and
vegetarian beasts. Ten carnivors weighing each ten stone will with
their ten mouths "pick up" more prey than one carnivor weighing a
hundred stone and having only one mouth. Even the carnivorous Dinosaurs
such as Megalosaurus and Tyrannosaurus were much smaller than the
vegetarian Iguanodon, Diplodocus, Brontosaurus and Triceratops on
which (or on the like of which) they preyed–just as a tiger is smaller
than a buffalo, and a wolf smaller than a horse. It is owing to causes
of this nature that the life of some animals, and consequently their
growth, is limited in duration. Occasionally the common lobster lives
to a great age, and grows to be more than 2 ft. long. But he is doomed
by his size; the smaller lobsters "go quickly around" and get all
the food (carrion of the sea), and the big fellow has to starve. The
whale-bone whales, it is true, take animal food; but it occurs in the
form of minute sea-slugs and shrimps, which fill the surface waters in
countless millions over hundreds of miles of ocean. Hence the whales of
this kind have only to swim along with their mouths open through an
unlimited supply of luscious food. The size of terrestrial animals is
also, it appears, definitely related to the natural water-supply. There
are very few small quadrupeds in the interior of Africa. On account of
frequent "drought," the mammals have often to run a hundred miles or
more in search of water. Only animals as big as the larger antelopes
and the zebra can cover the ground. The smaller kinds die (and have, in
fact, died out in past ages) in these regions of sudden drought.
[Illustration: The gigantic reptile Diplodocus on land.]
FOOTNOTE:
[4] The elephant, the thigh-bone of which, measuring nearly 3 ft. in
length, is drawn in Fig. 32, is a large Indian one. This species is
exceeded in size by the African. See "Science from an Easy Chair,"
Second series, p. 123.–The largest elephant the bones of which are
known is the Elephas antiquus of the Pleistocene, bigger than either of
the living species and bigger than the mammoth, Elephas primigenius.
The arm-bone (humerus) of one of this species (Elephas antiquus) lately
dug up near Chatham and now in the Natural History Museum, is 4 ft. 3
in. in length.