laid it, for a large bird may lay a small egg, or a small bird a large
one. Comparing the egg of the great Moa with that of our AEpyornis one
might think the latter much the larger bird, say twelve feet in height,
when the facts in the case are that while there was no great difference
in the weight of the two, that difference, and a superiority of at least
two feet in height, are in favor of the bird that laid the smaller egg.
The record of large eggs, however, belongs to the Apteryx, a New Zealand
bird smaller than a hen, though distantly related to the Moas, which
lays an egg about one-third of its own weight, measuring 3 by 5 inches;
perhaps it is not to be wondered at that the bird lays but two.
Although most of the eggs of these big birds that have been found have
literally been unearthed from the muck of swamps, now and then one comes
to light in a more interesting manner as, for example, when a perfect
egg of AEpyornis was found afloat after a hurricane, bobbing serenely up
and down with the waves near St. Augustine's Bay, or when an egg of the
Moa was exhumed from an ancient Maori grave, where for years it had lain
unharmed, safely clasped between the skeleton fingers of the occupant.
So far very few of these huge eggs have made their way to this country,
and the only egg of AEpyornis now on this side of the water is the
property of a private individual.
Most recent in point of discovery, but oldest in point of time, are the
giant birds from Patagonia, which are burdened with the name of
Phororhacidae, a name that originated in an error, although the error may
well be excused. The first fragment of one of these great birds to come
to light was a portion of the lower jaw, and this was so massive, so
un-bird-like, that the finder dubbed it _Phororhacos_, and so it must
remain.
[Illustration: Fig. 29.--Eggs of Feathered Giants, AEpyornis, Ostrich,
Moa, Compared with a Hen's Egg.]
It is a pity that all the large names were used up before this group of
birds was discovered, and it is particularly unfortunate that Dinornis,
terrible bird, was applied to the root-eating Moas, for these Patagonian
birds, with their massive limbs, huge heads and hooked beaks, were truly
worthy of such a name; and although in nowise related to the eagles,
they may in habit have been terrestrial birds of prey. Not all the
members of this family are giants, for as in other groups, some are big
and some little, but the largest among them might be styled the Daniel
Lambert of the feathered race. _Brontornis_, for example, the thunder
bird, or as the irreverent translate it, the thundering big bird, had
leg-bones larger than those of an ox, the drumstick measuring 30 inches
in length by 2-1/2 inches in diameter, or 4-1/4 inches across the ends,
while the tarsus, or lower bone of the leg to which the toes are
attached, was 16-1/2 inches long and 5-1/2 inches wide where the toes
join on. Bear this in mind the next time you see a large turkey, or
compare these bones with those of an ostrich: but lest you may forget,
it may be said that the same bone of a fourteen-pound turkey is 5-1/2
inches long, and one inch wide at either end, while that of an ostrich
measures 19 inches long and 2 inches across the toes, or 3 at the upper
end.
If Brontornis was a heavy-limbed bird, he was not without near rivals
among the Moas, while the great Phororhacos, one of his contemporaries,
was not only nearly as large, but quite unique in build. Imagine a bird
seven or eight feet in height from the sole of his big, sharp-clawed
feet, to the top of his huge head, poise this head on a neck as thick as
that of a horse, arm it with a beak as sharp as an icepick and almost as
formidable, and you have a fair idea of this feathered giant of the
ancient pampas. The head indeed was truly colossal for that of a bird,
measuring 23 inches in length by 7 in depth, while that of the racehorse
Lexington, and he was a good-sized horse, measures 22 inches long by
5-1/2 inches deep. The depth of the jaw is omitted because we wish to
make as good a case as possible for the bird, and the jaw of a horse is
so deep as to give him an undue advantage in that respect.
[Illustration: Fig. 30.--Skull of Phororhacos Compared with that of the
Race-horse Lexington.]
We can only speculate on the food of these great birds, and for aught we
know to the contrary they may have caught fish, fed upon carrion, or
used their powerful feet and huge beaks for grubbing roots; but if they
were not more or less carnivorous, preying upon such reptiles, mammals
and other birds as came within reach, then nature apparently made a
mistake in giving them such a formidable equipment of beak and claw. So
far as habits go we might be justified in calling them cursorial birds
of prey.
[Illustration: Fig. 31.--Leg of a Horse Compared with that of the Giant
Moa.]
We really know very little about these Patagonian giants, but they are
interesting not only from their great size and astounding skulls, but
because of the early age (Miocene) at which they lived and because in
spite of their bulk they are in nowise related to the ostriches, but
belong near the heron family. As usual, we have no idea why they became
extinct, but in this instance man is guiltless, for they lived and died
long before he made his appearance, and the ever-convenient hypothesis
"change of climate" may be responsible for their disappearance.
Something, perhaps, remains to be said concerning the causes which seem
to have led to the development of these giant birds, as well as the
reasons for their flightless condition and peculiar distribution, for it
will be noticed that, with the exception of the African and South
American ostriches the great flightless birds as a rule are, and were,
confined to uninhabited or sparsely populated islands, and this is
equally true of the many small, but equally flightless birds. It is a
seemingly harsh law of nature that all living beings shall live in a
more or less active struggle with each other and with their
surroundings, and that those creatures which possess some slight
advantage over their fellows in the matter of speed, or strength, or
ability to adapt themselves to surrounding conditions, shall prosper at
the expense of the others. In the power of flight, birds have a great
safeguard against changes of climate with their accompanying variations
in the supply of food, and, to a lesser extent, against their various
enemies, including man. This power of flight, acquired early in their
geological history, has enabled birds to spread over the length and
breadth of the globe as no other group of animals has done, and to
thrive under the most varying conditions, and it would seem that if this
power were lost it must sooner or later work harm. Now to-day we find no
great wingless birds in thickly populated regions, or where beasts of
prey abound; the ostriches roam the desert wastes of Arabia, Africa and
South America where men are few and savage beasts scarce, and against
these is placed a fleetness of foot inherited from ancestors who
acquired it before man was. The heavy cassowaries dwell in the thinly
inhabited, thickly wooded islands of Malaysia, where again there are no
large carnivores and where the dense vegetation is some safeguard
against man; the emu comes from the Australian plains, where also there
are no four-footed enemies[11] and where his ancestors dwelt in peace
before the advent of man. And the same things are true of the Moas, the
AEpyornithes, the flightless birds of Patagonia, the recent dodo of
Mauritius and the solitaire of Rodriguez, each and all of which
flourished in places where there were no men and practically no other
enemies. Hence we deduce that absence of enemies is the prime factor in
the existence of flightless birds,[12] although presence of food is an
essential, while isolation, or restriction to a limited area, plays an
important part by keeping together those birds, or that race of birds,
whose members show a tendency to disuse their wings. It will be seen
that such combinations of circumstances will most naturally be found on
islands whose geological history is such that they have had no
connection with adjacent continents, or such a very ancient connection
that they were not then peopled with beasts of prey, while subsequently
their distance from other countries has prevented them from receiving
such population by accident in recent times and has also retarded the
arrival of man.
[11] _The dingo, or native dog, is not forgotten, but, like man, it is a
comparatively recent animal._
[12] _Note that in Tasmania, which is very near Australia, both in space
and in the character of its animals, there are two carnivorous mammals,
the Tasmanian "Wolf" and the Tasmanian Devil, and no flightless birds._
Once established, flightlessness and size play into one another's hands;
the flightless bird has no limit placed on its size[13] while granted a
food supply and immunity from man; the larger the bird the less the
necessity for wings to escape from four-footed foes. So long as the
climate was favorable and man absent, the big, clumsy bird might thrive,
but upon the coming of man, or in the face of any unfavorable change of
climate, he would be at a serious disadvantage and hence whenever either
of these two factors has been brought to bear against them the feathered
giants have vanished.
[13] _While we do not know the limit of size to a flying creature, none
has as yet been found whose wings would spread over twenty feet from tip
to tip, and it is evident that wings larger than this would demand great
strength for their manipulation._
_REFERENCES_
_There is a fine collection of mounted skeletons of various species of
Moas in the Museum of Comparative Zoology at Cambridge, Mass., and
another in the American Museum of Natural History, New York. A few
_other skeletons and numerous bones are to be found in other
institutions, but the author is not aware of any egg being in this
country. Specimens of the AEpyornis are rare in this country, but Mr.
Robert Gilfort, of Orange, N.J., is the possessor of a very fine egg. A
number of eggs have been sold in London, the prices ranging from L200
down to L42, this last being much less than prices paid for eggs of the
great auk. But then, the great auk is somewhat of a fad, and there are
just enough eggs in existence to bring one into the market every little
while. Besides, the number of eggs of the great auk is a fixed quantity,
while no one knows how many more of AEpyornis remain to be discovered in
the swamps of Madagascar. No specimens of the gigantic Patagonian birds
are now in this country, but a fine example of one of the smaller forms,
Pelycornis, including the only breast-bone yet found, is in the Museum
of Princeton University._
_The largest known tibia of a Moa, the longest bird-bone known, is in
the collection of the Canterbury Museum, Christchurch, New Zealand; it
is 3 feet 3 inches long. This, however, is exceptional, the measurements
of the leg-bones of an ordinary Dinornis maximus being as follows:
Femur, 18 inches; tibia, 32 inches; tarsus, 19 inches, a total of 5 feet
9 inches. The egg measures 10-1/2 by 6-1/2 inches._
_There is plenty of literature, and very interesting literature,
about the Moas, but, unfortunately, the best of it is not always
accessible, being contained in the "New Zealand Journal of Science" and
the "Transactions of the New Zealand Institute." The volume of
"Transactions" for 1893, being vol. xxvi., contains a very full list of
articles relating to the Moas, compiled by Mr. A. Hamilton; it will be
found to commence on page 229. There is a good article on Moa in
Newton's "Dictionary of Birds," a book that should be in every library._
[Illustration: Fig. 32.--The Three Giants, Phororhacos, Moa, Ostrich.]
IX
THE ANCESTRY OF THE HORSE
"_Said the little Eohippus
I am going to be a horse
And on my middle finger-nails
To run my earthly course._"
The American whose ancestors came over in the "Mayflower" has a proper
pride in the length of the line of his descent. The Englishman whose
genealogical tree sprang up at the time of William the Conqueror has, in
its eight centuries of growth, still larger occasion for pluming himself
on the antiquity of his family. But the pedigree of even the latter is a
thing of yesterday when compared with that of the horse, whose family
records, according to Professor Osborn, reach backward for something
like 2,000,000 years. And if, as we have been told, "it is a good thing
to have ancestors, but sometimes a little hard on the ancestor," in
this instance at least the founders of the family have every reason to
regard their descendants with undisguised pride. For the horse family
started in life in a small way, and the first of the line, the
Hyracotherium, was "a little animal no bigger than a fox, and on
five[14] toes he scampered over Tertiary rocks," in the age called
Eocene, because it was the morning of life for the great group of
mammals whose culminating point was man. At that time, western North
America was a country of many lakes, for the most part comparatively
shallow, around the reedy margins of which moved a host of animals,
quite unlike those of to-day, and yet foreshadowing them, the
forerunners of the rhinoceros, tapir, and the horse.
[14] _Four, to be exact; but we prefer to sacrifice the foot of the
Hyracothere rather than to take liberties with one of the feet of Mrs.
Stetson's poem._
The early horse--we may call him so by courtesy, although he was then
very far from being a true horse--was an insignificant little creature,
apparently far less likely to succeed in life's race than his bulky
competitors, and yet, by making the most of their opportunities, his
descendants have survived, while most of theirs have dropped by the
wayside; and finally, by the aid of man, the horse has become spread
over the length and breadth of the habitable globe.
[Illustration: Fig. 33.--Skeleton of the Modern Horse and of His Eocene
Ancestor.]
Now right here it may be asked, How do we know that the little
Hyracothere _was_ the progenitor of the horse, and how can it be shown
that there is any bond of kinship between him and, for example, the
great French Percheron? There is only one way in which we can obtain
this knowledge, and but one method by which the relationship can be
shown, and that is by collecting the fossil remains of animals long
extinct and comparing them with the bones of the recent horse, a branch
of science known as Palaeontology. It has taken a very long time to
gather the necessary evidence, and it has taken a vast amount of hard
work in our western Territories, for "the country that is as hot as
Hades, watered by stagnant alkali pools, is almost invariably the
richest in fossils." Likewise it has called for the expenditure of much
time and more patience to put together some of this petrified evidence,
fragmentary in every sense of the word, and get it into such shape that
it could be handled by the anatomist. Still, the work has been done,
and, link by link, the chain has been constructed that unites the horse
of to-day with the horse of very many yesterdays.
The very first links in this chain are the remains of the bronze age
and those found among the ruins of the ancient Swiss lake dwellings; but
earlier still than these are the bones of horses found abundantly in
northern Europe, Asia, and America. The individual bones and teeth of
some of these horses are scarcely distinguishable from those of to-day,
a fact noted in the name, _Equus fraternus_, applied to one species; and
when teeth alone are found, it is at times practically impossible to say
whether they belong to a fossil horse or to a modern animal. But when
enough scattered bones are gathered to make a fairly complete skeleton,
it becomes evident that the fossil horse had a proportionately larger
head and smaller feet than his existing relative, and that he was a
little more like an ass or zebra, for the latter, spite of his gay coat,
is a near relative of the lowly ass. Moreover, primitive man made
sketches of the primitive horse, just as he did of the mammoth, and
these indicate that the horse of those days was something like an
overgrown Shetland pony, low and heavily built, large-headed and
rough-coated. For the old cave-dwellers of Europe were intimately
acquainted with the prehistoric horses, using them for food, as they
did almost every animal that fell beneath their flint arrows and stone
axes. And if one may judge from the abundance of bones, the horses must
have roamed about in bands, just as the horses escaped from civilization
roam, or have roamed, over the pampas of South America and the prairies
of the West.
The horse was just as abundant in North America in Pleistocene time as
in Europe; but there is no evidence to show that it was contemporary
with early man in North America, and, even were this the case, it is
generally believed that long before the discovery of America the horse
had disappeared. And yet, so plentiful and so fresh are his remains, and
so much like those of the mustang, that the late Professor Cope was wont
to say that it almost seemed as if the horse _might_ have lingered in
Texas until the coming of the white man. And Sir William Flower wrote:
"There is a possibility of the animal having still existed, in a wild
state, in some parts of the continent remote from that which was first
visited by the Spaniards, where they were certainly unknown. It has
been suggested that the horses which were found by Cabot in La Plata in
1530 cannot have been introduced."
Still we have not the least little bit of positive proof that such was
the case, and although the site of many an ancient Indian village has
been carefully explored, no bones of the horse have come to light, or if
they have been found, bones of the ox or sheep were also present to tell
that the village was occupied long after the advent of the whites. It is
also a curious fact that within historic times there have been no wild
horses, in the true sense of the word, unless indeed those found on the
steppes north of the Sea of Azof be wild, and this is very doubtful. But
long before the dawn of history the horse was domesticated in Europe,
and Caesar found the Germans, and even the old Britons, using war
chariots drawn by horses--for the first use man seems to have made of
the horse was to aid him in killing off his fellow-man, and not until
comparatively modern times was the animal employed in the peaceful arts
of agriculture. The immediate predecessors of these horses were
considerably smaller, being about the size and build of a pony, but
they were very much like a horse in structure, save that the teeth were
shorter. As they lived during Pliocene times, they have been named
"Pliohippus."
Going back into the past a step farther, though a pretty long step if we
reckon by years, we come upon a number of animals very much like horses,
save for certain cranial peculiarities and the fact that they had three
toes on each foot, while the horse, as every one knows, has but one toe.
Now, if we glance at the skeleton of a horse, we will see on either side
of the canon-bone, in the same situation as the upper part of the little
toes of the Hippotherium, as these three-toed horses are called, a long
slender bone, termed by veterinarians the splint bone; and it requires
no anatomical training to see that the bones in the two animals are the
same. The horse lacks the lower part of his side toes, that is all, just
as man will very probably some day lack the last bones of his little
toe. We find an approach to this condition in some of the Hippotheres
even, known as Protohippus, in which the side toes are quite small,
foreshadowing the time when they shall have disappeared entirely. It may
also be noted here that the splint bones of the horses of the bronze age
are a little longer than those of existing horses, and that they are
never united with the large central toe, while nowadays there is
something of a tendency for the three bones to fuse into one, although
part of this tendency the writer believes to be due to inflammation set
up by the strain of the pulling and hauling the animal is now called
upon to do. Some of these three-toed Hippotheres are not in the direct
line of ancestry of the horse, but are side branches on the family tree,
having become so highly specialized in certain directions that no
further progress horseward was possible.
Backward still, and the bones we find in the Miocene strata of the West,
belonging to those ancestors of the horse to which the name of
Mesohippus has been given because they are midway in time and structure
between the horse of the past and present, tell us that then all horses
were small and that all had three toes on a foot, while the fore feet
bore even the suggestion of a fourth toe. From this to our Eocene
Hyracothere with four toes is only another long-time step. We may go
even beyond this in time and structure, and carry back the line of the
horse to animals which only remotely resembled him and had five good
toes to a foot; but while these contained the possibility of a horse,
they made no show of it.
[Illustration: Fig. 34.--The Development of the Horse.]
Increase in size and decrease in number of the toes were not the only
changes that were required to transform the progeny of the Hyracothere
into a horse. These are the most evident; but the increased complexity
in the structure of the teeth was quite as important. The teeth of
gnawing animals have often been compared to a chisel which is made of a
steel plate with soft iron backing, and the teeth of a horse, or of
other grass-eating animals, are simply an elaboration of this idea. The
hard enamel, which represents the steel, is set in soft dentine, which
represents the iron, and in use the dentine wears away the faster of the
two, so that the enamel stands up in ridges, each tooth becoming, as it
is correctly termed, "a grinder." In a horse the plates of enamel form
curved, complex, irregular patterns; but as we go back in time, the
patterns become less and less elaborate, until in the Hyracothere,
standing at the foot of the family tree, the teeth are very simple in
structure. Moreover, his teeth were of limited growth, while those of
the horse grow for a considerable time, thus compensating for the wear
to which they are subjected.
We have, then, this direct evidence as to the genealogy of the horse,
that between the little Eocene Hyracothere and the modern horse we can
place a series of animals by which we can pass by gradual stages from
one to the other, and that as we come upward there is an increase in
stature, in the complexity of the teeth, and in the size of the brain.
At the same time, the number of toes decreases, which tells that the
animals were developing more and more speed; for it is a rule that the
fewer the toes the faster the animal: the fastest of birds, the ostrich,
has but two toes, and one of these is mostly ornamental; and the fastest
of mammals, the horse, has but one.
All breeders of fancy stock, particularly of pigeons and poultry,
recognize the tendency of animals to revert to the forms whence they
were derived and reproduce some character of a distant ancestor; to
"throw back," as the breeders term it. If now, instead of reproducing a
trait or feature possessed by some ancestor a score, a hundred, or
perhaps a thousand years ago, there should reappear a characteristic of
some ancestor that flourished 100,000 years back, we should have a
seeming abnormality, but really a case of reversion; and the more we
become acquainted with the structure of extinct animals and the
development of those now living, the better able are we to explain these
apparent abnormalities.