The San Francisco call., 1906-08-26
An interesting Explanation.


The explanation given of this entire
evolution Is most interesting. for 1t
smbodies the chief principles OF all
study of evolutionary science. It = not
only in the alteration OF teeth and toes
that the horse changed during the
thousands of centuries. There is con-
siderable increase in the length OF the
iags, especially OF the lower part. The
surfaces of the joints have changed.
and from being ball and socket joints
playing in all directions they have be-
come grooved like a pulley wheel. per-
hitting freer motion backward and
forward. but little sidewise. making the
joint very strong. The foot Is better
adapted now TO travel over smooth.
regular ground and Is OF little value
for striking and grasping.
The increased length OF lower leg and
foot increases the length o. the stride
without diminishing the quickness. But
the longer lower leg requires addition
al strength. and this is obtained from
the change OF the ball and sockeSjoint
into a pulley joint. Another increase
OF strength was obtained by the horse
by the consolidation OF the two bones
OF the forearm (ulna and radius) and
OF the leg (tibia and fibula) INTO one.
OF course as the horse became taller
the neck had to be heightened for it to
reach the ground in grazing. and the
head too was elongated. The centering
of the step in the middle toe was also
intended to increase the speed over
smooth ground The soft-footed animal
travels well over uneven ground, but at
a loss of speed, because the yielding OF
the foot means loss OF power. A hard
tire on an automobile Is faster than
a pneumatic though rougher riding.
The changes in the character OF the
teeth of the horse were also an accom-
mediation to altered conditions. Re
moved from the forests IL had to live
on the hard dry grass OF the plains and
the teeth changed accordingly.
Geology shows that the earlier types
OF ancestors OF the horse lived IN the
forest. while the later descendants in
habIted the fiat plains. to which they
adapted themselves in the course OF
thousands OF years The increase in
size Is probably due to the survival OF
the fttest. for the larger animals were
better able to defend themselves from
their foes or to fee from them.
The alterations OF climate, changing
the character OF the country. have been
the chief cause OF the evolution OF the
horse. In the early part OF the age OF
mammals the western part OF North
America was at low level. covered BY
heavy forests, and. then the earliest
types OF horse ancestors developed. AS
the forests diminished and plains COW
cred with grass began to appear on
account of the colder. dryer climate the
horse changed his type to conform to
conditions.
With the very complete line OF the
descent OF the horse spread out so that
even the most superficial layman can
understand the various steps of evolu-
tion 1t is seriously to be doubted
whether the discovery Of one or even
OF dozen fossilized gigantic horses
could at stroke alter all these slowly
built up theories OF scientific evolution
lists.
The discovery OF this fossil In Wyo-
ming could hardly be taken seriously
until the experts have examined the
find and decided absolutely that these
are the remains OF horse
1t is more than possible that what
have been found are the remains OF one
of the dinosaurs OF an early period, the
head of which has been mistaken for
that of a horse by some iaexpert ex-
plorer. For instance. the head OF an
Iguanadon to the casual observer might
appear not unlike horses head. This
will probably prove to be the case in
the present instance