The Tucumcari news. [volume] (Tucumcari, N.M.) 1905-1907, 1906-04-14
III ~
The Horses Dental Battery.

- 10 lhleIeSlluS 10 STUDY eVOlultOn
relating to the m~asticating apparatus
OF the horse, which someone has aptly
termed his dental battery" Vhe
prehistoric or dawn" horse was a
Ilttle, fawn-colored, spotted aninal
NOT over eleven inches higt and With
such short-crowned teeth that they
wore out in eight or ten years, so
mat he succumbed from inability to
chew food. This little horse had i've
toes and was little like our modern
representative Of the equine race, but
gradually. through a few millions of
years. 1t is supposed, changed in type.
Trace has been found of him grown
10 fourteen inches in height, thon
eighteen inches, or about as big as g
sheep and later to forty inches, or
the average height of a Shetland pony
there are several different types.
zoe, and the teeth in each were gradu-
any increasing in length and size =
crown and reducing in number, for the
prehistoric horse had sever molars on
each side above and below while the
modern horse has but six, in each jaw.
AS the four superfluous toes became
eNtlnct. so to speak, the middle toe
OF digit enlarged and strengthened,
ana was fitted with a foot, making it
the most perfect standing, walking
and running weight-carrier extant. All
the while, too, the mouth was length.
ening and the molar teeth increasing
Ia width n length, so that in the
modern horse at least we find a set
OF moiars so strong and long that they
can well withstand twenty-five to
thirty years Of masticating.
n composition of these molar
teeth is ~marvelously perfect for the
purposes which they fulfill. They are
made of three materials of different
densities, and as the wear of each Is
necessarily different the bearing sur.
race OF each tooth is consequently
Kept rough, so that it may grind we'll,
as Toes the burr stone of a grist mill.
Ihe threo constituent substances of q
tooth are Dentine, which is composed
or 10 pei cent earthly material and "a
per cent animal matter; Enamel, 50
per cent earthly matter and 5 per cent
animal matter; Cement, CT per cent
eartfy matter and 33 per cen animal
matter. The enamel is present in
irregular curves and cylinders and col.
uinns from one end of the tooth to the
other and between these layers Is the
dcntine and the cement.
The enamel at all times proiects
above the other substances of the
tooth and gives the necessary rough.
ness for food grinding. In the young
colt the molar teeth (%permanent) are
SO long that their roots are close I'D
to the eye In the skull, but as the
animal ages the crowns gradually
wear dow and the necessary surface
for mastication is supplied by gradual
descent or the molar. The tooth does
not grow, as some enormously think,
but II m down in its socket so
that the root Is constantly becoming
nearer and nearer to the gums, and is
quite short by the time the horse is
thirty years old.
The milk teeth are small, white an
smooth. The permanent teeth (ncis
ors or %nippers) are large, broad. vel
io"lsh IN corof N nave deep, brown.
ish yellow marks down their front sur.
faces. On the grinding surface of the
upper and lower incisors tnere arc
cups surrounded by black.colored rims.
These are the marks" by which ono
can closely approximate the horses
age. When the full complement OF
milk teeth Is present the first change
Is the substitution of two permanent
incisors above and below in the cen.
ter. This happens at from two years
aud nine months to three years; at
three and a half to four years the
lateral or second pair of incisors come
In, and n four and a half to five years
the corner or third pair Of i~nclsors
appear and along with them Gin
malcs) the tushes or bride teeth.