More Science from an Easy ChairLankester, E. Ray (Edwin Ray), Sir
History
More Science from an Easy Chair
Lankester, E. Ray (Edwin Ray), Sir
Natural history; Science
In the higher races of men the jaws are shorter than in the
lower races, and project but very little beyond the vertical plane of
the eyes, whilst the nose projects beyond the lips. Another exception
is the elephant. This is most obvious when the prepared bony skull and
lower jaw are examined, but can be sufficiently clearly seen in the
living animal. The lower jaw and the part of the upper jaw against
which it and its grinders play is extraordinarily short and small. The
elephant has, in fact, no projecting bony jaw at all, no bony snout,
its chin does not project more than that of an old man, and even the
part of the upper jaw into which its great tusks are set does not bend
forward far from the perpendicular (Fig. 9).
[Illustration: Fig. 11.--A reconstruction of the extinct American
mastodon (_Mastodon ohioticus_) from a drawing by Prof. Osborne. Other
extinct species of mastodon are found in Europe.]
[Illustration: Fig. 12.--A. Skull, and B. restored outline of the head
of the long-jawed extinct elephant called Tetrabelodon--the name
referring to its four large tusks--two above and two below.]
The elephant (see Fig. 9) has no sign of the six little front teeth
(incisors) above and below which we find in the typical dentition and
in many living mammals, nor of the corner teeth (dog-teeth, or
canines). In the upper jaw in front there is the one huge tusk on
each side, and in the lower jaw no front teeth at all! Then as to the
grinders. In the elephant these are enormous, with many transverse
ridges on the elongated crown, and so big that there is only room for
one at a time in each half of upper and lower jaw. Six of these
succeed one another in each half of each jaw, and correspond (though
greatly altered) to six of the seven grinders of the typical
dentition. Are there amongst older fossil elephants and animals like
elephants any which have an intermediate condition of the teeth,
connecting the extremely peculiar teeth of the modern elephants with
the typical dentition such as is approached by the pig, the dog, the
tapir, and the hedgehog? There are such links. We know a great many
elephants from Pleistocene and Pliocene strata--some from European
localities, more from India, and some from America. A little elephant
not more than 3 feet high when adult is found fossil in the island of
Malta; other species were a little larger than the living African
elephant. Whilst the Indian elephant has as many as twenty-four
cross-ridges on its biggest grinding tooth (Fig. 8) there is a fossil
kind which has only six such ridges. But besides true elephants we
know from the Pliocene, Miocene, and Upper Eocene of the old world,
the remains of elephant-like creatures (some as big as true
elephants), which are distinguished by the name "Mastodon" (Fig. 11).
And, in fact, we are conducted through a series of changes of form by
ancient elephant-like creatures which are of older and older date as
we pass along the series, and are known as (1) Mastodon, (2)
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