Evening star., 1937-01-16
STARS, MEN AND ATOMS
Notebook of Science Progress in Field,
Laboratory and Study.
THOMAS HENRY

A notable link in the equine family
tree-connecting the earliest true horses
with their North American ancestors
who lived just before the last ice ages
has been reconstructed by c. Lewis
Gain. Smithsonian Institution paleon-
tOlogist.
Of l30 animals, together with q great
deal Of other skeletal material, obtained
by four Smithsonian expeditions to the
Snake River basin near Hagerman,
Idaho. 1t was probably the most ex-
tensive collection ever made Of the bones
OF n long extinct animal.
The creature Is known scientifically as
Plesippus shoshoniensis. Geological eVi-
dence indicates that 1t lived, probably in
enormous numbers, during the late Plio-
Gene period Of the geologiSts. This was
more than 10000 years ago and just pre-
ceded the spread southwark OF the
great ice sheets which made q large part
Of the continent u refrigerator for sew
eral millenniums. During intervals be-
tween the elaCiationS. fossil remains
show, there roamed over the Great
Plains herds OF hoofed creatures hardly
different from the horses of today and
representing only different species Of the
horse family. They survived. Mr.. Gain
believes, almost into historic times. They
were extinct before the coming Of the
Spsniards, but few may have fingered
OH almost up 10 that time.
This animal, however WAS not actually
a horse, but represented distinct genus
OF the equine family no member of which
still is extant. Superficially, Mr.. Gain
points out, its bones are almost indistin-
guiShable from those of the large African
zebra OF the present day-a near rela-
tive OF the horses. Probably a herd Of
these "plesippi' would have looked very
much like q herd Of zebra so far as
body form Is concerned. They may, or
may not, have had the zebras stripes.
Mr. Gain does not believe that these
creatures were actual ancestors Of pres
ent-day horses, but that both were de-
rived from q common ancestor Of the
early PliOcene period.
The reconstruction adds another link
to what Is already one Of the best known
and most complete fossil records fur
nished by any group OF mammals, Mr..
Gain says. The development of the
horse throughout the Tertiary time pre-
ceding the ice ages was nearly con-
tinuous on the North American conti-
nent, with only occasional hiatuses in
the sequence.
The great bulk Of the materials OBJ
tanned by the Smithsonian expeditions
came from q lens of reddish, bog g-iron
stained sand near Hagerman. This sug-
gests bOggy conditions during the accu-
mutation of the bones. The creatures
may have come to their ends near q water
hole. or may have become trapped in
= bog or In quicksand. There is every
reason to believe, Mr. Gazin says, that
they died near where the fossil bones
were found, since there is no evidence
that they were transported for any dis
tance.
Further evidence of the swamp condi-
tionS Of the country in late Pliocene
time is afforded by the other animals
represented by the fossils collected there.
They are mostly Of creatures having an
aquatic habit. Fish and frog remains
are of common occurrence. The bird
bones, though rare. are all Of creatures
which would be expected to frequent