Evening star., 1935-11-14

the present. They disappeared, leaving
no descendants. For the most part, they
were tiny creatures, not exceeding the
size Of squirrels.
Apparently they were enjoying
prosperous period when the Crazy Noun
tain formations were laid down. They
are characterized by psychologists as
one Of the greatest Of all mammal or.
ders. They had a continuous history
longer than that of any other race OF
mammals. There distribution was
worldwide.
The multituberculate remains recov-
cred from the Crazy Mountain deposits
belonged, for the most part, Of race
known as ptilodintids. DR.. Simpson finds
at least eight sharply distinct species
among them.
Weird and strange were the carni-
vores. or flesh-eaters. of this ancient
world. DR.. Simpson identifies IA species
of the so-called arctocyonidae, or bear
dogs. This class may have included some
Of the most savage and fearsome crea-
lures the earth has known. One OF
them-a member of the family much
more recent than those whose bones
were found in the Crazy Mountain de-
posits-is described as a doglike creature
about the size of the Kodiak bear, which
is the largest Of all present-day flesh
eaters.
The bear-dogs of the paleocene-it
must be stressed that they were neither
bears nor dogs and were not even re-
motely related to either-were smaller
animals but they may have been no less
ferocious. Like the rest Of the family,
however, they were distinguished by very
large teeth. They probably fed largely
on carrion, crushing the StouteSt bones
with these massive teeth.
Besides the bear-dogs, DR.. Simpson
found bones Of a smaller race Of ancient
fiesh-eating, the miacidae. These, some
psychologists believe, were close to the
ancestral line Of some of the carnivores
of today.
In this collection also are found some
Of the earliest Of the hoofed animals
or creatures approaching the hoofed
mammal type. There are three species
of the amblypoda representing a genus
the best known species Of which was
an animal about the size OF small
sheep and with shorter legs. Unlike
the hoofed creatures Of today they had
no elastic pad on the foot to bear the
weight of the body. There is some
evidence pointing to a relationship with
the primitive f1esh-eaters.
There is no generic relationship be-
tween the amblypoda and any of the
hoofed mammals of today. Some efforts
have been made to associate them with
the elephants but they hardly have
proved convincing. Their evolutionary
progress, however, was somewhat SINH
lar to that Of the elephant line.
Still another order identified by DR..
Simpson in the Crazy Mountain complex
is that Of the condylartha, a group OF
exceedingly primitive ungulates which
seem to serve as bridge between the
hoofed and clawed mammals. That is,
they show the way in which the transi-
ton from claws to hoofs might have
been made. They were not actually re-
lated to any creatures of the present.
The condylartha had five toes, but the
third was enlarged and the first and
fifth shortened, as though preparatory
to their disappearance. The next step
would have been three toes, and then
the transition to the hoof. The ma
jority Of the species found by DR.. Simp-
son belonged to the Phenacodontidae,
creatures ranging in size from the di.
mensions Of fox to those Of small
sheep. They had very small brains.
which may have contributed materially
b thar diasppearanee.