Evening star., 1937-07-17

FOSSILS Ol NOME OI LnS eaTLn = earliest
mammals, remote ancestors Of the pres
ent mammalian fauna of the earth, in
cluding man. have been added to the
collections OF the Smithsonian Institu-
ton.
Last Summer specimens represent
alive OF more than 50 species were OBJ
tained from the so-called Puerco and
Torrejon areas in New Mexico by DR..
C. Lewis Gain. Smithsonian paleontol-
ogist. Respectively, these formations
date back approximately 60 900 900 and
$4,000 900 years. They represent the
period when mammals first appear as
the dominant creatures ON earth.
These were not the first mammals.
There were mammals and mammal-like
forms during the preceding Mesozoc
period, when the great dinosaurs were
becoming extinct. But these earlier
warm -blooded creatures we're of little
importance in the mesozoic life pattern.
At the beginning Of the Paleocene period
the race came into its rich inheritance
from the great reptiles OF mastery over
the planet, which 1t has held ever since.
When they appeared the dinosaurs were
gone. About the only formidable rem
nants of the old line were crocodtielike
saurians, specifically hardly distin-
guishable from crocodiles of today.
These paleocene mammals were. an
awkward. stupid lot, but they had ca
pacities for development and adjustment
which their predecessors apparently
lacked. Somewhere among them, al
though direct lines cannot be traced.
we're probably the ancestral strains Of
all the mammal types known today.
These mammals were already differ
entiated into two broad groups-the
herbivores and the carnivores. The
terror Of these ancient millenniums was
probably the uiisodon, 4 flesh eating
creature about the size Of 4 collie dog
which presumably preyed upon the
weaker herbage -eating animals. 1t
might be compared TO 4 very clumsy
bear in general appearance and would
cut q sorry figure in the world of today.
Among the commonest creatures was
the ectoconus, somewhat smaller than
the triisodon and a herbage eater An
other was the psittacotherium. the size
of 4 small pig with an enormous piglike
head, which some believe to have been
in the ancestral line Of the ground
sloths, which became extinct in North
America only with the end of the ice age.
All this fauna disappeared millions
of years ago, and there Is nothing alive
today which even looks like them, ex-
cept in q very general way. They would
bear about the same resemblance to the
mammals of today rs the crude, fan
tastic automobiles of the nineties to the
latest streamlined models. All their
structures were very generalized. They
had not developed the anatomical spe-
Civilizations, such as hoofs for swift run
ming, by which various extant mammal
families have adapted themselves to
meet competition.
The majority OF these creatures, ac-
cording to recent monograph on the
beginnings of the age Of mammals by
George Gaylord Simpson of the Amer
tcan Museum Of Natural History, repre-
sent an invasion Of North America from
some unknown evolutionary center. 1t
ia no longer, he holds, tenable to assume
that they were the descendants Of the
very primitive mammals which were con-
temporaries Of the great reptiles in the
upper Cretaceous.
Somewhere on earth, he says. must be
assumed . great land mass separated for
millions of years from North America
probably by an unpassable ocean. Then
this land mass became joined with North
America and the animals could pass
freely from enc to the other. This un-
known land mass, Of continental pro-
portions. was the cradle Of the mallalian
races Of today. Conditions must have
been extremely favorable for their de-
velopment. While the old North Amer
iosn forms. eompstsng h the rep&aEes
tor existence and peoloaka faring poorly,