Atlanta tri-weekly journal. [volume] (Atlanta, Ga.) 1920-19??, 1922-10-05
1.-THE Mysterious Fate of the Reptiles

Little mysterious rate or the f(epClloS
This great period of Mesozoic life, this sec
ond volume of the book of life, is indeed an
amazing story of reptilian life proliferating
and developing. But the most striking thing
Of all the story remains to be told.
Right up to the latest Mesozoc Rocks we
find all these reptilian orders we have enum-
Grated still flourishing unchallenged. There
is no hint Of an enemy or competitor to them
in the relics we find OF their world. Then the
record is broken We do not know how long
time the break represents; many pages may
be missing here, pages that may represent
some great catacfysmal climatic change When
next we find abundant traces Of the land
plants and the land animals of the earth, this
great multitude of reptile species had gone
For the most part they have left no descen-
dants. They have been wiped OUT
The pterodactyls have gone absolutely, of
the plesiosaurs and ichthyosaurs none is alive;
the mosasaurs have gone; of the lizards a few
remain, the monitors of the Dutch East In
dies are the largest; all the multitude and
diversity Of the dinosaurs have vanished Only
the crocodlleS and the turtles and tortoises
carry on any quantity into Cainozoic times.
The place of all these types in the picture that
the Cainozoic fossils presently unfold to us
taken by other animals not closely related to
the Mesozoic reptiles and certainly not de-
scended from any of their ruling types. A new
kind of life is in possession of the world.
Were They Frozen Out?
This apparently abrupt ending up of the
reptiles is, beyond all question, the most
striking revolution in the whole history of the
earth before the coming of mankind. 1t is
probably connected with the close of a vast
period OF equable warm conditions and the
onset of new austc .er age, in which the win
ters were bitterer and the summers brief but
hot. The Mesozoic life, animal and vegetable
alike, was adapted to warm conditions and ca
pable of little resistance to cold. The new
life, on the other hand, was before all things
capable of resisting great changes Of tempera-
ture.
Whatever it was that led to the extinction
of the Mesozoic reptiles, it was probably some
very far-reaching change indeed, for the life
of the seas did at the same time undergo a
similar catastrophe alteration. The crescen-
do and ending Of the reptiles on land was par
alleled by the crescendo and ending of the
Ammonities, a division of creatures like
squids with coiIed shells which sWarmed in
these ancient seas.
All through the rocky record of this Meso-
zoic period there is a vast multitude and va
riety of these coiled shells; there are hundreds
Of species, and toward the end of the Meso-
zoic period they increased in diversity and
produced exaggerated types. When the record
resumes these, too, have gone. So far as the
reptiles are concerned people may perhaps be
inclined to argue that they were exterminated
because the mammals that replaced them
competed with them and were more fitted to
survive; DuL uOtulHS u Cn0 SOrC can De True
of the Ammonites, because to this day their
place has not been taken. Simply they have
gone. Unknown conditions made it possible
for the14- to live in the Mesozoic seas, and then
some unknown change made life impossible
for them.
No genus of Ammonite survives today of
all that vast variety, but there still exists one
isolated genus very closely related to the AM
monites the Pearly Nautilus. 1t is found, it
is to be noted, in the warm waters of the In
dian and Pacific oceans.
And as for the mammals competing with
and ousting the less fit reptiles, a struggle
of which people talk at times, there is not a
scrap Of evidence of any such direct compe-
tition. To judge by the Record of the Rocks
as we know it today, there is much more rea-
son for believing that first the reptiles in
some inexplicable way persisted, and then that
later on, after very hard time for all life
upon the earth, the mammals, as conditions
became more genial again, developed and
spread to fill the vacant world.
Were there mammals in the Mesozoic pc
Rod?
This is a question not yet to be answered
precisely. Patiently and steadily the geolo-
gists gather fresh evidence and reason out