Full text of "Fossils What They Tell Us Of Plants And Animals Of The Past"

See other formats

S< OU_1 62960 >m

OUP 552 7-7-6610,000

OSMANIA UNIVERSITY LIBRARY

Accession No. 3 3

This book should be returned on or before the date
last rnarked below.

The UNIVERSITY SERIES

Highlights of Modern Knowledge

Titles Now Available

STARS AND PLANETS DONALD H. MENZEL, PH.D.

Associate Professor of Astronomy, Harvard University

THE EARTH CHESTER A. REEDS, PH.D.

Curator of Geology, American Museum of Natural History

THE PLANT WORLD C. STUART GAGER, PH.D., Sc.D.

Director of Brooklyn Botanic Garden

THE ANIMAL WORLD

JAMES GEORGE NEEDHAM, Pn.D., Lrrr.D.
Professor of Entomology and Limnology, Cornell University

FOSSILS RICHARD SWANN LULL, PH.D., ScD.

Director of Peabody Museunij Yale University

COMING AND EVOLUTION OF LIFE

HENRY E. CRAMPTON, PH.D., Sc.D.
Professor of Zoology, Barnard College, Columbia University

HEREDITY AND VARIATION L. C. DUNN, D.Sc.

Professor of Zoology, Colu77ibia University

THE COMING OF MAN

GEORGE GRANT MACCURDY, PH.D.
Yale Univ., Director, American School of Prehistoric Research

THE RACES OF MAN ROBERT BENNETT BEAN, M.D.

Professor of Anatomy, University of Virginia

THE SMALLEST LIVING THINGS

GARY N. CALKINS, PH.D., Sc,D.
Professor of Protozoology, Colu??ibia University

ENERGY AND MATTER. . . .CHARLES B. BAZZONI, PH.D.

Professor of Experimental Physics, University of Pennsylvania

SPACE, TIME AND RELATIVITY

H. HORTON SHELDON, PH.D.
Professor of Physics, New York University

THE DRAMA OF CHEMISTRY. SIDNEY J. FRENCH, PH.D.
Assistant Professor of Chemistry, Colgate University

FOSSILS

What They Tell Us of Plants and Animals of the Past

By RICHARD SWANN LULL, PH.D., Sc.D.

STERLING PROFESSOR OF PALEONTOLOGY AND DIRECTOR OP
PEABODY MUSEUM. YALE UNIVERSITY

Highlights of Modern Knowledge

PALEONTOLOGY

THE UNIVERSITY SOCIETY

INCORPORATED

NEW YORK

INCORPORATED

Manufactured in the U. S. A.

CONTENTS

CHAPTER PAGE

I ,THE SIGNIFICANCE OF FOSSILS 1

Ancient Interpretations of Fossils Fossils Visualize the
Geologic Past Fossils Prove Evolution

II THE NATURE AND ANTIQUITY OF FOSSILS 4

Definition of a Fossil Classification of Fossils Fossils
Actually Preserved in Ice or Frozen Soil, in Oil, or in
Amber Petrification Natural Molds or Casts Fossil
Footprints and Trails Coprolites Artificial Structures

III THE NUMBER AND AGE OF FOSSILS 17

A Census of Fossils How the Age of Fossils is Deter-
mined Stratigraphical Geology

IV THE LOCATIONS OF FOSSILS 21

Marine Fossils The Continental Shelf Deep-Sea Fos-
sils Estuarine Deposits River Bars and Deltas Old
Inland Sea Bottoms Terrestrial Fossils Flood-plain
Deposits Peat Swamps and Quicksands Coal Swamps
Asphalt Beds Some Famous Localities of Fossils Soln-
hofen, Bavaria Agate Spring Quarry, Nebraska Mount
St. Stephen Region, British Columbia Bone Cabin
Quarry, Wyoming South Joggins, Nova Scotia Are
Fossil Remains Still Being Discovered?

V FOSSILS AND THE THEORY OF EVOLUTION 41

VI PLANTS AND ANIMALS OF THE PAST 45

The Paleozoic Era The Cambrian Period The Ordo-
vician Period The Silurian Period The Devonian Pe-
riod The Carboniferous Period The Permian Period
The Mesozoic Era The Triassic Period The Jurassic
Period The Cretaceous Period Other Great Reptiles
Mesozoic Birds The Warm-blooded Mammals Extinc-
tion of the Great Reptiles The Cenozoic Era The
Archaic Mammals The Modernized Mammals

VII FOSSIL HORSES* , 79

The Differences Between the Horse and His Unknown
Ancestor The Ten Stages in the Evolution of the Horse
iii

iv CONTENTS

CHAPTER PAGE

VIII FOSSIL ELEPHANTS AND MASTODONS 85

Adaptations of Skulls and Noses Peculiar Dental Fea-
tures From Moeritherium to Mastodon and Elephant
Paleomastodon The Four-tuskers The American Mas-
todon Adaptations Among Elephants Elephants in
North America The Woolly Mammoth The Tallest
Elephant Summary

IX FOSSIL MEN 93

The Ape-Man of Java The Heidelberg Man The
Piltdown Man The Peking Man The Neanderthal
Man The Rhodesian Man Modern Man Whence
Came the Fossil Men of Europe?

X EXTINCTIONS AND THEIR CAUSES 99

Two Forms of P^xtinction Changes in Physical Environ-
ment Changes in Biotic Environment Internal Causes

XI THE UTILITARIAN VALUE OF FOSSIL REMAINS 103

Fossils an Index to Oil and Coal A Legal Illustration
of Fossil Importance Fossils a Source of Petroleum

SUGGESTIONS FOR FURTHER READING 106

GLOSSARY 107

INDEX 109

FOSSILS

MThat They Tell Us of Plants and
Animals of the Past

BY RICHARD SWANN LULL, PH.D., Sc.D.

STERLING PROFESSOR OF PALEONTOLOGY
AND

DIRECTOR OF PEABODY MUSEUM
YALE UNIVERSITY

Dedicated
To the Memory of

OTHNIEL CHARLES MARSH
Pioneer Paleontologist

Who assembled and presented
the great collections at Yale

PREFACE

TO WRITE a book on Fossils that would appeal to the average
person by reason of its satisfying interest as well as by its
instructive qualities was a somewhat serious undertaking, but
the endeavor has proved an intriguing task.

The story of Fossils what they are and what they teach
is a thoroughly fascinating one, and involves a great deal more
of real interest to every one of us than is generally realized.
When we consider that Fossils constitute all of our documentary
evidence concerning the character and evolution of the plants,
animals, and men of prehistory we see how very necessary is
this study to any correct knowledge and understanding of life,
past and present.

I am greatly indebted to my publishers for their sympathetic
appreciation of the task they have assigned me, but especially
to my colleague, Professor Carl O. Dunbar, who has read and
criticized the work, as well as to my research assistant, Miss
Nelda E. Wright, who has prepared the manuscript for the
press and aided materiallv in preparing the illustrations.

Yale University
November, 1931.

W -52

r 1 ^ 1

> I 2!

u *

Sli

CHAPTER I

THE SIGNIFICANCE OF FOSSILS

IN THE ancient city of Verona there is a most admirably pre-
served Roman amphitheater, which was begun during the
reign of the emperor Diocletian,* and which after falling into
partial ruin was restored in the sixteenth century by Leonardo
da Vinci. Most of us look upon the latter as an inspired painter
and sculptor, and his Last Supper, painted on the walls of the
chapel at the convent church of Santa Maria delle Grazie in
Milan, is still one of the loveliest things ever created by the
hand of man. But Leonardo da Vinci was also noted both as
an architect and as an engineer; he dug canals in northern Italy,
and thus was familiar not only with the rocks of that region,
but with their contents as well. It is said that occasionally the
workmen called his attention to the shells and other comparable
objects found in these rocks and brought them to him, asking
what manner of things they were, and that he was among the
first to recognize their true identity as relics of bygone animals.
Here and there, embedded in the stones which formed the
benches of the amphitheater, huge coiled ammonite shells!
may still be seen, possibly some of the very specimens which
the inspired eyes of Leonardo saw for the first time in their true
significance.

ANCIENT INTERPRETATIONS OF FOSSILS

The ancients had very different ideas concerning these ob-
jects, and some of them bear recounting for their historic in-
terest. Fossils were thought to be failures of a creative force
within the earth, or caused by a u stone-making force, " or a
"formative quality/' and so on; they were looked upon as
mere mineral forms which by chance resembled shells or bones;

* Diocletian was emperor of Rome, 284-313 A.D.
t See Figure 9 in "The Earth" in this Scries.

2 FOSSILS

they were explained by such scholastic phrases as u fatty matter
set into fermentation by heat/' or of a u lapidific juice," or of a
"seminal air/' or of a "tumultuous movement of terrestrial ex-
halations" none of which was really explanatory after all.

To call them "sports of nature," particularly if these
"sports" indicated some inscrutable purpose of the Almighty,
answered the question fairly well, especially as the word "in-
scrutable" dismissed them at once from further investigation
by a pious mind.

Even when the shells were recognized as such, they were
thought to have been left as relics of some bygone flood, for the
ideas of vast antiquity and extinction had not yet dawned in the
minds of men. An interesting specimen came to light at Oen-
ingen, Baden, and was thought by its discoverer to represent a
human victim of the flood. It was described as "Homo diluvii
testis," and the following admonitory verse goes with it:

Oh sad remains of bone,
Frame of poor man of sin,
Soften the hearts and minds
Of sinful recent kin.

Huge elephantine bones were hung up in the churches and
other public places for the edification of the faithful, as they
were supposed to be relics of the giants mentioned in the Bible.
From them Henrion drew up tables showing the dimensions of
our antedeluvian forebears. In these Adam was recorded as
123 feet, 9 inches, and Eve as 118 feet, 9 inches, and 9 lines,
tall !

Others saw in the fossils the work of the devil, either to
mar the Creator's handiwork, or to tempt the unwary away from
the straight and narrow path of revealed religion, or, although
in the minds of some twentieth century people this might prove
beneficial to humanity as a whole, to confuse scientists I

As a matter of fact, Leonardo was absolutely right, and
although occasionally clay concretions and other purely mineral
phenomena do look surprisingly like objects of organic origin,
the genuine fossil can have no other than Leonardo's interpre-
tation. Although some of them have certainly given rise to
dispute among scientific men, this is due not at all to their actual
character, for not only are they of immense interest and help

THE SIGNIFICANCE OF FOSSILS 3

in deciphering the history of the globe, but their evidence, when
correctly interpreted, is absolutely unassailable.

FOSSILS VISUALIZE THE GEOLOGIC PAST

Fossils serve as the only means whereby we are able to
visualize the past, for they are indicative of climates and of
limitations of land and sea and give us 'all the discernible facts
which we possess concerning plants, animals, and men, in the
millions of years of geologic time. As such their story is not
only an authentic but a deeply interesting one, and from no other
source may this history be told.

Many have tried to discount fossil evidence, either through
ignorance, prejudice, or because of the apparent difficulty of
reconciling it with their religious beliefs. The same has been
true of other great scientific generalizations as well, and men
have suffered ostracism and mental and physical torment in the
upholding and vindication of what has been accepted ultimately
as the truth. I refer to the great controversial^ questions of
medieval time, such as the form of the universe and the sphericity
and movement of the earth in its orbit. That the truth of these
great questions was later established without violence to religious
faith shows that the facts taught by the fossil evidence will also
come eventually into full acceptance.

FOSSILS PROVE EVOLUTION

The science of fossils Stands as the final court of appeal
when the doctrine of evolution is brought to the bar, for not
only does it present an immense array of facts, not one of which
is out of harmony with the evolutionary idea, but there is no
other hypothesis ever conceived by man which can truly account
for them. The only questions which can arise are those of
interpretation, or of adequate restoration of missing parts, or
of relationships of the organisms to one another, because these
are often questions of opinion only; of the finally established
facts which the fossils proclaim, we are as certain as we are of
anything in this world.

CHAPTER II

THE NATURE AND ANTIQUITY OF

DEFINITION OF A FOSSIL t

THE word fossil is derived from the Latin fossilis, which in
turn comes from fodere, meaning to dig up, antl in older
usage implied anything which was dug out of the earth, whether
mineral, rock, or organic in origin. Later the term was re-
stricted to include the organic only and not the minerals or
rocks.

The first prerequisite for fossilization is natural burial, and,
as Huxley once said, the remains of a sheep buried under the silt
of a recent flood would come, strictly speaking, under this head.
Usually, however, antiquity is implied, and by geologists the
term is confined to the remains of animals and plants which lived
before the dawn of the Recent era.* The necessity for burial
is obvious, for exposed remains of animals and plants usually
decay. They must, therefore, be hermetically sealed, and, while
they may remain either wet or dry, alternation between these
two conditions tends to hasten oxidation and hence destruction
not only of the soft parts but also of the hard parts. Usually
those animals which have hard parts, such as limy shells and
bones, are more readily preserved, but in certain rare circum-
stances the most delicate and fragile things, such as the remains
of jellyfish, may leave a record almost as durable as time itself.

CLASSIFICATION OF FOSSILS

Fossils are grouped under several convenient heads accord-
ing to the manner of their preservation. It must be realized,
however, that as the chances for such preservation are rare
indeed today, so they must have been in bygone days. Thus
the existing fossils must represent an extremely small fraction
of the organisms which actually lived in the geologic past.

* See chart of "Geologic Chronology," pages 46-47.

THE NATURE AND ANTIQUITY OF FOSSILS 5

Furthermore, those which have been discovered and collected
represent again but a small percentage of those which yet lie
buried in the earth's strata, or of those which did exist for a
time only to be destroyed by the various natural agencies which
are continuously fretting the surface of our globe. The several
sorts into which fossils as such are conveniently divided are as
follows :

( 1 ) Fossils Actually Preserved in Ice or Frozen Soil, in Oil,

or in Amber

The first of these include certain arctic animals, especially
the hairy mammoth (Elephas primigenius) , and the woolly
rhinoceros (Rhinoceros tichorhinus) occasionally found within
the confines of the arctic circle, in the Siberian tundras, and also,
to some extent, in Alaska.

These are animals which succumbed during the period of
glacial cold and, once frozen, have never subsequently thawed.
Siberian mammoths occasionally come to light, such as the
famous one discovered in the Lena delta in 1799, collected seven
years later, and transferred to the St. Petersburg (now Lenin-
grad) Museum where the mounted skeleton, with portions of

Fig. ! THE BERESOVKA MAMMOTH FOUND FROZEN IN SIBERIA

Not only were the skeleton and hide intact, except for part of the exposed trunk, but
also the flesh and the internal organs

6 FOSSILS

the hide adhering, may still be seen. Another mammoth was
discovered at Beresovka, Siberia, which lies some 800 miles west
of Bering Strait and 60 miles within the arctic circle (Fig. 1).
In this instance the animal was practically intact when discovered,
except that the exposed trunk had been partially devoured by
wolves. The natives hold such discoveries in superstitious awe
and will have nothing to do with them; they will not even report
a find to those who might recover the specimen. In this instance,
however, an expedition from the St. Petersburg Museum arrived
in time to secure the animal before it was too late. Not only
were the skeleton and hide, except for the mutilated trunk, in-
tact, but also much of the hair, together with the soft parts,
flesh, and internal organs. In the chest there was a mass of
clotted blood, and between the clenched teeth lay the last morsel
of food, showing how quickly death had overtaken the victim.
He had evidently slipped backward into a crevasse and made
violent efforts to escape, as the clotted blood from a ruptured
blood vessel and a broken hip and a broken forearm testify.
One authority, Tolmachoff,* records no fewer than thirty-nine
localities in northern Siberia where frozen carcasses were found
between the years 1692 and 1923. In addition to these, thou-
sands of tusks have been secured, of which a certain percent
was good marketable ivory. In fact, most of the Chinese ivory
carvings are from this source.

The woolly rhinoceros is rarer, and no museum possesses a
complete skeleton, though several skulls with adhering skin have
been found.

The Alaskan ice cliffs have yielded mammoth remains with
hide, muscles, and the fat somewhat altered into a material
known as-adipoccre but thus far no complete carcasses.

Oil-saturated soils have proved another, though rarer, means
of preserval. In 1907 the carcass of an extinct rhinoceros was
discovered in the oil and wax region near Bohorodcrany, eastern
Galicia, Poland. Here the nasal horn, a foreleg, and much of
the skin were found some six feet below the surface. There is
also published the previous finding of a nearly complete mam-
moth in the same locality.

* Prof. I. V. TolmachofT (1872- ), Carnegie Museum, Pittsburgh, in Trans-
actions of the American Philosophical Society (N. S.) XXIII, 1929.

THE NATURE AND ANTIQUITY OF FOSSILS 7

Specimens of ground sloths (Nothrotherium) have been
found in southwestern United States, especially at Gypsum Cave
in New Mexico. At Aden Crater, also in New Mexico, a mar-
velously preserved specimen was discovered in an old volcanic
vent 100 feet underground, buried in bat guano which had been
accumulating for centuries. This skeleton, held in articulation

Fig. 2 THE GROUND SLOTH^NOTHROTHERWM

Found at Aden Crater, New Mexico, in 1928. The skeleton is held in articulation by
its tendons and sinews. It also retains the claws and portions of the hide and hair

(After Lull)

by its tendons and sinews, with the claws and portions of hide
and hair still attached, is now in the Museum of Yale Univer-
sity (Fig. 2). Doubtless in these instances the extremely dry
atmosphere desiccated the animal before extensive decay set in,
the guano being merely contributory to the preservation.

In all of these cases where the original animal material is
preserved, the creatures are of relatively recent age, geologically
speaking, amounting to some thousands of years perhaps, but
that is all. At any rate, the animals are all extinct and of a
Pleistocene* character if not actually Pleistocene in time.

Yet another method of preserval is in amber, the fossil gum

* See chart of "Geologic Chronology," pages 46-47.

8 FOSSILS

or resin which exuded from the trunk and limbs of pine trees,
especially Picea succinifera, which lived in Europe during
Oligocene* time. When first secreted, this resin was sufficiently
Courtesy of Dr. Cari Dunbar s ft to entrap and engulf such

fragile forms as insects and
spiders. Later, the more vola-
tile portions of the gum having
evaporated, it hardened into am-
ber without doing the slightest
damage to the contained crea-
IN A tures, which are preserved with

on, , , A , . .. body, wings, and even the most

The amber is the hardened gum which J & '

exuded ^^^"^^"n P delicate hairs entire. The am-

ber itself may also be consid-

ered a fossil, and hence both the medium and the preserved
object come under the same general heading.

Most of our knowledge of fossil ants is derived from
amber-preserved specimens (Fig. 3); of insects in general and
spiders about two thousand species are known from this source,
as well as over a hundred species of plants. The Baltic amber
is found about Konigsberg and along the coast of Samland,
Germany. The action of the sea washes away the sediments
and leaves the amber pebbles exposed on the beach. They have
been a valuable commercial product for many years.

(2) Petrification

The term petrification (i.e., turning to stone) is so often
used by the uninformed as though Tt were synonymous with fos-
silization that it is well to make the matter clear. A petrifica-
tion is a fossil. On the other hand, there are many fossils
which are in no sense petrified hence the terms are not co-
extensive. Petrification applies to those fossils in which the
animaljTiattejMS partly or wholly replaced Ky some mineralizing
substance, such as iron oxide, pyrites^ sulphur, malachite, mag-
AesiteV carbon, or jjjhca. At first a bone or shell, for instance,
loses its animal matter, leaving behind the calcium phosphate
mineral matter only. Then infiltrating water, carrying the

* See chart of "Geologic Chronology," pages 46-47.

THE NATURE AND ANTIQUITY OF FOSSILS 9

Fig. 4 A CYCAD TRUNK (Cycadeoideo
colossalis)

From the Cycad National Monument, near
Edgemont, South Dakota. Some of these pet-
rified stems reach a weight of 800 pounds

petrifying agent in solution,
gradually invades the object, fill-
ing the spaces which the animal
matter formerly occupied, and
the specimen gains noticeably in
weight, although the original ma-
terial is still there and its struc-
ture, even in minute detail, is
unimpaired. The greater part
of fossil bones of Cenozoic*
mammals, if not all of them, are
in this state. Even the bones
of dinosaurs of the Mesozoic,*
whose age is measured in tens of
millions of years, have still
enough of their original phos-
phates left to form food for
plants, whose roots sometimes penetrate and aid in disinte-
grating the bone. Later the specimen may be entirely replaced,
and one gets what is known as a pseudomorph, which preserves
the general form of the original object but not its minute
structure. (See Figure 26, on page 48.)

Another phase of petrifi-
cation is histometabasi^t or
molecular replacement. In this
process, as the original material
disappears, it is replaced mole-
cule for molecule by the petrify-
ing agent, so that not only is the
external form preserved but the
minute or histologic structure as
well. Obviously this replace-
ment must precede any decay,
otherwise the detailed structure
Fig. 5 SECTION o* A russiL wjAu would be lost. Hence its rarity

'Showing the detailed structure of a young ^n^ilc c

undeveloped frond ln animals as

* See chart of "Geologic Chronology," pages 46-47.

t From two Greek words, histon, meaning tissue, and metabasis, meaning
exchange.

10 FOSSILS

plants, because the rate of disintegration of the former is so
much more rapid.

The fossil cycads, allied to the existing sago palms, which
are found in such perfection in Mesozoic* rocks, are remarkable
instances of histometabasis, for not only will a thin section of
the trunk exhibit wonderful details of structure beneath the
microscope, but by sectioning the developing buds, the long van-
ished foliage, as well as the flowers, may be reconstructed with
scientific precision. t (See Figures 4 and 5.)

Although the term histometabasis is usually applied to plant
tissues, some remarkable instances of comparable preservation
of animal remains have also come to light. Thus, from the
shales of Devonian age found near Cleveland, Ohio, the Ameri-
can zoologist, Bashford Dean (1867-1928), demonstrated not
only the flesh but even the kidneys of fossil sharks of the genus
Cladoselache. He illustrated the miscroscopic structure of
Cladoselachian muscle as compared with that from an existing
shark, and even the cross striation (lines) of the fibers, character-
istic of the voluntary muscles, as well as the delicate sarcoleijima,
or fiber sheath, is as clearly visible in the one as in the other.

With the passing of time, petrifications may suffer further
change, for the replacing material tends to rearrange its mole-
cules according to the laws of crystals. First, the minute struc-
ture may be destroyed, and ultimately, after an immense lapse
of time, the external form may become modified or obscured
until all trace of organic origin is lost.

(3) Natural Molds or Casts

Another type of fossil consists of natural molds or casts of
the plant or animal, with no trace of the original material re-
tained. Sometimes a shell will be imbedded in sediment which
not only preserves the form of the exterior but that of the
interior as well. Percolating waters may dissolve out the
actual shell, leaving a mold in the form of a cavity, from which
a wax impression may be taken, reproducing the vanished fossil
with admirable fidelity. In this way the skin impressions of
certain dinosaurs have been preserved (Fig. 6). For instance,

* See chart of "Geologic Chronology," pages 46-47.

t See Figure 29 on page 29 of "The Plant World" in this Series.

THE NATURE AND. ANTIQUITY OF FOSSILS 1 1

the animal dies and its carcass settles into soft mud; the latter
takes a perfect mold or impression of the hide with all the details

i'/ the CeoloqicaJ Survey of Canada

*r - . ' *t Un

Fig. 6 THE SKIN IMPRESSION OF CHASMOSAURUS. A HORNED DINOSAUR
It lived in the Great West during Cretaceous time

of its scales or armor. In time, the hide decays and its place is
taken by water-borne sands which, hardening, reproduce in sand-
stone a perfect replica of the exterior of the animal even to the
minutest detail. Thus we have a natural cast comparable to
our artificial one in the case of the shell.

Sometimes, when only a portion of the bone is preserved,
as for example in fossil fishes, or in the Miocene dolphin to be
seen in the Peabody Museum, more can be learned by removing
the bone and taking a cast of the imprints in the matrix than by
studying the ill-preserved bone itself. A classic instance of this
occurred in Pompeii. When it was overwhelmed by volcanic ash
from Vesuvius in 79 A.D., many were the victims, both men and
animals, and later, as their bones were found they were at
first merely dug out, until it was noticed that they lay in cavities
in the hardened ash. The excavators then poured in liquid
plaster of Paris, which, on hardening, was removed and found
to show, with amazing fidelity, the body form and lineaments

FOSSILS

Fig . 7TIIE CAST OF A DOG FOUND IN THE RUINS
OF POMPEII

When the bones of the victims were found to lie in
cavities in the hardened volcanic ash, plaster of Paris
was poured in, which on removal, gave the exact body form

of the features of the
people of Pompeii.
Racial characters of
Roman or Ethiopian,
the garments girded
about the loins, the
expectant mother, an-
other with her child
in her arms all lend
an aspect of reality
which otherwise
would have been lost.
Natural filling in of
the brain cases of
animals and of pre-
historic men endo-
cranial casts has

given us valuable clues to the development of senses and

of psychic characters, which otherwise would have been largely

unknown except by inference.
Even so evanescent

a thing as a jellyfish,

which, as it possesses but

from 1 to 4 percent of

solid matter, soon evap-
orates when cast up on

a beach, may, if immedi-
ately buried by sediment

before the heat of the

sun has destroyed its

form, leave behind as

enduring a mold as a

shell or bone. Many of

these have come to light,

some being of very great

antiquity (Fig. 8).

Famous localities are the

lithographic quarries in

Bavaria (see page 28).

v ';_; - , ''v "" *,.. fci, 1 - Vi**- 1 :;; rtl . " "-

Fig. 8 IMPRESSION OF A FOSSIL JELLYFISH
RHIZOSTOMITES ADMIRANDUS

Found in the lithographic slates of Eichstadt, Bavaria.
The missing parts are restored in outline

(Redrawn from Eastman-Zittcl)

THE NATURE AND ANTIQUITY OF FOSSILS 13

(4) Fossil Footprints and Trails

Allied to the casts and molds are the footprints and trails of
creatures, both vertebrate and invertebrate. Some of the most
ancient indications of animal life are the obscure trails and bur-
rows, presumably formed by worms, in the Proterozoic rocks.
There are also trails of trilobites and other long-vanished
crustaceans, of insects, and above all, of vertebrates, dinosaurs,
and other reptiles, such as the thousands which have been dis-
covered in the Triassic rocks of the Connecticut Valley.

For some reason, with rare exceptions, footprints and actual
bones do not occur together, with the result that the matter of
interpretation of the tracks and of visualizing their makers is
often a problem of great difficulty. Footprints have an alluring
interest, however, for they are relics of the living animals, while
the bones are always those of the dead. If our interpretation is
correct, a single footprint, called Thinopus antiqinis (Fig. 9),
from the Upper Devonian region of Pennsylvania, and now in
the Peabody Museum, is the first indication of a terrestrial air-
breathing vertebrate, antedating in antiquity by some millions of

Fig. 9 THE FOOTPRINT OF THINOPUS ANTIQUUS

On the right is the footprint, supposedly the first indication of a terrestrial air-breathing
vertebrate. On the left is a plaster mold of the footprint showing the same in relief

(After Lull)

years the actual bone remains discovered to date ! It is signifi-
cant in that it marked the emergence of the ancestors of all land-
living, backboned creatures from the old limiting aquatic en-

14 FOSSILS

vironment and thus made possible the peopling of our globe
with the four higher classes of vertebrates, including man
himself.

Accompanying the footprints are often meteorological and

climatic records, sun cracks, ripple marks, and rain impressions

, , _______ , _____________ , (Fig. 10), which enable one to

visualize something of the environ-
ment of the track-makers, if not
the track-makers themselves. As
with molds and casts we get either
the intaglio-like footprint im-
pressed by the animal, or, if it be
the overlying strata, a cameo-like
cast of the -foot in relief; often
both are preserved.

Footprint specimens may be
isolated tracks, or they may form
a series. The latter are the more
instructive, as they not only tell
|b of the size and form of the.foot,
but of the posture, the varied
gaits, and the length of limb;
from occasional handprints of
dinosaurs, the feeding habits,
whether plant or flesh, may be
deduced.

( 5 ) Coprolites

Coprolites are fossil rejecta-
menta often found in association

wlth the ^imals which made them.

The line a-b shows the end of the strand;

und V er '^aler; W^Tnc^a.^ TheSC g IvC Admirable due tO
sand with imprint, of raindrops f eed j ng habits> Thus those Q f the

(After Hitchcock) j i i 1-1 -11 c i

dolphin-like ichthyosaurs of the

Mesozoic are spirally grooved and contain the shells of belem-
nites, extinct relatives of the modern squid. The spiral character is
indicative of the form of the interior of the intestine, while the
belemnite shells show that even in their food these old-time rep-
tiles converged in a remarkable way toward the modern dolphins,

THE NATURE AND ANTIQUITY OF FOSSILS 15

which, being mammals, have succeeded to their role on the
high seas.

The coprolite, associated with the ground sloth Nothro-
therium, of which mention has been made, has been analyzed
with great detail and not only tells us of the food of the sloth,
but thar the nlants of his dav, and. therefore, the climate were

Fig. 11 FOSSIL WORM TUBES (Spirobus
spinuliferous)

From the Devonian period

essentially as they are at present in New Mexico, and, further,
that he died in the spring of an unknown year !

Sometimes, as in certain salamander-like forms from the
Carboniferous strata of Mazon Creek, Illinois, the intestinal
form is clearly outlined in all its windings by the mud that had
sifted in before the organs had perished. Again, under this
head come worm castings, masses of molded sand which have
passed through the worm's intestine and from which the nutrient
matter has been digested. These may be seen on a lawn; they
also cover certain modern beaches in abundance and are occa-
sionally preserved in some of the most ancient sediments.

(6) Artificial Structures

Under this head would come the various implements and
other artifacts* made by fossil man and often accompanying
* Artifact, a product of human workmanship, especially of aboriginal man.

16 FOSSILS

his actual remains, although at times they are the only records
of his existence in certain regions. In the case of the Dune
dwellers in central Mongolia, who have been described by Dr.
Roy C. Andrews, no actual bones have ever been found, but
since the artifacts correspond with those of the Mousterian
culture of Europe, associated with the Neanderthal* man, it is
inferred that the Dune dwellers were similar in age and physical
characteristics.

Turning to the animal kingdom, we find fossil worm tubes
(Fig. 1 1 ) formed of the sand, surrounding the burrow, cemented
together by slime from the worm's body. Caddis worms build
cases of bits of leaves, twigs, sand, or small pebbles, the last two
of which may be found as fossils. This is also true of certain
Protozoa (rhizopods), which build shells of agglutinatedt
foreign particles, sand grains and the like, cemented together
by the slime from their body.

* See page 96.

t Agglutinated, held together as if glued.

CHAPTER III

THE NUMBER AND AGE OF FOSSILS

A CENSUS OF FOSSILS

SO GREAT a number of fossil species has been described in
the literature of paleontology that an attempt to prepare
a census would be an extremely difficult task. And one can rest
assured that the total number of undiscovered forms would
exceed the known ones by a very large majority. Then, too,
the criteria of species, as used by various systematists, vary
so greatly that almost every revision of a group or given fauna
shows results which differ materially from the previously
accepted number; the latter is generally reduced owing to
synonyms or to disregarding as species the endless variations
within a group due to age, sex, or other cause. One must
always bear in mind the vicissitudes to which the strata and
their contained organisms may be subjected; they may be
crushed and folded, or metamorphosed through nearness to
volcanic material; the percolation of acidulated waters may
dissolve away the fossils within them; and finally the rocks them-
selves may have suffered erosion to such an extent that thou-
sands of feet have been destroyed. This last vicissitude may
be local or may extend over vast areas. These, together with
long periods when the lands were worn almost to sea level and,
locally at least, no deposition of sediments could occur, consti-
tute the u lost intervals" during which life must have existed,
but of which there can obviously be no fossil record.

It has been estimated, although to what degree of accuracy
I have no means of telling, that we know perhaps one out of
each thousand of the sorts of creatures of the geologic past.
Naturally the possibility of discovery grows less as one passes
backward to more and more ancient rodts, for the chances of
destruction by any of the several agencies we have discussed are
increased by time.

FOSSILS

Of the number of fossils there can uc no possioie esumate
given, the Yale collection alone containing several hundreds of
thousands, and there are vast areas of limestone and bone con~

glomerate made up almost en-
tirely of organic remains. One
of the largest buildings ever
erected by man, the great pyra-
mid of Cheops, is built of
nummulitic limestone, consisting
largely of the tests* of marine
Protozoa which lived during
Eocene times, the greatest of
which is no bigger than a silver
quarter (Fig. 12). Imagine if
you can their numbers ! Animal
and plant life teems today wher-
ever conditions of environment
permit; so must it have been in
the past, for such is the prodigal-
ity of living organisms that a
region always contains all that
the traffic will bear, and there is
no reason to believe that it has
not been so for hundreds of mil-
lions of years.

It is obvious, therefore, that, with such a profusion of ma-
terial at its disposal, the science of paleontology, due to the
devoted labors of its disciples, has enriched our knowledge of
the past life on the earth in no uncertain way. There is still
much to do upon the material already collected and in our great
museums, some of which is from exhausted localities. What the
rocks may yet yield to our successors in the science no man
can say except that the harvest will be rich.

How THE AGE OF FOSSILS Is DETERMINED

Geologists have been accused of reasoning in a circle on the
ground that they determine the age of the fossils from the
strata, then the age of the strata from the fossils, and there is

* Tests, the external, hard covering of invertebrate animals.

Mg. lli A

LIMESTONE

IMUMMULITIC

Showing the abundance of small fossils.

They are shown here in cross-section. The

famous pyramids of Egypt are built of

this type of material

(Rcdraivn from Eastman-Zittel)

THE NUMBER AND AGE OF FOSSILS 19

sufficient truth in the statement to make the criticism the more
mischievous. The sequence of the strata must first be deter-
mined, which implies, of course, recognition of disconformities
or breaks in the deposition, for manifestly the entire geologic
column with its thousands of feet of sediments cannot possibly
be seen in any one place. Even if the sequence is undisturbed,
as in the Grand Canyon, but a portion of the record, from
Proterozoic through Paleozoic time, is displayed in this most
stupendous section. Generally the lines of demarcation between
successive geological horizons or periods are clearly defined and
indicated by a difference in the character of the sediments, such
as a change from shale to sandstone or conglomerate and often
of color. Again, one horizon may pass into another without
visible break, but a decided change in the contained fossils will
imply a greater or less unrecorded lapse of time.

Having settled the sequence of the strata in a given region,
fossils are sought for, especially such genera and species as are
sufficiently distinctive to be considered "horizon markers. "
Once determined, these serve to identify the age and, therefore,
correlate the rocks containing them wherever they may be
found. Evolution is so orderly a process that not only may one
judge the age of a given fossil, for instance that of a horse,
but he may even predict in advance of their discovery the horses
which should characterize certain intermediate stages and where
they may be sought for in the geologic column, and thus upon
discovery determine the age of the containing horizon. Pre-
dictions such as these have actually been fulfilled in certain strik-
ing instances.

The antiquity of fossils may be determined from several
criteria : By the known position in the geologic column of the
rocks containing them, or, if the particular fossil represents a
form new to science, by certain of the associated organisms
which have previously been identified. One must, however,
guard against the possibility of the intrusion of the specimens
into strata of an older age. This is especially likely to occur
when one is dealing with anything pertaining to humanity, either
his artifacts or his actual bones. Then, too, older strata with
their contained fossils may have been eroded and the material
redeposited. The sediments are often the result of the dis-

20 FOSSILS

integration of older rocks, their fossils showing the effects of
weathering or abrasion by having been rolled in a stream.

STRATIGRAPHICAL GEOLOGY

Strata are often given geographical names, that is, names
derived from the place or region where they are typically ex-
posed and where they were first studied and described. Thus,
the Upper Triassic beds of the Connecticut Valley, which are
equivalent in time to those stretching across New Jersey, Penn-
sylvania, into Maryland, and farther south, are known as the
Newark System, while the Upper Jurassic continental deposits
in the West, which have produced so marvelous a display of
huge dinosaurs, have been known variously as the Como beds
from Como, Wyoming, or the Morrison beds from Morrison,
Colorado, while Professor Marsh* spoke of them as the Atlan-
tosaurus beds because of a characteristic fossil, the great dino-
snur^Atlantosaurus. In like manner the strata at the summit of
the Cretaceous series have been called Laramie, Lance forma-
tion, and Ceratops beds, the last from the horned dinosaurs so
characteristic of them. The modern usage among geologists is to
give the horizon t the first place name which was applied to it in
the geological literature, although the name taken from the domi-
nant fossil has the advantage of being applicable wherever the
horizon with its contained organisms may be found, whereas
place names often seem far-fetched.

Stratigraphic geology has now risen to the ranks of an exact
science, and our modern methods of recording precise horizons
with the most minute subdivisions not only renders more de-
tailed and accurate our knowledge of historical geology, but
also the evolutionary record of life.

*Othneil Charles Marsh (1831-1899), Professor of Paleontology, Yale Uni-
versity.

t Horizon, in geology, the deposit of a particular time, usually identified
by distinctive fossils.

CHAPTER IV

THE LOCATIONS OF FOSSILS

AS WE have seen, a prime condition for fossilization of any
organism is adequate burial before extensive disintegra-
tion sets in. In general, the best opportunities are afforded
where animals are abundant to begin with, and where the de-
positing of sediments is both rapid and varied.

MARINE FOSSILS
The Continental Shelf

The continental shelf, extending from low-water mark to a
variable distance from land, but always to a constant average
depth of one hundred fathoms at its outer edge, is formed
almost exclusively of the waste of the land. The shelf is con-
tinually growing in two directions, shoreward, due to the cut-
ting back of the coast by wave action and tidal scour, and sea-
ward, through the continual carrying out of debris as the waves
recede and by the tidal currents. The shelf is widest on an
old shore, for obvious reasons, but narrow along a newly arisen
coast line. Thus, along the Atlantic coast of North America
it is very wide in places, the Nantucket Shoals, the Georges
Bank, and the Grand Banks being its seaward extension, while
part of the Arctic coast with its great number of islands is also
included. On the newly arising Pacific coast, on the other hand,
the shelf is very narrow. Life teems in the shallow sea over-
lying this area, stimulated by light and warmth, the seasonal
and diurnal climatic change, the unresting motion of the waters,
and the ease of isolation by comparatively small barriers all
of which make for relatively rapid organic change.

In spite of the abundant food, the enormous numbers of
organisms produce great competition and a resulting struggle
for existence, so that these shallow seas have been called the

22 FOSSILS

hotbed of evolution. The constant shifting of old material and
the addition of new causes the sediments to accumulate rapidly,
with a consequent comparatively rich opportunity for burial and
fossilization. Thus shallow water marine organisms form the
great majority of known fossils.

The strand, that area between high and low-water marks,
is less favorable, for strand deposits are trifling beds of sand
and gravel and the contained fossils are, as a rule, only such as
have hard enough shells to withstand the pounding of the surf.
Heavy molluscan shells, more or less broken and abraded, and
the bones of stranded whales would meet one's expectations in
rocks derived from this source.

Deep-Sea Fossils

On the bottom of the deeper seas the rate of accumulation
is almost immeasurably slow, especially in the great deeps, so
that although countless organisms have died in the ocean areas,
the chances of their fossilization when their remains reach the
bottom would not seem to be very great. It is only the more
resistant things, such as the teeth of sharks and the ear-bones of
whales, that stand much chance of preserval. These are repeat-
edly dredged from the great deeps where they lie apparently
exposed. As a matter of fact, however, we know very little
about the deep-sea deposits from actual observation, for only
rarely have they been brought up from the deeps by natural
agencies and so have come within our scrutiny. Indeed, there
are but two localities that have been generally accepted as bona
fide examples of material formed in the great deeps. These
are in Trinidad and Barbados and again in the islands of
Timor and Rotti in the Dutch East Indies. In the former
region there is a coral formation under which lie 250 to 300
feet of chalky and siliceous earths with clays of various colors
and volcanic mud. The siliceous earths are composed largely
of the shells of minute Radiolaria and under the microscope
appear very like the deep-sea oozes which are obtained by
dredging (Fig. 13).

The East Indian beds in Rotti Island contain manganese
nodules as well as those of chert (flint), which are full of
radiolarian shells in the siliceous limestones and shales, while

THE LOCATIONS OF FOSSILS

I ' E

Distcphns rotundis Ptcrocodon campana Pctalospyris corona

Fig. 13 A GROUP OF RADIOLARIA

1 and 2, from the Tertiary era of Barbados; 3, from the tripolite of Groth
(Redrawn from Grabqu)

in the beds in the Island of Timor, in addition to the manganese
nodules, there are a great many sharks' teeth and radiolarian
remains in the clayey shales. The sharks' teeth are from the
genus Lamna and are comparable in condition to those dredged
from the deep-sea red clays by the British exploration ship
Challenger and by other expeditions.

In the Island of Celebes, in the Malay Archipelago, there

Fig. 14 A PHOTOGRAPH OF SOME GLOLUGER1NA OOZE
This tiny animal is important as a limestone builder

24 FOSSILS

are Cretaceous shales containing the organisms known as
Globigerina, which cover thousands of square miles in the At-
lantic and elsewhere today, at an average depth of 1500 to 2500
fathoms (Fig. 14).'

Estuarine Deposits

Estuarine brackish-water deposits at the mouths of certain
great rivers form more quickly, and here the conditions are much
the same as they are on the continental shelf, except that the
silting up, save in the actual channels, may be much faster. Here
sea and fresh water meet, and the rivers checked in their rapid
action, throw down their burden of sediment. The annual ex-
penditure of millions of dollars to maintain harbors and chan-
nels at navigable depth points to the rapidity of accumulation.

River Bars and Deltas

River bars with shifting sand banks, even where no estuary
exists, are due to the same cause, for flowing water can carry a
burden which increases with the square of its velocity. Check-
ing of the river's speed at once reduces its carrying power and
the load is deposited in proportion. Some rivers where the
amount of sediment is normally great, such as the Mississippi
and the Nile, have built out great deltas into the sea. Such
deltas when explored for fossils are apt to be highly productive,
generally of the remains of land animals and plants or forms of
fresh water origin.

There may, however, be occasional marine deposits intro-
duced between those of fresh water origin, due to wave action,
or to periods of extremely high water, which sometimes result
from a combination of strong on-shore winds and the spring
tides \^hich occur at new and full moons. These interpolated
beds may contain marine shells. In parts of the Rhone delta,
France, marine and fresh water shells alternate; the same is
true of the lower deposits of the Po delta in Italy, the upper
ones being entirely marine. The deltas of the Ganges in India
and of the Zambezi in Africa contain the remains of river
animals, turtles, crocodiles, and hippopotami, as well as ter-
restrial creatures such as antelope, buffalo, lion, and other mam-
mals, victims of drowning brought down by the stream.

THE LOCATIONS OF FOSSILS 25

Old Inland Sea Bottoms

Certain shallow seas, such as that which covered the vast
interior of our continent during Cretaceous time, have left hun-
dreds of feet of marine sediments. Among these a widespread
chalk bed is of especial interest, since it has given us a very com-
plete knowledge of fishes, marine reptiles, such as mosasaurs,
plesiosaurs, and turtles, flying reptiles or pterodactyls, of which
Pteranodon with a wing spread of upward of twenty-five feet
was Nature's greatest flying creature, and finally the toothed
birds, Hesperornis and Ichthyornis. This, the Niobrara forma-
tion, is classically displayed in Gove County, Kansas.

TERRESTRIAL FOSSILS
Flood-plain Deposits

Of strictly continental deposits, great areas of Cenozoic
rocks, with their contained river reptiles and land mammals,
are to be found in western United States. These were formerly
looked upon as lake deposits, and names such as Bridger Lake
and Uinta Lake are frequent in the older literature. But many
of the animals were found far out from the assumed shore,
sometimes in great abundance. The rate of deposition on a
large lake bottom is normally extremely slow and would not
account for the thickness of the strata accumulated in a com-
paratively brief time. So the old idea has been abandoned in
favor of a belief that these represent river flood-plain deposits.
The law of the carrying power of water obtains here. A river
during time of flood is turbid with sediment, but as it overflows
its banks, as the Mississippi did during the disastrous floods of
1927 when in places it reached a width of one hundred miles, its
rate of flow is checked outside of the main currents of the stream,
and the load thrown down. Obviously during such times, casual-
ties to animal life and easy and rapid burial are proportionately
accelerated with a comparable increase in resultant fossils.
These in turn are rendered accessible by subsequent erosion.
Collectively, the flood-plains produced by many contemporane-
ous rivers would give the impression of lake deposits of vastly
greater area but would lack the continuity of the latter, except

FOSSILS

where the rivers were confluent. Actual lake deposits must be
of comparatively little importance, at any rate from the stand-
point of preserving land faunas.

Peat Swamps and Quicksands

Peat swamps and quicksands, although not so extensive as
other deposits, have nevertheless preserved some very interest-
ing animals of which we might otherwise know little. It has

Fig. 15 PAKT OF THE GREAT ACCUMULATION OF BONES AT THE KANCHO
LA BREA NEAR LOS ANGELES, CALIFORNIA

These animals were victims of an asphalt pool during Pleistocene time

been said that nearly every peat swamp of Pleistocene time in
eastern and central United States contains at least one mastodon
skeleton, and there have been recorded at least 219 occurrences
in the peat swamps of New York State alone.

Quicksands, which at other seasons may be quite innocuous,
become terrible traps for the unwary during times of abundant
rains or floods. These, as in the case of swamps, bury as they
slay, so that the resultant fossils are practically intact. Specific
localities wrll be discussed later.

THE LOCATIONS OF FOSSILS 27

Coal Swamps

Of course, the widespread, low-lying coal swamps formed
during Carboniferous times, with their abundance of plant life,
are of the utmost importance. For the coal itself is the con-
solidated plant material, carbonized and more or less metamor-
phosed in the different grades of coal, least in the lignite or
brown coal, and most in the anthracite. The animal remains
are rarer, but we have learned much of the insects, fishes, and
amphibians which were denizens of the Carboniferous swamps.

dsphalt Beds

A very remarkable, though unusual, condition for fossiliza-
tion is found in asphalt, one of the most famous localities being
the Rancho la Brea near Los Angeles, California (Fig. 15). The
California oils differ from those in the East, for whereas in the
latter the ultimate solid residue, after distillation, is paraffin wax,
in the former it is asphalt. Here the oil wells up from below
through natural pipes and spreads over the ground. The lighter
and more volatile products gradually escape, and the remainder
becomes more and more viscid, ultimately drying out, especially
toward the outer edge of the flow. This becomes covered with
wind-blown dust, and hence its real character is concealed. Some-
times, particularly after rains, there may be standing pools of
water. A thirsty animal, attracted by water, would venture
across the concealed asphalt, and for a while all would be well
until he approached the softer portion toward the pipe. Then
he would break through, and his efforts to escape, for the
asphalt is appallingly sticky, would only render his plight the
worse. To this day the death trap is in operation, for every
now and then wild and domestic animals and birds are caught
and engulfed.

During the Pleistocene period there lived an amazing as-
semblage of animals in western America, and occasionally a
large herbivore elephant, ground sloth, horse, or camel would
be caught and act as a living bait for wolves, coyotes, sabre-
tooth cats or vultures and other carnivorous birds, who sought
to prey upon them. As a rule, carnivores are rare as fossils,

FOSSILS

for they* usually consist of a comparatively small proportion of
the total numbers of any fauna. But here they are largely in

16 A RESTORATION OF THE SABRE-TOOTH TIGER, SMILODON

Whose skeleton was found in such abundance in the famous asphalt pool at Rancho

la Brea, California. This pool formed a natural trap in which various Pleistocene

mammals and birds were caught and engulfed

Drawn from the Yale Pcabody Museum specimen restored by the author

excess, no fewer than 700 skulls of the sabre-tooth tiger
(Smilodon] having been recovered (Fig. 16). The asphalt
tends to work so that the bones are pulled apart, and one never
finds a skeleton in articulation;* but the individual bones are
splendidly preserved.

SOME FAMOUS LOCALITIES OF FOSSILS
Solnhofen, Bavaria

A world renowned locality which has produced fossils, not
only in marvelous degree of preservation, but in many instances
of unique scientific value, lies in Bavaria. Here the deposits
are marine, of Jurassicf age, and in the form of large limestone
reefs, the lowermost composed of the remains of sponges, some
of great beauty. The later reefs, on the other hand, are formed
of calcareous algae J (lime secreting sea-weeds) and countless

* Articulation, joined together.

t See chart of "Geologic Chronology," pages 46^47.

t See page 13, "The Plant World" in this Series.

THE LOCATIONS OF FOSSILS

examples of a large bivalve shell. Between the reefs were
lagoons, the floors of which were covered with a fine limy ma-
terial, the result of wave action on the reefs themselves, which
broke off portions and ground them into a fine, gritless mud.
These lagoon sediments now constitute the stone used so largely
in the art of lithography a generation or so ago. The layers
of this lithographic stone average some six inches, the beds
being separated by a more clayey material. Animals dying in
the lagoons would sink to the bottom where the fine muds would
bury them and preserve their remains with wonderful fidelity.
The lithographic quarries, especially at Solnhofen and Eichstiidt,
aside from their commercial output, have greatly enriched our
collections and consequently our scientific knowledge of the
faunas of the Upper Jurassic time. Obviously, the greater
number of the animals were of marine origin and had their being
in these seas, but there were land-living creatures as well, which,
however, with rare exceptions, were
capable of flight, such as dragonflies,
pterodactyls or winged reptiles, and
true birds, which winged their way over
the lagoons in search of prey.

Among marine animals are the im-
pressions of jellyfishes and specimens of
Crustacea of various kinds, allies of the
existing horseshoe crabs (Fig. 17),
squid, and cuttle-fish, some with the
sepia still preserved in their sacs, from
which during life they could emit a cloud
of inky fluid analogous to the smoke
screens used by ships during the World
War, and finally fishes of many kinds.
There were also turtles and crocodile-
like forms. Of the flying reptiles, some,
like the famous specimen of Rhamphor-
hynchus phyllurus treasured at Yale
(Fig. 44), have preserved impressions
of the wing membranes with their finest
wrinkling, as well as of the rudder-like
expansion on the tip of the tail. But per-

Fig. 17 ITORSE-SHOE
CRAB, LIMULVS

One of the many creatures
found in the Jurassic deposits ot
Solnhofen; their survivors are
still common along the seashore

FOSSILS

haps the most notable of all is the Archaeopteryx, the first bird
known to geological history (Fig. 46). Three specimens of this

Fig. 18 A CAST OF COMPSOGNATHUS LONGIPES, THE SMALLEST
RECORDED DINOSAUR

It was about two and a half feet in length, with the bulk of a domestic cat. It was
found in the famous Solnhofen Quarry in Bavaria

From a photograph of a cast in the Yale Peabody Museum

genus have been found, one a single feather discovered in 1860,
another a headless bird (1861), now preserved in the British
Museum of Natural History, London, while the third, found in
1877 near Eichstadt, practically complete, head, feathers and
all, is now in Berlin.

THE LOCATIONS OF FOSSILS

Yet another remarkable find was the smallest known car-
nivorous dinosaur, Compsognathus longipes, about the size of
a house cat (Fig. 18). How this creature ever drifted so far
from its natural habitat as to be entombed in one of these ancient
lagoons one cannot imagine. Of terrestrial vertebrates there are
15 genera and 42 species; of invertebrates and aquatic verte-
brates the grand total, except for the insects, is 150 genera and
350 species, of which 88 genera and 175 species are limited
to the Solnhofen region and have been discovered in no other
locality.

Agate Spring Quarry, Nebraska

This noted locality lies not far from the railroad town of
Harrison, in Sioux County, Nebraska. Here, on the south side
of the Niobrara River, rise two hills, remnants of a more exten-
sive series of sediments which have been largely worn away.
The fossil-bearing horizon is nearly horizontal and extends
through both hills. The thickness of the deposit varies from
three to twenty inches, the bones toward the bottom being more
or less worn and rounded, indicating either longer exposure or
farther transportation before they reached their final resting
place.

In the larger of the two hills the fossils are in such
remarkable profusion in places as to form a veritable pave-

Fig. 19 THE SMALL TWIN-HORNED RHINOCEROS, DICERATHERIUM

Whose skeletons were found so abundantly in the Agate Spring Quarry
Prom a restoration by the author, based upon the skeleton in the Yale Pcabody Museum

FOSSILS

ment of interlacing bones,
very few of which are in their
natural articulation with one
another.

In order of numbers there
is first the small twin-horned
rhinoceros, Diceratherhim
(Fig. 19), then the strange
clawed ungulate Moropus
(Fig. 20), of which the
American Museum collected
seventeen skeletons, complete
or nearly so. The rarest ani-
mal is one of the giant swine,
Dinohyus (Fig. 21), a crea-
ture with a skull a yard long,
and standing six feet at the
withers (the highest point be-
tween the shoulders).

Some miles farther to
the east is another quarry of
approximately the same age
(Miocene period) , which con-
tains remains of the beauti-
ful gazelle camel, Stenomylus

Fii?. 20 THE STRANGE CLAWED
UNGULATE, MOROPUS

Also from the Agate Spring Quarry

From a restoration by the author, based
upon the skeletons in the American Mu-
seum of Natural History and in the Yale
Pcabody Museum

Fig. 21 THE GIANT SWINE,
DINOHYUS HOLLANDl

Also from the Agate Spring Quarry.

It had a skull a yard long and stood

six feet at the withers

From a restoration by the autJior,

based upon the skeleton in the

Carnegie Museum

THE LOCATIONS OF FOSSILS

(Fig. 22), some of the skeletons completely articulated, others
disarticulated. Here, out of half a hundred individuals collected
by parties from Amherst College, Yale University, the American
Museum, and Carnegie Museum, all pertain to this one species
save a single skull of a huge wolf-like carnivore, probably a

Fig. 22 A GROUP OF (JAZEFJ.E CAMELS (Stenomylus)

Collected by the author and mounted in Yale Peabody Museum. These skeletons, along
with forty others, were found near Agate Spring, Nebraska. Such a profusion of
skeletons belonging to the one genus, and the fact that there was only one other asso-
ciated skeleton, lends to the belief that these were all victims of a common disaster

fellow victim of a common disaster. In both instances
the deposits are river sands and seem to represent large coves
in the back waters of which the carcasses found lodgment after
drifting down stream from the place of catastrophe, wherever
that may have been. An alternative view, that of quicksands
at the bottom of a pool in which the creatures were engulfed
when they came for water, might be held, and the confusion of
the bones lends weight to this theory, for the sands shift and
move, as did the asphalt mentioned above, and pull the skeletons
apart.

It is difficult now to determine the former extent of these
deposits, for much natural erosion has occurred, but they were

34 FOSSILS

surely local and exclusive and do not begin to include the total
numbers of species which inhabited the region during Miocene
times.

The profusion of individuals from the Agate quarries may
be judged from a single block now in the American Museum
(Fig. 23). This block measures 5^x8 feet, and contains twenty-
two skulls and an uncounted number of skeletal bones. As these
average 198 bones to an animal, there may be at least 4356 bones
in the block of forty-four square feet, or ninety-nine to the square
foot.

The Carnegie Museum has excavated in addition 1350
square feet, which have yielded 164,000 bones or 820 skeletons.
Based on this yield, the estimate of the number of animals in
the entire hill is:

Diceratherium 16,400 skeletons
Moropus 500 skeletons

Dinohyus 100 skeletons

Mount St. Stephen Region, British Columbia

An amazing discovery by Dr. Charles Doolittle Walcott
(1850-1927), late secretary of the Smithsonian Institute, on the
side of Mount Wapta, British Columbia, disclosed a small area
of dark shale on which were impressed as a film of carbon the
most delicate parts of fossil animals of lower Cambrian time.
These consisted of jellyfish, worms of various sorts, sea-cucum-
bers, and trilobites, all with appendages, traces of the gut, and
other internal structure preserved with the utmost accuracy.
These were creatures which lived upward of 500 million years
ago, and on top of the sediments which bear them there were laid
down several miles of thickness of strata which were solidified
into rock and the whole mass elevated by crustal movements into
mountain masses and later eroded to form the mountains' and
canyons.

At the locality where Dr. Walcott found his specimens, sub-
sequent erosion had removed the overlying rocks to the precise
level of the older formation, when by fortunate chance the keen
eyes of the geologist discerned the impressed organic remains.
It is a matter greatly to be wondered at that such fragile organ-
isms should have left any traces whatever, but that they should

THE LOCATIONS OF FOSSILS

be so perfectly preserved and have survived the subsequent
vicissitudes to which they have been subjected the mighty

Courtesy nf flic Aniencan

f Natural Jfisforv

Fig. 23 A SLAB FROM AGATE SPRING QUARRY

The profusion of bones may be judged from this picture of a single block now in

the American Museum of Natural History. This block measures 5$ x 8 feet, and

contains twenty-two skulls, and an uncounted number of skeletal bones

mountain forces, the crushing weight of the thousands of tons
of overlying rock, and the elements which led to its later removal
,as well as the final discovery of the small locality, are a series
of happy accidents which seem almost providential. The odds
are so immeasurably against such an event that its duplication
will probably never occur.

Such revelations, however, lead to a very optimistic hope
that, in spite of the present limitations of our knowledge, our
successors in paleontological research will one day be able to
reveal the continuity of life, in all of its varied ramifications, with
a high degree of perfection and detail.

Bone Cabin Quarry, Wyoming

Yet another famous locality is Bone Cabin Quarry, where the
author had his initiation into the mysteries of field technique.
It lies about twelve miles from Medicine Bow, Wyoming. This
is in deposits known as the "Morrison" formation, of Upper
Jurassic age. The outcrop consisted of weathered fragments
of limb bones and vertebrae of the giant dinosaurs of that time.

FOSSILS

These covered the ground in such profusion that a sheep herder
used some of them to huild the foundations of his hut, hence the
picturesque name of the quarry.

The region, now over 6000 feet above the level of the sea,

Fig. 24 BONE CABIN gUAKKY IN 1899, WITH THE BONES OF
BRONTOSAURUS PARTLY EXPOSED

From a photograph by the autlwr

was once low-lying, and the sediments were the accumulations
near an ancient shore line or the sloping bank of a muddy
estuary or lagoon. Here the dinosaurs must have lived, not far
from the place where they lay buried. Rarely does one find an
approximately complete skeleton; the remains consist largely of

THE LOCATIONS OF FOSSILS 37

articulated limbs or tails or possibly the neck which must have
been held together by the strong ligaments and tendons after
the partial dismemberment of the carcass (Fig. 24). The fragile
skulls, on the other hand, are very rare. In the neighboring
Como Bluff, however, more complete skeletons have been brought
to light, notably the great Brontosaurus and the grotesque Stego-
saurus now mounted in the Yale Museum. Bone Cabin Quarry,
after several years of excavation, is by no means exhausted, but,
on account of the dip of the strata beneath the surface of the
ground, it'can no longer be worked profitably except on a large
and expensive scale. The American Museum has recovered
from it 483 parts of animals weighing in all nearly 100,000
pounds. These represent forty-four large amphibious dinosaurs,
three armored dinosaurs, four unarmored bipedal ones, six large
and four small carnivores, four crocodiles, and five turtles. Dr.
Henry Fairfield Osborn says that this is not one-half the total
number, and that in all probability the locality would produce
parts of over a hundred giant dinosaurs.

South Joggins, Nova Scotia

In certain horizons of the coal fields of South Joggins, Nova
Scotia, tree trunks have been found which are buried in an erect
position in the very spot where they once grew. These tree
trunks, the largest of which is nine feet tall, as preserved, range
in diameter from one to nearly three feet and represent the
sturdier among the trees of an ancient forest of Carboniferous*
time. \They ^arejoftenjvell_rooted in the^ ancient .snil^ _and haye
been preserved byi^die.-a^udajtions_of co^L^ruLdaySu ahaye.it.
They are largely^jcale_trejes,_5^i//^n^,which after dying, were
broken off, jind, the interiox having decayed^ only the outer riod
is now preserved. _

Tliey are interesting not only asiossils of that ancient wood-
land, but even more so fromjheir_c0ntents, fo_r the broken sum-
mit was for a time at .least, level with the accumulated soil, jhe
hollow within appearing as a, welLor J?5t into which snails^ and
millegedes^ could crawl, 4^y~taxlie^aiuLbe buried inj:h muddy
clay that gradually filled the cavity. Yet more remarkable is
the f acFThaT" thesF"tTb1TowrTormed veritable death traps for

* See chart of "Geologic Chronology," pages 46-47.

38 FOSSILS

small quadrupedal vertebrates, amphibians belonging to the
order Stegocephalia, and others remotely related to the living
salamanders. The sediments within the trunks change in char-
acter from time to time, indicating that the hollows were a con-
siderable while in filling. In all about fifty-three specimens,
including a dozen species, have been recovered from fifteen out
of the twenty-five trees which have been catalogued. ~^

ARE FOSSIL REMAINS STILL BEING DISCOVERED?

The amazing success of the American Museum expeditions
to Mongolia under the leadership of Dr. Roy Chapman An-
drews, emphasizes the fact that the world is not yet fully ex-
plored and that vast areas still remain to be systematically
searched for fossils. Chinese fossils have been known for years,
but as they had, in the eyes of the natives, a high medicinal
value, one rarely saw them unless in an apothecary's shop where
their scientific significance w r as entirely ignored.

In fact, the fate of the specimen was ultimate destruction,
for a whole rhinoceros tooth would be a hard pill to swallow,
but when powdered in a mortar and mixed with other ingredi-
ents it would perhaps be no worse to take than many of our
modern medicines. This use of fossils, based upon what we are
prone to call Chinese superstition, has its parallel in European
medieval and later medicinal practice, notably in the use of the
unicorn's horn, really the tusk of the narwhal. So high a value
was placed on this that a specimen in Dresden was estimated in
the sixteenth century to be worth $75,000, and only the very
rich could afford its use as a medicament. The artificial value
placed upon fossils in China, due to their supposed healing
virtues, has retarded the work of science, but it indicated the
possibilities of the country, especially of central Mongolia,, as a
fossil field, an indication which has been abundantly justified.

It was scientifically a virgin country and has given us animals,
not only abundant and perfect, but often entirely new to our
paleontological lore. The same was true of western United
States in the eighteen seventies and eighteen eighties, when not
only new species and genera, but unheard of families and orders
were continually coming to light. These have greatly enriched
our science and especially the collections of our great museums.

THE LOCATIONS OF FOSSILS

The western localities are not now as visibly productive as
they were in those days, for the surface indications which were
formerly so numerous have largely disappeared through the zeal
of many collectors, but undoubtedly the strata are still rich in
material which will one day, through erosion, reappear. Cer-
tain localities have been entirely exhausted for invertebrate
fossils, and the col-
lections made from
them have a corre-
spondingly increased
value to museums,
although the new
scientific information
which they have
revealed has been
largely published. It
is safe to say that
the rocks have by no
means yielded all
their secrets and that
the science of paleon-
tology will continue
to flourish for gen-
erations to come.

The most pro-
ductive horizons for
invertebrate fossils are the shoal water sedimentary rocks, and
these may be found everywhere along the sea cliffs, in railroad
and other cuttings, along the Niagara Gorge, the Grand Can-
yon, or wherever these rocks are exposed. Marine vertebrates
may also be found under like conditions, but for terrestrial
vertebrates, preserved in the continental deposits, the greatest
opportunities lie in the semi-arid parts of the earth, in western
United States, the Patagonian pampas, the Faiyum desert of
Egypt, South Africa, central Asia, and, as a likely though unex-
plored area, central Australia. In such areas as these there
is little vegetation to obscure the geology and in nearly every
case there has been extensive erosion due to the occasional tor-
rential rains and the lack of a protective mantle. In the more

Fig. 25 THE FOSSIL FISH, PHAREODUS ACUTUS

An excellent specimen from the Eocene strata of Wyoming

(After Schuchert)

40 FOSSILS

humid regions the overlying soil six feet or more in New
England, sixty feet in Brazil not only covers up the actual
strata but is largely the result of the disintegration of the
rocks themselves together with their contained fossils. The
explorations in Mongolia, to which we have already alluded,
have merely scratched the surface along certain narrow lines
of march. But even so, the results have been remarkably rich.
A widespread intensive survey conducted by many parties over
the entire area would produce returns which cannot be esti-
mated and much of which would be new to science. For species
are often extremely local in their geographic distribution, and
the reconnoissance work already done may well have passed by
the haunts of curious and unusual bygone forms.

CHAPTER V

FOSSILS AND THE THEORY OF EVOLUTION

SINCE all animate nature represents a single great evolution-
ary process and that is the only logical explanation which
can be offered for its existence it is evident that the true story
of the continuity of life can only be displayed in its entirety by
combining in one series all the evidences of animal life, whatever
their age. The existing forms alone would not serve, for while
Nature has preserved alive representatives of the most archaic
as well as of the most recently evolved organisms, there are
extremely important groups graptolites, trilobites, ammonoids,
as well as a marvelous array of vertebrates, stegocephalians,
dinosaurs, and others, which have been entirely blotted out and
have left no descendants in the living fauna of the globe. On
the other hand, many existing creatures, some of which have
no hard parts, such as the naked protozoan, Ameba, and which
we assume to be ancient because of their simplicity of organiza-
tion, are practically impossible of fossilization and, therefore,
are unrepresented in the paleontologic series. It is only by an
inclusive arrangement that a right conception of animate nature
becomes possible, if one would view the evolutionary process as
a whole.

It is evident, therefore, that the fossils reveal to the sys-
tematist and evolutionist much that existing nature cannot show.
Who, viewing the lordly elephant with its ponderous bulk carried
on four massive limbs, its distinctive proboscis and tusks, would
see in it any community of origin with a Florida manatee with
its fish-like form, split prehensile lips, propelling tail, flipper-like
fore limbs, and no hind limbs at all? And yet the Faiyum
region of Egypt has revealed fossils, clearly the ancestors of
both elephant and manatee, the skulls of which are so alike that
in some instances, notably that of Moeritherium, the highest
authorities were for a while of divided opinion as to which group

42 FOSSILS

it belonged, the proboscidean or sirenian. Thus paleontology
aids the systematist in his search for relationships which the
modern animals could not possibly reveal.

The three main lines of evidence for the evolution of any
group of animals are comparative anatomy, ontogeny, and
phytogeny. In the first one studies structure and form, dis-
tinguishing between what are called homologous organs. Such
are the fore limbs of vertebrates, and distinction is made between
them as to whether they are grasping organs like our own, run-
ning organs as in the horse, paddles for swimming as in the
whales, or wings as in the bird. The basic structure is the same
in all, but variety of use has produced dissimilarity of form.
A comparative study will at once reveal how in each instance
the ultimate adaptation to its peculiar function has been brought
about. But no one would attempt a structural comparison of
the wing of a bird and that of a butterfly, although their use is
precisely the same. They are analogous organs in their simi-
larity of function but are in no sense homologous, implying
a correspondence in origin, for the wing of the bird is a modified
fore limb, whereas that of the butterfly is an outpushing of the
body wall which has become greatly expanded, movably articu-
lated, and endowed with muscles. One could not by any stretch
of the imagination derive the one wing from the other, nor does
the possession of the common property of flight indicate the
slightest trace of relationship between their possessors.

Ontogeny is the life history of the individual, from the begin-
ning of its life as an independent cell, derived from its parents'
substance, to its death, or, in the case of the potentially immortal
one-celled organisms which pass all of their body substance as
well as their life to the offspring, it ends with their loss of
individuality. Man starts as do other organisms, as a single cell,
which, through cleavage, develops into a multicellular being the
parts of which are at first all alike. Later there occurs differen-
tiation in form and function by means of a physiological divi-
sion of labor, the embryo passing through ( 1 ) a stage in which
segmentation appears and a backbone is indicated, (2) a fish-like
stage with gill-clefts in the neck, (3) a stage like an amphibian,
(4) others like a primitive reptile, a generalized mammal, and
a primate, respectively; finally there appears a miniature man.

FOSSILS AND THE THEORY OF EVOLUTION 43

All of these marvelous changes, wrought in the first few
weeks of prenatal life, are thought to parallel roughly the actual
evolutionary changes through which man's ancestors passed dur-
ing a period of hundreds of millions of years of geologic time.
The celebrated German savant, Ernst Haeckel, first formulated
what is known as the Biogenetic Law* based upon this principle,
although apparently he was not the first to conceive it. It has
not universal acceptance among scientific workers today, yet few
will deny that individual life-history is one of the proofs of
evolution even though, because of the vicissitudes of individual
existence and the consequent need of meeting new conditions
during the process of growth, a precise parallel between
ontogeny and racial history is hardly to be expected.

The third proof of evolution lies in the actual documentary
evidences of racial history, or phylogeny, as it is called. Rarely
can these be obtained among existing organisms, although some
phyletic lines in which change is going on rapidly enough for
human observation are actually on record. The wonderful
modifications which man has wrought in domestic animals and
plants through selective breeding are of a comparable sort,
and, though largely the outcome of artificial conditions, yet
Nature as well as man has had a hand in their production. At
all events they show the wonderful plasticity of living beings,
and if in the hands of man, why not in the hands of a vastly more
powerful Nature? At any rate man's methods are analogous to
the process of natural selection and were of the utmost im-
portance to Darwin in the understanding and definition of
natural selection itself.

Evolution is, as a rule, an extremely deliberate process;
Nature has all she needs of time and circumstance for its fruition,
and as a rule the brief time allotted to the individual for his
observation is all too little for the purpose. It lies, therefore,
within the scope of one whose backward vision has certain ele-
ments of immortality to gain a full conception of the phylo-
genetic process. For not only can such a one visualize past con-
ditions of land and sea, of climate and the various phenomena

* Haeckel's Biogenetic Law may be stated as follows : The life history of
the individual (ontogeny) gives a brief resume of the evolutionary history of the
race (phylogeny).

44 FOSSILS

of the physical environment, but he can also see the march of
organisms through time. For the last his documents are the
fossils. Thus they occupy a position in science held by no other
group of phenomena, for they provide the final proof of the
process of evolution, and there is no other explanation which
can possibly account for them.

Paleontology is, therefore, the final court of appeal to test the
truth or falsity of the growing belief in evolution. All that is
necessary is as adequate a series of fossils as possible for the
determination of their sequence, and the correct interpretation
of what they represent, for their teaching is one that cannot
intelligently be gainsaid.

CHAPTER VI

PLANTS AND ANIMALS OF THE PAST

EVEN a brief description of the evolution of the entire animal
kingdom as set forth in the fossil records would fill many
times the allotted pages of this book. One must, therefore,
after a general summary, turn to certain groups wherein the
fossil series is remarkably complete, referring the reader to
more extended works for further instances and greater detail.

THE PALEOZOIC ERA
The Cambrian Period

The earliest evidences of life are extremely meaner, passes
of limestone and graphite and very few obscure fossils arc all
we have as evidence, either direct or indirect, of life during the
first two eras,* the Archeozoic and Proterozoic, which together
constitute over one-half of geologic time as recorded in the sedi-
mentary rocks of our earth. With the ushering in of the Paleo-
zoic era, in its initial period, the Cambrian, the lime-secreting
jiabit is acquired, and now for the first time there are clearly un-
derstandable fossils. They represent, however, all of the great
invertebrate phyla t whose evolution is thus implied, even though
unrecorded, in the preceding eras. Cambrian animals are all
marine, showing that the seas were their initial home and that
presumably fresh waters, and certajnjyjthelands, were yet tenant
less.

These old forms included sponges, corals, worms, trilobitcs,
and the like (Figs. 11, 26, and 27). As vet there is no trace of
backboned animals. Vertebrates may well have had their origin
guring Cambrian time, hut- if will require "lucky" accidents oi
preserval and discovery, such as in the Mount St. Stephen

* See chart of "Geologic Chronology," pages 46-47.

t Phylum, plural, phyla), a limb; see page 42, "The Coming and Evolutior
of Life," in this Scries.

n,
^

Cft

G CHRONOLOGY*

Lull, Organic Evolution)

ADVANCES IN LIFE

IAN REVOLUTION

Extinction of Great Mammals

Origin of Man

Culmination of Mammals

Rise of Higher Mammals

Extinction of Archaic Mammals

Rise of Archaic Mammals

[DE REVOLUTION

Extinction of Great Reptiles
Specialization of Great Reptiles
Rise of Flowering Plants

O
C

C/5

o
.2

D
C

<L>

C/3

^K S

i-3 -d

<d*

O -3

."2

*>.2

</3

1> QJ

.ii

(/} rt

CtJ
4-1

.53

4-1

CL -q

L
i

j ^

3 '^

U It

^ *

5 ^

N ~<

3 fe

Cfcj

ffi

J !

-i O

u ^

O !

> T-

1 1

C/5

; *

-1

Crt

jrt

cS^ 1

J*5?-

l-g

u c3

S"w fe

-S o3

'5 w

"^ c

53 1

i-j

^~^

JCO

AN REVOLUTION

tinction of Much Ancient

se of Primitive Reptiles an

J-.

IS c

p, CTj

"jj

bo {

Rise of Land Plants and Cor
Rise of Armored Fishes

^Rise of Shelled Animals
First known Marine Faun

VTON REVOLUTION

."2

:C HISTORY

i ^^
2

ft
S!

g'S

'g^

'
o

Cambri

25 <

ROTEROZOIC

25%

ARCHEOZOIC

30%

1
U

FOSSILS

Quarry, to disclose them, because of their probable soft-bodied

:haracter.

dominant life of the Cambrian,_by which we mcannQt

necessarily the high-
est in the evolution-
ary sense, but the
forms which by thefr

Courtesy of Dr. Carl Dunbar

Fig. 26 THE CHAIN CORAL, II A LY SITES

Characteristic of the Silurian era; an example of a
pseudomorph in which the original lining material has

been replaced by silica

profusion and power
seem to have the
ruling position, were
doubtless the trilo-
Tjjtes (Fig. 27)~!
T h e s e crustaceans
are remotely related
to the shrimps, the
lobsters, and the
crabs of today. They
had a resistant up-
per shell covering
head and body but apparently a soft lower surface and ap-
pendages, for the latter are rarely preserved. They were
generally crawling forms, inhabitants of the sea bottom, but
probably had the power of swimming in a somewhat jerky way.
Some groveled in the mud for food, others were more actively
predacious, and, al-
though most of them
had well developed
eyes, a few were blind
as though they dwelt
below the limit of sun-
light, or more prob-
ably, were nocturnal in
habit, since most of
their remains come
from shallow water
deposits.

By Upper

brian time the trilo-
bltes haddevelopedthe

Fig. 27 TRILOBITES (natural size)

They formed the dominant life of the Cambrian period.
They were generally crawling forms, inhabitants of
the sea bottom, but probably had the power of swim-
ming. By Upper Cambrian time they had developed
the habit of coiling up for defense

From specimens in the Yale Peabody Museum

PLANTS AND ANIMALS OF THE PAST

habit of coiling up for dcfense T after the manner of armadillos.
In size the trilobitcs ranged from a fraction of an inch to 27 j
inches. Trilobites are ancestral, either directly or indirectly, to
all other arthropods crustaceans, scorpions, spiders, millepedes,
and even the insects. The Cambrian has been known as the
Age of Trilobites.

The Ordovician Period

In Ordovician time, land plants probably arose, having their
origin in certain marine algae which gradually crossed the
strand, becoming
more and more in-
ured to an air in-
stead of an aquatic
environment. Per-
haps the most char-
acteristic single
group of marine
fossils of the Or-
dovician are the
graptolites, so
called from their
resemblance
to some sort of
writing on stone.*
These were colo-
nial organisms be-
longing to the coe-
lenterate phylum
which includes also
the polyps and
jellyfishes and is
therefore low in
the scale of inver-
tebrate life. Of
the graptolites, the
actual polyps are
not preserved, but

Fig. 28 GRAPTOLITES

The most characteristic group of marine fossils of the
Ordovician period. These were colonial organisms belong-
ing to the same phylum as the polyps and jellyfish. The
actual polyps are not preserved, but their horny sheaths
have been carbonized and impressed upon the rocks.
a, Corncqraptus giacilis; b, Didymograptus pennatulus; c,
Climacograptus bicornis; d, Phyllograptus typus

(Rcdtaivn after Hall)

* Graptolite is from two Greek words, graptos, written, and lithos, stone.

FOSSILS

their horny sheaths have been carbonized and impressed upon
the rocks. Sometimes they are like miniature saw blades with
teeth on one or both sides; again they are leaf-like and may be
single or branched, the latter sometimes giving rise to dendritic
or tree-like colonies. The polyps were situated in the little
tooth-like notches. The animals may have been fixed to the sea
bottom as are their modern relatives, or attached to floating
material, or even provided with devices of their own to render
them buoyant. They were at the mercy of the waves or cur-
rents of the sea, since they had no recognizable powers of
locomotion. (See Figure 28.)

Zb.
Fig. 29 A GROUP OF BRACHIOPODS

1, Productus longispimts; 2a and 2b, Rhvnchonella quadriplicata; 3, Spirifcr striatus,
with part of the shell broken off to show the inner spiral supports

(After Grabau)

Trilobites were still existing in great variety, both of num-
bers and of kinds, and there was a host of shelled invertebrates
molluscs, and brachiopods or lamp shells (Fig. 29), as well
as corals.

Indubitable remains of armored, fish-like creatures have also
been found which show that the vertebrates had already de-
veloped, for these specialized fish are lateral offshoots from the
main line of vertebrate evolution.

The Silurian Period

The Silurian period gives us the first record of air-breathing
animals. Land plants had already been established, as plants
are necessarily the forerunners of the animals in any environ-
ment, for no animals have the power of constructive chemistry

PLANTS AND ANIMALS OF THE PAST 51

which would enable them to utilize products of the mineral
realm directly as food. They must, in the long run, avail them-
selves of the green or chlorophyll-bearing plants which do pos-
sess such ability. The first air-breathing animals of which we
have any actual evidence are the scorpions (Fig. 30), which, in
spite of their age, are much like those of today. As they were car-
nivorous and, therefore, did not eat plant food, their presence
implies also that of creatures which did and which in turn
formed their prey. For doubtless there was then, as now, an
ever-widening web of interdependence in organic life.

The fishes of the Silurian period are all in fresh water sedi-
ments. We have reason to believe that vertebrates had their
origin and initial evolution in running,
fresh water. This alone would give
the impetus apparently necessary to
produce the peculiar mode of progres-
sion by lateral wriggling which in
turn gave rise to segmental muscles and
an axial stiffening, the notochord. The
latter was later replaced in higher
groups by the vertebral column. Verte-
brates seemingly did not invade the
seas until late Devonian times; the
most plausible reason seems to have
been the menace of the molluscs, until
then the ruling denizens of the deep in
point of prowess.

The Devonian Period

Fig. 30 THE SCORPION,
PALAEOPHONUS NUNCIUS

Scorpions are the first air-
breathing animals of which there
11 i i \ c - 11 i i s an y actual evidence, and in

called the Age or rishes because they spite of their age are much like

those of today
(After Pirsson and SchucherO

The march of evolution progressed
markedly. Devonian time has been

were the dominant forms of life. Not
only are they numerous and well pre-
served, especially in the series of fresh water and estuarine
rocks known as the Old Red Sandstone,* but they had already

* Old Red Sandstone, a thick series of broken rocks, mostly sandstone, red
in color, belonging to the Devonian period and found in Great Britain and
northwestern Europe.

52 FOSSILS

differentiated into several distinct orders, such as the sharks, the
ancient armored fishes known as ostracoderms and arthrodires,
and the ganoid fishes and dipnoans. The last two groups
together with the sharks have left modern descendants, although
of ganoids and dipnoans there are but few survivors.

These modern relics aid us in the reconstruction of the
manner of life of those of Devonian times. All are fresh water
in habitat and have, though in varying degree, the power of
utilizing atmospheric oxygen in time of scarcity of available
oxygen in the water. The Devonian .period was a jime of
marked aridity of climate, r]pring which' the

periodically cease to flow with jresultant .stagnation of the ; fresh
water remnants which werejjsft, __ This would place a premium.
upn powers of endurance, and especially on air-breathing as
opposed to water-breathing^ For a while these fishes could sTill
carry on, especially if they could pass the worst of the droughts
in the condition of torpor known as estivation. But with prq->
gressivc aridity, extejiding.,5iiciL^ftexiQds^ over too great a J3c>;
portion of the c^jrture^ljf^ for

the normal activity <^ Jts^exjst^nce^he^ problem had to be rnet
In anotKer way by actual emergence and the assumption jojLa
terrestrial mode of life. This, aside from the ori^in^of life
itself and that of the Vertebrate type out of some unknown
worm-like ancestor, was perhaps^jblie mos^ni^mentgus occurrence
in all evolution. For it made possible the reptile, EIrdr~anct
mammal including man himself, and withouFlt tlie~"iTshcs~wgurd
be to this day the highesjt^expressiqn_of j^ertebrate progress.

The Devonian period saw not only the assumption of lung-
breathing on the part of certain fishes, but it also gave us in a
single archaic footprint (Fig. 9) the first tangible record of a
terrestrial backboned animal. Thus did our humble ancestor
leave behind him "footprints on the sands of time."

The conquest of the lands is first attained by the invertebrates
the scorpions, shellfish, worms, and thousand-legs. But these
are lowly folk and will never effectually dispute this new realm
with the vertebrates to come.

Devonian seas were replete with invertebrates corals,
brachiopods, trilobites, and molluscs, of much the same character
as were those of the Silurian period, and not until its close did the

PLANTS AND ANIMALS OF THE PAST

fishes invade the marine realm, as others of their descendants
invaded the terrestrial. It was a time prophetic of the roles the
backboned animals were yet to play.

The Carboniferous Period

The Carboniferous period which followed was also marked
by great events In organic advancement. In Lower Carbonif-
erous time the seas claim our interest, for the invertebrates are
developing remarkable types, especially among the sea-lilies or
crinoids (Fig. 31), the echinoids or sea-urchins T and the peculiar
screw-like colonial organisms (bryozoans) known as Archimedes,
from the philosopher of old (Kig. J^K ihere was also a great
revival of sharks, which, in spite of their antiquity, now become
Jominant marine forms.

The Upper Carboniferous period shows alternations of

and sea conditions, marine strata interspersed with those
Bearing beds of coal- the product ot the abundant vc^etation^
>f low-lying fresh-water swamps. These beds are our most

Courtesy of Dr. Carl D unbar

Fig. 31 -CKIiNOlDS or SEA-LILIES

Characteristic of the Lower Carboniferous period. The food is gathered by these pin-
nule-bearing arms from the sea-water and conveyed along a median groove to the mouth

FOSSILS

productive coal measures* and the debt of modern civilization
to them is immeasurable.

In the meantime, not only have the first land vertebrates, the

Fig. 32 A TANGLE OF FOSSIL HRYOZOANS

From the Helderbergian formation in Herkimer County, New York. These are

colonial polyps which secrete calcareous material around their bodies. They may

be attached to sea-weeds or rocks or may grow as free, fan-like expansions, or

independent masses of crowded calcareous tubes

Courtesy of Dr. Carl Diinbar

stegocephalians (Fig. 33), established themselves, but actual
reptiles have arisen, from which are to come, in turn, the "Rulers
of the Mesozoic era." The chief distinction between the stego-
cephalians, which were amphibians, and the reptiles lies in the
youthful stages the egg and adolescent; the former lay their
eggs in the water, and for a while their young are gill-breathers,
reminiscent of their piscine ancestors. It is only as adults that

* Measure, geologically, beds.

PLANTS AND ANIMALS OF THE PAST 55

they become truly lung-breathing terrestrial forms. With the rep-
tiles, on the other hand, the eggs are laid on land, and the young
are miniatures of their parents in all respects, gill-breathing being
lost forever. It is possible that aridity in late Carboniferous
time forced the abandonment of the amphibious life, though not
on the part of all, for the stegocephalians endured into Triassic

Fig. 33 A STEGOCEPTIALIAN, CACOPS ASPWEPIIORUS

One of the first land vertebrates

(Restoration after Abel)

time and the salamanders and frogs have existed until this day,
but on the part of those which by reason of environmental condi-
tions were destined to higher things. The amphibian stage in
evolution was merely en passant, for amphibians were never
dominant forms of life.

Yet another conquest was to occur during the Carboniferous
period, namely, that of the air, not by vertebrates this time but
by the invertebrates. For out of an humble trilobite ancestry,
through some obscure evolutionary line, the insects were to arise
and wing their way through the gloomy forests of the coal
swamps roaches, dragonflies, and archaic orders which, as such,
have ceased to be. Invertebrate air-mindedness preceded that
of the vertebrates by millions of years, for the latter did not
essay flight until the Triassic period.

The Permian Period

Rocks of the Permian period reveal climatic stress; gone are
diesteaming tropical forests, and aridity and glacial cold mark;
the period. Climatic influence on organic life is marked; insects
are few of record, and their enforced periods of hibernation seem

56 FOSSILS

to have given rise to the remarkable change from the gradual
metamorphosis of their ancestors to the abrupt one of the higher
orders, as seen in the beetles, butterflies, bees, flies the great re-
organization from grub to winged adult occurring during their
quiescent period instead of extending throughout much of their
active life, as in the roaches, grasshopper, dragonflies, and bugs.
Out of the Permian the higher orders emerge.

Whether or not the glacial cold of Permian time was con-
tributory to the establishment of warm blood in the ancestors of
birds and mammals remains to be proven, for the first recorded
mammals belong to Triassic time, and the first birds to Jurassic.
The inference, however, seems plausible that in some way aridity,
which makes for speed and higher metabolism, and cold which
places a premium on maintained internal heat and thus prolongs
the active period of an animal's life in inclement climates, are
responsible. Both aridity and glacial cold were characteristic of
Permian times.

With the appearance of insects, the invertebrate evolution is
complete, except for minor details of adaptation and structure.
And while the Permian period, which closes the great Paleozoic
era, saw also the extinction of important groups, notably the
trilobites, there has been no new invertebrate type established
since.

The vertebrates and higher flowering plants are to hold our
future interest.

THE MESOZOIC ERA

The Mesozoic era, which endured for 150 million years, has
been called the Age of Reptiles, for although the two higher
classes, the birds and mammals, both arose during the era, they
occupied subordinate roles, while all the niches in the economy
of nature, including the lands, seas, and air, were occupied by
the reptilian hordes. These ranged amazingly in size, from
minute nervous forms to the mightiest terrestrial brutes the
world has ever seen, and in their habits and adaptations, and
hence in their form and structure met every known condition of
life save that of the deep sea.

A conservative classification divides the reptiles into at least
eighteen orders, with suborders, families, genera, and species

PLANTS AND ANIMALS OF THE PAST 57

almost beyond reckoning. Of certain of these orders but few
examples have come to light, and these are from Africa and from
southwestern United States; yet other orders are known from
abundant specimens often of such degree of perfection that our
knowledge of their anatomy and inferred manner of life renders
them fully as familiar to the paleontologist as are many of the
existing animals of today.

The Triassic Period

Triassic time is ushered in by widespread aridity which seems
to have given the initial trend to the evolution of many reptilian
groups, notably the dinosaurs, for the first of these, both plant
and animal feeders, are bipedal in gait as though impelled to.
speed as a prime necessity of existence. They early fall into two
groups; probably they always were a divided race whose only
bond of relationship lay in their derivation from a common
ancestry.

The carnivorous dinosaurs arose as the earlier of the two
orders, having their recorded origin near the beginning of the
Triassic period, whereas the herbivorous order does not appear
till toward the close of the period. In both groups the main
evolutionary lines, while differing in certain diagnostic features
of skull, dentition, and pelvis, were, nevertheless, because of
their comparable gaits and sizes, closely parallel throughout their
entire course. There were aberrant* lines in both orders which,
because of weight of body, armor, or armament, forsook the bi-
pedal gait and descended once more to the quadrupedal pose of
their ancestors. Some of these, especially toward the close of
their career, attained a grotesqueness which made them fear-
some animals, as were others because of their size or their ter-
rible weapons teeth and claws or both.

Dinosaurs are first recorded from the Lower Triassic rocks
of Germany; but they soon spread to the uttermost parts of the
earth, from Europe to central Asia, southern and eastern Africa,
India, and Australia in the Old World, and from the Atlantic
coast to the Rockies and British Columbia or to Patagonia, in
the New. At first they dwelt in the drier areas, one of the most
famous of which was the Connecticut Valley in New England,

* Aberrant, deviating from the ordinary type.

FOSSILS

where their footprints are countless although their bones are
few. From the Jurassic period on, their known habitat seems
to have been low-lying coastal lands,
rich in heat and moisture, much of
which took the form of swamp and la-

Fig ZlBRONTOSAURUS EXCELSUS

This huge animal (about 70 feet long) was partly, if not wholly, aquatic, a wading

type with rather limited powers of swimming It must have fed on an abundance of

some sort of water plants

From a restoration by the autJior after the specimen in the Yale Peabody Museum

See frontispiece

goon or sluggish streams, and here the mightiest and weirdest
of them lived.

The Jurassic Period

One ofthejTiore notable dinosaurs was the Upper Jurassic
Vrontosaurus, a huge animal measuring about seventy_fggt_over_
jie curve of the backbone, bearing its weight. esjjmatcd__at^
jiirty-seven_tgns T on four great pillar-like limbs. It had a rather
;hort, compact body, but a long neck and tail and a relatively
;mall head armed with spoon-like teeth in the front of its jaws.
Brontosaurus is assumed to have been at least partly, if not

wholly, aquatic^T^^ 11 ^ tyP e w ^h rat hcr limited powers of
jwimmmg. It must have fed on an abundance of some sort of
tvater plants, although what they were has not yet been deter-
Timed. These were dislodged by means of the clawed front feet,
ind devoured without mastication. In a comparable form.
Barosaurus, therejwerc found within the ribs a quantity of highly
Dolished siliceous pebbles, which are supposed to have been con-

PLANTS AND ANIMALS OF THE PAST

tained in a muscular stomach and to have aided in digesting the
inert mass of food. Brontosaurus, although not the largest oT
dinosaurs, was, nevertheless, near the maximum size ever at-
tained by any animal except some of the largest of modern
whales, which because of their great girth and compact forrtv,
bulk vastly heavier at an equivalent length. Associated with
Brontosaurus in time and habitat was Allosaurus, a thirty-four
foot carnivore, with teeth like recurved daggers, and powerful
talons borne on both fore and hind feet. The latter probably
preyed on Brontosaurus, but whether it could slay one in the full-
ness of its strength, or whether the principal prey consisted of
lesser dinosaurs, with an occasional dead Brontosaurus which it
chanced to find, is not known. Allosaurus was certainly the most
efficient beast of prey of his day well weaponed, alert on his
two hind feet, in every way eminently fit.

Another associate was Stegosaurus (Fig. 35), an armored
dinosaur of lesser bulk, but of extreme grotesqueness, for the
back of this quadrupedal form bore a double row of huge, up-
standing plates, and the tip of the tail was armed with two or
more pairs of spines formed of heavy bone, which, together with

Fig. 35 SKELETON OF THE ARMORED DINOSAUR, STEGOSAURUS
UNGULATUS, IN THE YALE PEABODY MUSEUM

Though the bulk of this animal exceeded that of the largest elephant, its brain was
very small, not more than two and a half ounces in weight

FOSSILS

the plates, must have been sheathed with horn. The small head
bore a horny beak but rather feeble teeth, and the brain of this
creature, whose bulk exceeded that of the largest elephant, was
tiny not more than two and a half ounces in weight. The brain
was doubtless the seat of consciousness and of the interpretation
of such images of sight and sound that came to it, but of intelli-
gence it had hardly any at all. It was an excessively dull brute
whose reactions were largely physiological, but which, together
with its grotesque armor and armament, made for survival.
Stegosaurus did not, however, continue beyond the Jurassic or
early Cretaceous periods, although its relatives were able to carry
on for a time.

There were also unarmored, bipedal plant-feeders among
Jurassic types, such as Camptosaurus (Fig. 36). They were not
yet conspicuous, although their descendants were to be when the
giant amphibious dinosaurs had had their day.

The Cretaceous Period

In the Cretaceous the complexion of the dinosaurian societies
changed. Gone are Brontosaurus and its allies, their place
usurped by the types like Trachodon (Fig. 37) which not only
could wade freely but, as the webbed hands
and feet and the laterally compressed tail
attest, could swim as well as a
modern crocodile. The larg-
est of these was about
thirty-five feet, half
the length of Bronto-

Figure 36

CAMPTOSAURUS,
AN UNARMORED,
BIPEDAL, PLANT-
FEEDING DINOSAUR

It had an average length of about ten feet, and was found in the Juiassic period

of North America

From a restoration by the author, based upon the skeleton in the American Museum

of Natural History

PLANTS AND ANIMALS OF THE PAST

saurus, and the weight proportionately much less. The skin,
which is sometimes preserved, shows no trace of armor but
was covered with small scales arranged in definite patterns.
Its mouth armament, however, was remarkable. A broad,
toothless beak, not unlike that of a duck in shape, covered
either with a leathery or horny skin, formed the front or food-
getting portion of the mouth. The rear half of each jaw bore
within itself a wonderful battery of teeth formed in a number
of vertical rows, which moved outward to compensate for wear,
new teeth developing in the depths of the jaws. Thus each
half of each jaw possessed some twenty-seven to thirty vertical
rows of ten to fourteen teeth, making upward of more than
a thousand, all told. And these are what the specimen now pos-
sesses and does not account for those which had been worn away
by use.

In Europe, Iguanodon (Fig. 38), an earlier genus (Lower
Cretaceous period), was comparable in appearance to Tracho-
don but without the extreme of specialization, except for curious,
spike-like thumbs, apparently its only weapons. Certain American
trachodonts, notably from Alberta, developed strange crest-like
modifications of their skull, the meaning of which is not clear.

Fig. 37 THE DUCK-HILL DINOSAUR, TRACHOUON

So called because of the broad, toothless beak which formed the front or food-eettinir

portion of the mouth. The posterior part of the mouth bore a wonderful batterv of

teeth more than 1000 all told

From a photograph of a skeleton in the Yale Peabody Museum

FOSSILS

They have their analogy in the crests of certain birds and the
various "ornamental" excrescences of modern lizards, the use of
which, unless it be a sex distinction, is equally obscure. Stego-
saurus had also passed away; but its group, the armored dino-
saurs, was represented by yet weirder forms, like Palaeoscincus,
or Ankylosaurns, heavily armored, spined and tubercled, with de-
pressed, somewhat triangular, head, strongly beaked, but with
feeble teeth or none at all. Their very immobility and heavy
armor made these dinosaurs practically immune to successful at-
tack.

Not all, however, were weaponless, for some had a great
club-like expansion on the end of the tail, a veritable bone-crush-
ing battle-mace, which, while clumsy, may have proved highly
effective as a defensive organ when a carnivore had the hardi-
hood to attack them.

Another group of dinosaurs are new to the scene, for we
know of no Jurassic or early Cretaceous form which could pos-

Fi g . 38 ANOTHER BEAKED DINOSAUR, IGUANODON

No fewer than seventeen remarkably preserved skeletons were found in a coal mine at

Bernissart, in Belgium, and are mounted in the liiussels Museum of Natural History.

Iguanodon was about timty-four feet in length, and bore upon the hand, by way of

a weapon, a peculiar spike-like thumb

(.Adapted from Hcilmann)

sibly have sired them. These are the Ceratopsia, or horned
dinosaurs, known, until recently, exclusively from the lands
bordering on the eastern uplift of the Rocky Mountain region.

PLANTS AND ANIMALS OF THE PAST 63

Ancestors which had all their characteristics, except the horns,
have recently come to light in Protoceratops of far Mongolia.
A typical American form is Triceratops (Fig. 39), from the up-
permost Cretaceous beds, who was an associate in the rocks, if not
in life, with Trachodon and the armored forms of which we have
spoken.

In Triceratops the head was huge, being upward of one-third

Fig. MTRTCERATOPS ELATUS, ONE OF THE GREAT HORNED DINOSAURS
WHICH LIVED IN THE CRETACEOUS PERIOD

It was about twenty-five feet in length, with a skull over ei<;ht feet loncj the largest
skull of a land animal known to science

From a restoration by the author, based upon the skcJcfon in the American Museum

of Natural History

the overall length of the animal. It was borne on a bulky body
with bowed forelegs and somewhat straighter hind ones and
a rather short tail. The skull had a very small brain case, with
a secondary over roofing of bone which was extended backward
into an expanded crest or frill, which, during life, was closely
invested with horny skin. This crest not only afforded leverage
for wielding the head but also a protection for the nerves and
blood vessels of the neck. A rather long face and deep muzzle,
armed with a compressed turtle-like beak, completed the head,
except for the horns. These were borne on the nose and above
the eyes and vary greatly in their development in the different
genera and species.

Monoclonius (Fig. 40), an earlier genus, possessed but one

64 FOSSILS

horn, the nasal, but Diceratops, a contemporary of Triceratops,
had two above the eyes, that over the nose having disap-
peared.

In most of the later dinosaur types the crest was a complete
buckler of bone; in the earlier ones it was perforated by aper-
tures varying in size and shape, and in one form, Styracosaurus,
the outer edge of the crest bore huge horn-like spines. All were
grotesque animals; but while reptiles, with all that that implies,
they were very rhinoceros-like in general appearance. In si/e the
largest Triceratops must have attained a length of twenty-five
or more feet, with a skull over eight feet long the largest skull
of a land animal known to science.

All of these, Trachodon, Palaeoscincus, and Triceratops,
were herbivorous, their arch enemy of the carnivorous phylum
being Tyrannosaurus (Fig. 41), the most appalling devourer of

flesh that ever stalked the earth. A
ponderous body borne aloft on two
massive legs armed with curved
claws, and balanced by a heavy tail,
Tyrannosaurus reared its huge head,
with its cruel teeth, eighteen feet in
the air. Its arms and hands were so

Fig 40-TITF. HEAD OF VC1 7 Smdl tHat ^ Can Ot i^'" 6

MONOCI.ONWS w hy it had them at all, except pos-

ta ?hT"ow!a e nd"'orwh r a, W arp r ^n d t sibly for pairing, but they show the

&A e Ja k . y M^h^'and tendency of evolution of the group,

adapfedVfo? bot" Xnive "mi for while the other members keep

defensive operations . , . , i 11 ,1 r i i_

., . .. , .. .. pace with body bulk, the fore limbs

From a restoration by the author ~ J '

become proportionately smaller and

smaller until the marked disparity in Tyrannosaurus is reached.
The latter, with its forty-five feet of length, was not only the
most powerful but actually the largest dinosaur of its time
and shows the final culmination of the race before ultimate
extinction.

But not all of the carnivores of that time were large, for
there was a race of smaller and lighter beasts of prey, whose
evolution has been traced from the Connecticut Valley forms,
a foot or so in length, through Compsognathus of Solnhofen
(Fig. 18), two and a half feet, to Struthiomimiis, the ostrich-

PLANTS AND ANIMALS OF THE PAST 65

mimic (Fig. 42), of the late
Cretaceous period. This last, with
its compact feet and toothless
beak, resembled an os-
trich in appearance, ex-
cept for a long tail,

Fig. 11TYR4NNOSAURUS, THE LARGEST AND MOST POWERFUL
CARNIVOROUS DINOSAUR OF ITS TIME

It was forty-five feet long and stood eighteen feet high, the entire weight of the body

being supported on the massive hind limbs. The head was four feet in length, and the

powerful jaws bore teeth from three to six inches long

From a restoration by the author

and doubtless was similar in its habits of life. It was by
far the speediest among the dinosaurian horde.

Other Great Reptiles

Of marine reptiles there were several kinds, for no fewer
than six reptilian orders took to the high seas for their livelihood
during Mesozoic times. There were the turtles, crocodiles, mosa-
saurs or marine serpent-like lizards,
allied to the monitors of today, and
plesiosaurs with bulky body, four pad-
dle-like limbs, and long neck bearing
a quick, darting head which made up
in its speed what the entire organism
lacked. But perhaps the finest of all
in its perfection of adaptation to ma-
rine life was the "fish lizard," Ichthyo-
saur (Fig. 43), stream-lined like a
modern porpoise, with a long mouth
armed with prehensile teeth, a power-
ful propelling tail with a vertical fin, (.Modified from

Figure 42

THE OSTRICH-MIMIC,
STRUTHIOMIMUS ALTUS

By far the speediest among the
dinosaurian horde

66 FOSSILS

a dorsal fin, reduced hind limbs, and the fore limbs transformed
into paddles. Not only were the ichthyosaurs dolphin-like in
appearance, except that their tail fin was vertical instead of being
horizontal, but their manner of life was the same, even to the
feeding habits, for their coprolites show that their food con-
sisted of fish and cephalopods upon which modern dolphins prey.
They are totally unrelated to the whales, even though, like them,
they brought forth their young alive; but they represent a mar-
velous instance of convergent evolution in which Nature has
repeated herself, although with creatures of a totally unlike sort.
The ^ : minded reptiles werejthe pterosaur^ or pterodactyls
whose pinions diffefcB fr_omThose o^birds and resembled those
of bats in that the supporting surface consisted of a fold of the

Fig. 43 THE MARINE REPTILE, ICHTHYOSAUR (Stenoptcrygnts)

in-likc both in appearance and in habits. Tt is an example of perfect adaj
from a terrestrial to an aquatic environment

Fiom a restoration by the author, based upon the skeleton by l r on Hucnc

skin borne by the arm, an elongated single finger, and a hind
limb. In the UpKCj^^i^sic^jg^rigd^ pterosaurs appeared
abruptly out of an unknown^ncestry, enduring until the Upper
Cretaceous time but dying out apparently before its closeT
Splendid examjgles^ sudi^^^

from the Upper Jurassic bed at Solnhofen, but the culmination
was Pteranodon (Fig. 45), a toothless form with fish-eating
habits analogous to the existing pelicans. Pteranodon had a wing
spread of upward of twenty-five feet the greatest flying crea-
ture in Nature's realm. It is found in the Upper Cretaceous
Niobrara deposits of Kansas.

These were but a few representative groups of reptiles; there
were others, less spectacular, which made up the great reptilian
dynasty of the Mesozoic.

PLANTS AND ANIMALS OF THE PAST 67

Mesozoic Birds

Mention has been made of representatives of the two higher
classes, birds and mammals, which also existed, but filled minor

l-i. 44-T11K GUKAT HAJNG KKl'TJLK, KlUMt'llUKliy
Even the impression of the delicate wing membranes is beautifully preserved

From a photograph of the Yale Peabody ^Museum specimen from the Jurassic deposits

at Solnhofen

roles in the medieval drama. Of the birds, the first was Archae-
opteryx of Solnhofen (Fig. 46) , so reptile-like in many ways that,

ig. 45- SKELETON OF NATURE'S GREATEST FLYING CREATURE, PTERANODON

This specimen in the Yale Peabody Museum had a wing spread of eighteen feet It
came from the Cretaceous chalk strata of western Kansas

Fig. 46 RESTORATION OF ARCHAEOPTERYX, THE FIRST TRUE BIRD
KNOWN TO GEOLOGICAL HISTORY

Though undoubtedly a bird, it had many reptilian characters, among which were the
presence of teeth in both jaws, the free, clawed fingers of the hand, the poorly developed
breastbone, and especially the long vertebrated tail, which, however, was furnished
with feathers on both sides. In all later birds, the tail is short, and the feathers

disposed fan-wise

(From Heilmann)

PLANTS AND ANIMALS OF THE PAST

were it not for the preserved feathers, one would hardly be justi-
fied in assuming it to be a bird at all. Toothed, with feeble powers
of flight, and a long lizard-like tail with a row of feathers on either
side, these generalized forms were very different from the
feathered songsters we know. Yet, had they not been dis-
covered, they are about what one would predict for transitional
forms from reptiles to true birds.

These Jurassic birds were succeeded in the Cretaceous period
by Ichthyornis, not unlike the terns of today except that it also
possessed teeth, and Hesperornis, a splendid creature nearly six
feet in length, resembling a large flightless diver (Fig. 47).
Hesperornis was also toothed, but its wings were reduced to a
pair of long slender upper arm bones. Even the breast bone
had lost the keel, to which the great muscles of flight are
normally attached, in a manner comparable to that of the modern
flightless birds, like the ostrich. But there the ostrich-like char-
acter ends, for Hesperornis was a marine bird, of habits analo-
gous to the existing loons. Our fossil record of birds is always
meager, for they rarely are entombed as are other forms of life.

Fig. 47 THE SKELETON OF ONE OF THE TOOTHED BIRDS, HESPERORNIS

This specimen in the Yale Peabody Museum came from the Niobrara formation of
Kansas. It was about four and a half feet long, had lost the power of flight, but
had developed powerful hind limbs well adapted for swimming

70 FOSSILS

We are fortunate in that the three or four Mesozoic birds which
we have are in so high a degree of completeness. They are,
however, all marine and are all toothed. If we knew the true
land birds of the Mesozoic, of graminivorous habits, it is highly
probably that we might find toothless ones in every way com-
parable to those of today, though without their range of special-
ization in numbers and kinds.

The Warm-blooded Mammals

The warm-blooded mammals are the familiar quadrupeds or
beasts of today, and though neither title properly applies to
mankind, man nevertheless belongs to the class. Their advent
in geological time is therefore of double interest to us, both
on account of our many contacts with the "beasts of the field"
and also because of our lineage. Mammals arose out of a group
of reptiles known as cynodonts (i.e., dog-toothed), primitive
in many respects, but differing particularly in their dentition, for
while with reptiles in general teeth may vary in size in certain
parts of the mouth, here they are clearly differentiated into in-
cisors, canines, and cheek teeth, as in a mammal. Cynodonts are
found in continental strata of Triassic age in various parts of
the world, but especially in what is known as the Karoo forma-
tion of South Africa, which contains also undoubted mammals.

All of the known mammals of the Mesozoic era have the
common property of small size, averaging up to that of a rat,
although certain skulls from central Mongolia indicate some-
what larger creatures. None is large, however, in the sense that
the reptiles were. The remains, though locally fairly abundant,
are nevertheless among the rarest of fossils of Mesozoic time,
and in no known instance has anything approximating a complete
skeleton been found. On the contrary, the fossils are extremely
fragmentary, consisting principally of isolated teeth, many jaws,
both upper and lower, rare portions of skulls, only three or four
of which are fairly perfect, and a few skeletal elements, which
never, so far as known, can be associated with their appropriate
jaws and teeth. Thus it is obvious that we can have no clear
vision of a complete animal, such restorations as have been at-
tempted having a large degree of conjecture and inference from
related forms of the Cenozoic era.

PLANTS AND ANIMALS OF THE PAST 71

We know, however, that the Mesozoic mammals differed
markedly in tooth structure and hence in feeding habits, that
some were vegetarians and others devourers of animal life, al-
though from their lack of prowess, the prey of the latter must
have been proportionally feeble. The insectivores of today feed
upon insects, worms, grubs, small reptiles and birds; so must it
have been with the carnivorous mammals of the Mesozoic era.
Two of the most productive localities in America are the Como
Bluff, of Jurassic age, where they were associated with the great
dinosaurs, Brontosaurus, Allosaurus, and others, and the Creta-
ceous beds of Niobrara County, which produced Triceratops,
Trachodon, and Tyrannosaurus. These localities are both in
Wyoming. In every instance mammals are associated with
dinosaurs, which implies the same geological and geographical
distribution, but not necessarily the same environment, for Dr.
William Dilter Matthew (1871-1930), of the University of
California, thought that the Mesozoic mammals were largely,
if not exclusively, tree-inhabiting, whereas the dinosaurs were
terrestrial or partially aquatic.

It is possible that future research may reveal as yet unknown
areas in which, on account of different conditions of environment,
mammals may be found differing markedly in size and in other
characters from those we now know. In the light of our present
knowledge, the most amazing thing about them is their apparent
stagnation, for, aside from tooth detail, they show little evolu-
tionary advancement from their first appearance in Upper Trias-
sic rocks until the close of the Cretaceous, over 100 million
years ! This is the more surprising when one remembers that
out of some Mesozoic mammals, known or unknown, are to arise
all of the higher orders. The potentiality to evolution must
have been there, and, if so, it was held most effectively in check,
presumably by the ruling dynasty, the reptiles.

Extinction of the Great Reptiles

Reptilian extinctions which occurred with such apparent sud-
denness at the close of the Cretaceous, leaving but few survivors
out of the many orders of highly efficient creatures, were of
paramount importance for the mammals. Occasionally Nature
seems to wipe the slate clean of once dominant forms and start

72 FOSSILS

afresh with creatures whose role had been one of subordination
and thus people the world anew. So it was at the end of the
Mesozoic era. How this was brought about is a mystery, though
a number of explanations have been offered. Were we thinking
of dinosaurs alone the problem would be simpler, but the great
extinction swept the reptiles from the high seas and from the
air, as well as from the lands.

The close of every era, Paleozoic, Mesozoic, and Cenozoic,
has been marked by great geologic change; orogenic, or moun-
tain-making movements, are everywhere manifest, and, what-
ever their influence on climate, they are critical periods for
animal life, for always when these "revolutions" are past old
familiar types are among the missing, evolution is accelerated,
and new groups arise.

Not always is plant evolution synchronous with that of
animals. In fact it usually precedes the latter. * Thus, while
plants became fully modernized during the Cretaceous period,
the dinosaurs still held sway and adapted themselves to the
changed appearance of the plant world without marked change
on their own part. This but adds to the difficulty of the problem.

THE CENOZOIC ERA

With the passing of the reptilian dynasties the mammals
come into their own and in their turn become what we have
called dominant forms of life. It is interesting to note that each
wave of dominance arises out of what were humbler and less
specialized forms. Dominant never produces dominant of the
same lineage. It is a replacement, not a succession in the sense
of related beings, as the succession of the kings of the house of
Stuart or of Hapsburg.

The Archaic Mammals

Two successive waves of mammalian evolution occur in the
Cenozoic era, the first of which immediately followed the extinc-
tion of the great reptiles. This concerns the so-called "archaic
mammals" which, while showing remarkable adaptations in
many respects, are also characterized by certain constitutional
inhibitions which apparently they were unable to overcome and
which were so serious as to doom them from the start.

PLANTS AND ANIMALS OF THE PAST 73

There are three essentials of mammalian evolution, the first
two of which are the feet and the teeth, which are perhaps the
parts of the animal most closely in contact with the environment
and which were the concern of the reptiles as well. In the
Cenozoic era to these two was added the brain, and for the first
time a premium was placed upon the psychological aspect of an
animal's fitness for survival. This was largely unessential in the
reptilian evolution. The archaic mammals possessed all three;
but in no instance within the group were they capable of the
development and specialized adjustment which their modernized
successors displayed, for out of the latter, with few exceptions,
the existing mammals have come. Their feet were always primi-
tive five-toed, clawed, or hoofed but never capable of such
specialization as occurs in a horse or cat. The teeth, while dif-
ferentiated and in rare instances specialized as to tusks, never
showed, especially in the molars, a perfection of adaptation to
a particular diet, such as grass or flesh. Finally, the brain is
actually small in proportion to the bulk of the animal, although
far better in this respect than in the reptiles. Casts of the in-
terior of the brain-case, either natural or artificial, give an ex-
cellent replica of the vanished organ. While the parts which
have to do with sense perception and muscular co-ordination are
fairly well developed, the cerebral hemispheres, which are the
seat of intelligence, are relatively very small and their outer
surface is smooth, showing a very limited cortex, the so-called
u gray matter" of popular usage. These were altogether stupid
beasts, well enough perhaps when all were of the same degree
of mentality, but unable to cope with the invading army of
intelligent, modernized creatures which shortly overwhelmed
them.

Several orders of mammals are classed as archaic. They
make their appearance in the opening period of the Cenozoic,
the Paleocene, and all but one or two genera have disappeared
by Oligocene time, unless certain groups, such as the sloths and
armadillos and the pouched marsupials, are living survivors.
The most notable among the archaic mammals were the
creodonts, primitive flesh-eating animals of greater prowess than
the Mesozoic carnivores. Some of these were weasel-like, some
resembled the dogs, others were hyena- or bear-like, and doubt-

FOSSILS

less of comparable habits in each instance. A very dog-like
form is Dromocyon (Fig. 48), from the Bridger Eocene strata
of Wyoming; the skull of a gigantic type, Andrewsarcus, was
discovered in Mongolia by the American Museum expedition of
1923. Dromocyon has a large head in spite of the small brain-
case, size being necessary to provide attachment for the large
muscles which the inefficient teeth required for anything like
effective use.

In addition to the creodonts, there were two orders of
herbivores, the condylarths and the amblypods. Of these the
first were, on the whole, lighter of build and more or less adapted
for speed; in fact, they paralleled the creodonts rather closely,
except for the contrast of diet which their teeth indicate. One

Fig. 48 DROMOCYON I'ORAX, A DOG-LIKE CREODONT FROM THE MIDDLE
EOCENE STRATA OF WYOMING

In spite of its comparatively large head, this archaic mammal possessed an extremely

small brain-case

From a restoration by the author, based upon the skeleton in the Yale Peabody Museum

notable specimen was Phenacodus primaevus, an animal about the
size of a sheep (Fig. 49). This was discovered years ago in the
Bridger beds of Wyoming by the noted American paleontologist,
Edward Drinker Cope ( 1 840-1 897 ) , and is now in the American
Museum of Natural History. When first found, Dr. Cope
hailed it as the five-toed ancestor of the horse, which has been
ardently sought for, thus far without success. The large size
and inadaptive characteristics, together with the fact that it is
contemporaneous with Eohippus, the four-toed horse, debars it
absolutely as the forerunner of a proud lineage.

The amblypods were, as a rule, much larger than the con-

PLANTS AND ANIMALS OF THE PAST 75

dylarths, heavy-bodied and ungainly, with stumpy or splayed five-
toed feet. Of these, Coryphodon (Fig. 50), again from the

Fig. 49 t J HENACODUS PRIMAEVUS, ONE OF THE PRIMITIVE CONDYLARTHS

It survived until the end of lower Eocene time and was a contemporary of Eohippus

From a restoration by the author, based upon the skeleton in the American Museum

of Natural Hut or y

Bridger, was about the size of a small rhinoceros, with flaring
tusks almost like those of a wild boar, and an absurdly small
brain. The character of the feet indicate a swamp-dwelling
creature.

The culminating amblypod, by far the most grotesque of

Fig. 50 CORYPHODON HAMATUS, AN AMP.LYPOD FROM THE BRIDGER
BEDS OF WYOMING

It was about the size of a small rhinoceros, with flaring tusks almost like those

of a wild boar

From a restoration by the author

FOSSILS

all the archaic mammals, was Dinoceras (Fig. 51). Large, al-
most elephantine of body and limbs, standing about six feet at the
withers, this strange brute had a most unusual head. It was
rather long, with three pairs of horn-like eminences on the skull,
a pair on the nose, one above the eye, and again a pair at the
hinder end. These were doubtless sheathed with horn and may
have served in a measure as weapons. Dinoceras was further
provided with a pair of dagger-like tusks, the canine teeth of the

Fig. 5^ DINOCERAS 1NGENS, THE MOST GROTESQUE OF THE
ARCHAIC MAMMALS

It was almost elephantine in body and limb, standing six feet at the withers. The
armament of Dinoccras may have served a useful purpose, but it is more likely an
indication of racial senility

F)om a restoration by the author

upper jaw, which pointed downward and were protected, when
the mouth was closed, by a large bony flange on the lower jaw.
The tusks and horns vary with the species and sometimes within
a species, possibly as a sex character, the more heavily armed
individuals being apparently the males.

Dinoceras first appears in the Bridger, Middle Eocene,
beds and ranges up into the Uinta formation, the closing member
of Eocene time, during which a marked evolution of the skull,
horns, and tusks is seen. The molar teeth, however, are prac-
tically unaltered in form and size, in spite of the changes in the
skull and armament. They are a curious illustration of a veneer
of specialization in a primitive beast. The brain, although larger

PLANTS AND ANIMALS OF THE PAST 77

than that of Coryphodon, is still very small compared with the
elephantine bulk of its owner. These archaic mammals evidently
had their origin, as well as their subsequent evolution, largely
in the western part of North America, being found chiefly in
Wyoming.

The Modernized Mammals

In the meantime, however, there begins the invasion of
middle North America by the advanced scouts of a conquering
army, the modernized mammals, which, as we have mentioned,
include the actual forebears of the existing beasts and of men.
These forms had no such constitutional limitations as had the
archaic, for the three essentials, feet, teeth, and brain, are po-
tentially capable of the highest specialization. But not all of
the modernized mammals developed the three equally well;
the horses "elected" development in each, the elephants in two,
the teeth and brain, retaining primitive feet, whereas human
evolution has stressed but one, the brain, the teeth being ex-
tremely primitive, the hands as well, while the feet show a little
specialization, but not much as compared with many other
mammals.

The rather sudden and simultaneous appearance of the
modernized mammals in both the Old World and the New,
points to an origin and initial evolution in some region contiguous
to both. If one looks at a polar projection of our earth, in the
northern hemisphere, he will see the great continental masses
converging toward the pole and radiating outward toward the
south. The circumpolar area, therefore, forms with a few
breaks a common land from which lines of migration run down
the continental axes, the Americas, Europe and Africa, and Asia.
While there is no direct evidence, such as the finding of circum-
polar fossils, that region is the only one from which these crea-
tures could have come in order to arrive simultaneously, as they
did, in the several remote lands.

The climate of this northern land was mild, but apparently
variable, which is always a higher stimulus to progress than
would be the warm, moist, uniform climate of the Eocene period
in Wyoming. This may have made possible the evolution of
the higher types in the north rather than in Wyoming. The

78 FOSSILS

southward migration seems to have been caused in part by
climatic pulsations, tending toward greater severity, for the
animals come not all at once but in a series of invading waves
and in part by pressure of numbers, which always impels migra-
tion wherever possible. At once the invaders entered into com-
petition with the archaic mammals, the fate of which is doubtful
except that they disappeared from their old territory forever.
Some were driven southward where they formed some part of
the curious South American and African faunae; others, unable
to endure the competition, finally became utterly extinct. Yet
others, and these were very few, may have given rise to some
at least of the existing animals, possibly the true Carnivora. The
modernized mammals now possess the land. We have space
for the consideration of very few, but the three groups mentioned
above, horses, elephants, and humanity, should be described the
first because of the completeness of our record of the stages which
link the earliest, Eohtppus, with the horses of our time; the
second not quite so complete, but of great interest; and the third,
though the least perfect of all, because of the personal appeal.

CHAPTER VII

FOSSIL HORSES

YEARS of exploration in Europe and North America have
given our museums a wonderful array of fossil horses.
When a few had been found, the line of evolution was thought
to be a single straightforward thing; but with the abundance
of material the problem becomes complex and we find several
parallel and divergent descent lines, some of which died out from
time to time until one genus alone survives, although in several
markedly different species.

THE DIFFERENCES BETWEEN THE HORSE AND His
UNKNOWN ANCESTOR

The recorded evolutionary changes are, briefly : ( 1 ) , increase
from three to sixteen hands in shoulder height; (2), increase of
about 200 times in bulk; (3), a change in the dentition from
short-crowned grinders bearing a half-dozen or so isolated cusps
to more complex grinders and enlarged cropping teeth; (4), an
increase in length and in simplicity of the feet as an adaptation
for speed.

In the evolution of the teeth, the isolated cusps fused into
crests, the valleys between the crests becoming flooded with
cement, and the teeth lengthened, becoming prismatic with elabo-
rate patterns caused by the infolding of the outside enamel. The
premolars, at first simpler than the molars, became successively
molar-like, beginning with the hindermost, until instead of four
premolars and three molars, there were six grinders in each half
jaw, all essentially the same in appearance, while the first pre-
molar had become the vestigial "wolf tooth. " In the modern
horse, the jaws have elongated and deepened to give room for
the increase in size of the teeth and the separation of the crop-
ping teeth from the grinders by the gap or diastema.

The unknown hypothetical ancestor was doubtless five-toed

80 FOSSILS

both in front and behind, the bones of the hand being sug-
gestive of our own. Gradually the hands and feet were raised
higher on their digits, of which the third or middle one was des-
tined to bear the most weight. The lateral toes diminished pro-
portionately, starting with the first,, then the fifth, and finally the
second and fourth together, so that there are four-toed horses
known to science, then three-toed, and finally one-toed, but never
two-toed. In the final stage, vestiges of digits two and four
remain as splints on either side of the canon bone, just as in
earlier stages vestiges of the first and fifth remained for a time
after the real toes had disappeared.

THE TEN STAGES IN THE EVOLUTION OF THE HORSE

In the actual fossil record there are ten stages recognized
as characteristic of the successive geological horizons not that
this implies abrupt changes but quite the contrary, for it is obvi-
ous that to have a complete series there should be a specimen of
each generation, a manifest impossibility. The geological hori-
zons, as we have seen, are separated by time intervals during
which a break in the continuity of sedimentation occurs. The
specimens of these lost intervals, which may represent many
generations, are also lost, hence the apparently abrupt change
when the fossils reappear. The several stages are as follows:

1. Eohippus, the first known stage in the evolution of the
horses, is found in our West in rocks of Lower Eocene age and
their equivalent in the Old World. The European form, Hyraco-
therhim, of the London Clay is somewhat more primitive in
tooth structure and, therefore, possibly older. Eohippus had
four toes in front and three behind, for at first the evolution of
the foot is more rapid than the hand, due in part to its having
a somewhat greater share in the propulsion of the animal. The
height at the shoulder was about eleven inches, the back was
arched, and the head and neck were rather short, but Eohippus
had moderately long limbs, the proportions being not unlike those
of the racing hound known as the whippet. It must, therefore,
have been an animal with a fair turn of speed for its size. The
teeth were short-crowned, with the primitive cusps beginning
to fuse into crests. This genus had a remarkable geographic
range, for, after evolving in some northern area, it migrated

LIVING OLD WORLD EQUUS
(Horses, Asses, Zebras)

Unknown Five-toed Ancestor

Fig. 52 PTIYLOGENY OF HORSES

a, Eohippus; b, Orohippus; c, Mesohippus; d, Merychippus; e, Pliohippus; f, Equus;
g, Hypohippus; h, Hipparion; i, Hippidium

Horses a-f represent the main line of descent; jr, h, and i, collateral lines which

have become extinct

(After Lull)

82 FOSSILS

southward as far as New Mexico in the New World and
Europe in the Old.

2. During Eocene time the horses increased in size and
suffered further diminution of the fourth digit of the hand,
but all are four-toed horses nevertheless, although other generic
names are applied to them, Orohippus of the Middle and
Epihippus in the Upper Eocene.

Although in America the horses form a continuous series
from Eohippus to Equus, in the Old World the line is broken
from time to time. It is assumed, therefore, that the real
theater of their evolution, after the initial appearance, was
North America, from which they migrated, as opportunity arose,
via one or more land bridges over which traffic was not, however,
continuous. What caused the repeated extinctions in the Old
World after each invasion is not clear, for at the end the condi-
tions were reversed and final extinction occurred in the New
World and survival in the Old.

3. Mesohippus was the first three-toed stage, for now the
hand, except for a vestige of the fourth digit, had overtaken
the foot in its evolution, and henceforth their development is
comparable. Mesohippus also varied in size but averaged
eighteen or more inches in height, was slender-limbed and better
adapted for speed.

4. Miohippus, the fourth stage, differs but little from its pred-
ecessor except in size, which is increased to twenty-four inches.
Mesohippus was Lower and Middle Oligocene, whereas Mio-
hippus comes from the upper beds. A derivative of Miohippus
known as Anchitherium, made its appearance in Europe in the
Miocene, the result of the second migration.

The climate of the Eocene and the Oligocene periods was
warm and moist, with an abundance of succulent vegetation for
these small browsing horses. But in the latter period there is
already an expansion of grasslands, prophetic of the widespread
prairie conditions which the growing aridity of the Miocene
was to foster.

Miocene horses are several, not all of which were in the
direct line of descent; all were three-toed, however, although
varying in the development and utility of their lateral toes. In
the main line were :

FOSSIL HORSES 83

5. Parahippus, yet a browsing horse with short-crowned
teeth.

6. Merychippus, forty inches tall, whose milk teeth were
short-crowned but whose permanent grinders were prismatic with
infolded enamel, an adaptation to harsher herbage.

7. Protohippus, whose milk teeth as well as the permanent
set were long-crowned.

Three or more side lines occur: Anchitherhim, to which refer-
ence has already been made; Hypohippus, pony-like in size, with
well developed side toes, thus adapting the creature for yielding
ground, and short-crowned teeth set in shallow jaws. Hypo-
hippus is sometimes described as a forest horse, but the feet
are analogous to those of the reindeer which is adapted to the
mossy tundras. At all events Hypohippus was not a prairie
horse, and by the beginning of the Pliocene it became extinct
as a race.

A third collateral line was Hipparion, again a migrant to
the Old World where it survived until near the close of the Plio-
cene. Still three-toed, with lateral digits that occasionally touched
the ground when the going was soft, Hipparion had the most
complicated teeth thus far recorded. It stood about forty inches
at the shoulder, a speedy creature of somewhat deer-like pro-
portions. Hipparion also died without further issue, leaving the
main stream of equine blood to

8. Pliohippus of the Pliocene, the first one-toed horse, al-
though some of the species of this genus may have retained
small, practically useless, side toes, like the "dew claws" of
cattle. By Upper Pliocene time, Pliohippus had merged into

9. Plesippus, whose lateral toes had entirely disappeared
and whose stature almost equaled that of Equus, which still
lives in the modern horse.

10. Equus is Pleistocene in time and had spread to South
America as well as to the eastern hemisphere. Then came the
final extinction of the horse in the Americas, of which we cannot
yet clearly define the cause, for, whatever it was, it did not affect
either the Asiatic or African horses, although as wild animals
they have also disappeared from Europe.

The Pleistocene period was characterized by the mantling
of the northern continents with vast sheets of ice, which flowed

84 FOSSILS

and ebbed and flowed again, there being in America four, pos-
sibly five, periods of advance separated by much longer periods
of mild and even salubrious climates. In the southern hemisphere
the ice was more local, existing not as continental ice sheets such
as still mantle Greenland and Antarctica, but as alpine glaciers
in the vicinity of which domestic horses live and thrive.

Some devastating insect-carried disease, such as the sleeping
sickness of Africa, or the surra disease of India, has been sug-
gested, brought in by some invading mammals which could carry
the parasite and yet, themselves, be immune to its effects. An
insect, such as the tsetse fly of Africa, is the intermediary be-
tween one mammal and another. That the Americas are now
a splendid horse environment is attested by the hordes of wild,
or secondarily wild, horses, the mustangs, which have overrun
both continents from a very small beginning the few horses
brought over by the Spanish conquerers and left behind when
they had no further use for them.

This we know, that the Glacial period was a very critical
time for animal life, although in just what way the influence was
felt is still obscure. At all events, many splendid forms fell
before its onslaughts, including the native American horses.
In Asia and Africa, on the other hand, the indigenous horses
still survive, the Prjevalsky horse and the kiang of Mongolia,
the Nubian and Somali asses of northern Africa, the first to be
domesticated, and finally the African zebras. Were it not for
the final migration of Equus to the Old World, man's most
faithful companion, with the exception of the dog, and certainly
the companion to which his civilization owes the most, would
never have been available, and as a consequence his march of
culture and commerce would have been retarded immeasurably.
It is said that the mysterious Maya civilization of Central Amer-
ica is the only one which has ever arisen among people who pos-
sessed neither metal tools nor the horse.

CHAPTER VIII

FOSSIL ELEPHANTS AND MASTODONS

ELEPHANTS and mastodons are included in the Proboscidea,
a group of hoofed animals characterized briefly by gigantic
size and the possession of the trunk, or proboscis, which gives
its name to the race. The size necessitates pillar-like limbs to
carry the weight, borne on rather primitive five-toed feet, al-
though there is a tendency toward the loss of one of the hinder
toes. The skeleton of the foot is encased in a yielding cushion
around which are nail-like hoofs which may be fewer in number
than the actual digits. Most long-limbed animals possess an
equivalent length of neck in order to enable them to reach the
ground. But not so here, for, because of the great, heavy head,
the neck is short and thick, and the proboscis serves the purpose
of food and water getting and other minor uses as well.

ADAPTATIONS OF SKULLS AND NOSES

The skull has changed its shape from the long, low form of
the average quadruped and has become short and high to gain
leverage w r ith which to wield the trunk and tusks. This only
in part involves the actual brain chamber which, in itself, has
over twice the capacity of a man's. The skull walls have become
enormously thick through the growth of cellular bone, known
as diploe, between the inner and outer surfaces of the original
skull bones. This has increased the leverage and the area for the
attachment of the neck muscles and ligaments without undue
increase in weight.

To the face is attached the proboscis, the combined upper
lip and nose through which the nostrils run for its entire length.
The organ contains some 500 muscles and possesses not only
great power but dexterity as well. In the Indian elephant it
terminates in one and in the African elephant in two finger-like
processes for grasping.

86 FOSSILS

PECULIAR DENTAL FEATURES

The proboscidean teeth are remarkable for their fewness
at any one time, their complexity of structure, and their manner
of succession in the jaws. There are in the adult elephant but
six fully formed teeth in the mouth, although when a grinder
is partly worn away its successor may be seen in partial use.
The tusks are long, curved, tapering teeth, originally the second
pair of upper incisors. These grow continuously throughout
the lifetime of the animal. The grinders are complex, being
formed of double plates of enamel, each pair enclosing a portion
of dentine and separated from the adjacent pair by a layer of
cement, the whole being bound together into a single organ. As
the softer dentine and cement are worn away, the enamel, being
by far the hardest, is left in the form of transverse ridges, thus
producing a roughened grinding surface. The number of ridges
varies from six to twenty-seven or more in a single tooth. These
grinders are formed successively in the rear of the jaws and move
downward and forward through the arc of a circle as the ones
in use wear away.

FROM MOERITHERIUM TO MASTODON AND ELEPHANT

The first proboscideans are found in the Egyptian Faiyum
desert, some sixty miles southwest of Cairo. The ancestral
form is Moeritherium, named after the ancient Lake Moeris, in
the sediments of which it came to light. Moeritherium was a
small Eocene form not over twenty-five inches in height, with
a long, low skull and the normal vertical tooth succession of a
mammal. There were three pairs of upper incisors of which
the second are already the largest. The grinders were simple,
short-crowned, with two or three cross crests. The proboscis
has not yet appeared; whether or not the animal even had a
prehensile lip is a matter of differing opinions. The body char-
acteristics are not well known.

Paleomastodon

Moeritherium was succeeded by Paleomastodon in the Lower
Oligocene of the same region, the former persisting for a while
with the newly arisen form. The skull of Paleomastodon is larger

Unknown common ancestor of Proboscideans,
Hyraces or Conies, and Sea Cows

Fig. 53 'rilYLOGKNY OF THE PROBOSCIDEANS

1, Moeritherium; 2, Paleomastodon; 3, Trilophodon; 4, Dinotherium; 5, Mastodon;

6, Dibelodon; 7, Stegodon; 8, Imperial Elephant; 9, Woolly Mammoth;

10, African Elephant; 11, Indian Elephant

Drawn to scale
(.Modified from Osborn who recognizes a number of divergent phyla, not here indicated}

88 FOSSILS

and its rear is higher. The nostril opening has receded backward
on the face, which means one of two things: either a proboscis
or an adaptation to aquatic life. Here apparently the former
is indicated, for the lower jaw, with its horizontal spade-like
tusks, is elongating, probably for use in digging, and a proboscis
is necessary to reach beyond it. The upper tusks are larger,
curve downward, and bear on their outer face a band of enamel
which is lacking in the modern elephant tusk, except for a tiny
patch at the end which is soon worn away. The skull, jaws, and
tusks of Paleomastodon show clearly that digging was a prime
function and determined the future tendency in evolution. The
grinding teeth are not unlike those of Moeritheritim, although
somewhat more complex. Paleomastodon was elephant-like in
body, so far as we know, although in neither of these Faiyum
forms was the entire skeleton discovered. It stood, perhaps,
three and a half feet in height.

The Four-tuskers

Out of the Paleomastodon comes a form variously known as
Tetrabelodon or Trilophodon, the former in allusion to its four
tusks, the latter to the number of cross crests on its interme-
diate grinders. The skull is large with well developed diploe,
and the tusks, while resembling those of Paleomastodon, are
much longer and still possess the enamel band. But the lower
jaw is unique in its great length, especially at the point of union
of the two halves which bore the usual spade-like tusks. With
the elongation of the jaw and the increased stature of the animal
came the corresponding development of the trunk. This could
be raised and swayed from side to side, but the jaw still impeded
its full use, as compared with that of existing elephants.

A large specimen of Trilophodon angustidens from the'Mio-
cene bed of Gers, France, may be seen in the Paris Museum of
Natural History. It was nearly as large as the Indian elephant.
Trilophodons were great migrants, spreading to Europe, India,
and even to North America, arriving there early in Miocene time.
They gave rise in turn to other four-tuskers, of which Tetra-
lophodon hdli from Nebraska possessed a jaw over six feet in
length ! The jaw having reached the maximum length com-
mensurate with utility, now shortens again and ultimately loses

FOSSIL ELEPHANTS AND MASTODONS 89

its tusks, a short, spout-like process on the chin of the modern
elephant being its final vestige. With the shortening of the
lower jaw the upper tusks curve upward instead of downward,
the enamel band being retained in Dibelodon and lost in the
true mastodons and elephants. The shortened jaw liberated
the trunk to full utility.

As with the horses, the proboscideans are not a single evolu-
tionary line; for there arose during Pliocene and Pleistocene
times upward of a dozen divergent races which throve for a while
then died out, except for the two existing elephant species. One
of these was Dibelodon, with short jaws and enamel-banded
tusks, and which survived in South America until recently.

THE AMERICAN MASTODON

The true mastodon, Mastodon americanm, came from the
Old World, but survived in the New until possibly within the
last thousand years or so. This was a stocky animal, up to
nine feet five inches high, with large, enamel-less tusks and
comparatively simple molars. The latter had four or five cross
crests, open in character, with little or no cement on the crown,
and two at a time in either jaw, or eight all told. The teeth
indicate a forest and savanna dwelling animal.

ADAPTATIONS AMONG ELEPHANTS

True elephants passed through transitional stages in the
evolution of their molars. The stegodonts had more numerous
cross crests than the mastodon; the valleys between grad-
ually became filled with cement and the crests increased in
number until the condition of the true elephant grinder was
reached. Stegodon was Asiatic, while Elephas was distributed
over Asia, Europe, and America, the somewhat more primitive
African elephant being called Loxodonta, from the lozenge-
shaped character of the molar crests.

All of these elephants have upturned, spiral, enamel-less
tusks and short lower jaws. These tusks are larger in Loxodonta
than in Elephas in fact there is a tendency on the part of the
modern Indian elephant toward the entire elimination of these
once useful organs.

90 FOSSILS

ELEPHANTS IN NORTH AMERICA

During Pleistocene time there were three more or less related
species of true elephants in North America, exclusive of the
mastodon. Of these the earliest was the Imperial elephant which
stood at least thirteen feet six inches at the shoulder, and whose
spiral tusks, which sometimes crossed at the tips, measured
thirteen feet to sixteen feet on the curve. In this elephant the
molars were coarsely ridged and had a thick coating of cement.
This species, Elephas imperator, is also known as the southern
mammoth and ranged from California to Texas and Mexico.
One tooth is recorded in French Guiana, which seems strange,
for no other true elephant is known in South America.

Elephas columbi, the Columbian elephant, is intermediate
in distribution as well as in evolution between imperator and
primigenius, the woolly mammoth, although its range to some
extent overlaps that of the other two and its teeth and other
characteristics seem to merge into those of the mammoth. In
old males it also possessed huge, spiral tusks which overlapped
at the tips. Its fragmentary remains are abundant throughout
the middle latitudes of the United States, but rarely does one
see a mounted skeleton of either columbi or imperator. The
Columbian elephant, with its eleven foot tusks stood over ten
feet, exceeding slightly the living Indian elephant but not equal-
ing the African.

THE WOOLLY MAMMOTH

The woolly mammoth is the most picturesque and perhaps
the best known of all prehistoric animals, for not only are
its frozen carcasses preserved to us, but it was seen alive
and depicted with admirable fidelity by the Paleolithic artists
of Europe. The mammoth was circumpolar in distribu-
tion, and its abundant fur adapted it for life amid glacial
and arctic cold. Judging from the perfection and profusion
of its remains, the mammoth, like the American mastodon,
must have vanished from the land of the living in com-
paratively recent times. Contrary to the impression gained
through our use of the term mammoth, Elephas primigenius was
not a large animal as elephants go, nine feet three inches being

FOSSIL ELEPHANTS AND MASTODONS 91

the maximum recorded height. The teeth were fine, with many
crests; in fact they possessed the greatest number in any species,
implying the final perfection of these complex organs. The
tusks, however, are of two sorts: huge, spiral ones and short,
nearly straight ones. This difference may either be a sex, age,
or varietal variation, but was probably the first.

THE TALLEST ELEPHANT

Elephas antiquns, the straight-tusked Mid-Pleistocene ele-
phant of Europe, had the greatest stature among proboscideans,
for it stood nearly fifteen feet in height, surpassing the great
African "Jumbo" by four feet.

A strange proboscidean of Miocene and Pliocene time in
Europe was Dinotherium, elephant-like in body and limbs, but
with extremely simple molars implying its descent from a form
not later than Paleomastodon, and probably earlier. The re-
markable feature, aside from the apparent total loss of upper
tusks, was the lower jaw, which was bent sharply at the front and
possessed a pair of curved tusks which pointed directly down-
ward. Dinotherium has given rise to much conjecture, especially
as to its habits of life. The general feeling is that it was largely
swamp-dwelling and used the tusks to dislodge its food. One
amusing notion was that Dinotherium was aquatic, lived in
rivers, and at night anchored itself to the bank with its tusks in
order to sleep comfortably.

SUMMARY

Thus the fossils tell us of the origin of the proboscideans out
of an ancestry common with the conies of Syria and Africa and
the sirenians or sea cows, of their first appearance in Moerithe-
rium of Egypt, of the successor Paleomastodon also of Egypt,
of their migration to Europe where the four-tuskers throve, and
of their subsequent migrations the world over, excepting to Aus-
tralia, Eurasia being the chief center of dispersal.

We see the grinding teeth increasing in complexity, except
in Dinotherium and Mastodon, and the second incisors of both
jaws developing into digging organs, the upper downwardly
curved, analogous to a pick, the lower to shovels. With the
development of the latter came the elongated nose and upper

92 FOSSILS

lip which were to form the proboscis. After reaching a me-
chanical limit of utility, the lower jaw turns downward, as in
Dinotherium, or shortens, as in all the other phyla. In the first
the upper tusks disappear, in the others they turn upward, be-
coming in extreme cases huge spiral organs which crossed at the
tips. Accompanying all this was the heightening and shortening
of the skull, for leverage, and a vast increase in bulk, until they
in turn become the largest of terrestrial mammals, as the dino-
saurs were the greatest among terrestrial reptiles, although the
former never equaled the latter in total tonnage; that has only
been attained and surpassed by the whales. It is interesting,
however, that, as with the horses, while many splendid lines have
passed away forever, a few remain for the interest and utility
of mankind.

CHAPTER IX

FOSSIL MEN

IT is strange how ready the average man is to accept as facts
the existence and interpretation of fossils as long as they
pertain to other animals or to plants, but how extremely skep-
tical he can be when fossil man is mentioned. This is due in
part to prejudice, whether inspired by religious beliefs or by
plain egotism, and also because of the extreme rarity of actual
fossils, especially in this country. In Europe one may go to each of
several museums the British Museum in London, the museums
in Paris, Berlin, Bonn, and Heidelberg among others where
he may see for himself the actual relics. But in America these
are necessarily illustrated by casts and reconstructions, all of
which are apt to inspire disbelief, rather than conviction, on the
part of the skeptical. This is due, of course, to the unique char-
acter of most of the material and the consequent fact that they
are so valued that American money cannot tempt the European
museum authorities to part with a single specimen. But to one
who has- seen and handled them these relics are as real and
authentic as are the fossil remains of any other forms of life,
and they are just as replete with information.

Fossil men have been found in China, Java, and South
Africa, but chiefly in Europe. They have been discovered in the
river drift, the sedimentation of such streams as the Elsenz in
Germany and the Ouse in southeastern England, and in limestone
caverns in various parts of France, Spain, Belgium, Germany,
and Austria. The former are the result of accidental inclusion,
possibly of drowned victims, the latter often are the result of
intentional burial in the deposits on the cavern floor.

In order of their antiquity, regarding which there is dif-
ference of opinion, the following discoveries of fossil species
belonging to the Hominidae, or family of men, may be men-
tioned :

FOSSILS

THE APE-MAN OF JAVA

(Figure 54)

Pithecanthropus erectus, the ape-man of Java, was discovered
in 1891-1892, in the river bed of the Sula Bengawan near Trinil,

Java. There were probably two
individuals, one represented by
the skull cap or calvarium, three
teeth, and a left thigh bone, the
other, found some miles away,
consisting of a portion of the
lower jaw. Their age is about
500,000 to 1,000,000 years.

Pithecanthropus possessed a
low skull vault with immense
beetling brows and a cranial ca-
pacity about two-thirds that of
modern man. The thigh, how-
ever, was straight, and indicates
how long erect posture has been
a trait of mankind. This ape-

(Pithccanthropns credits)
This species, while in a sense annectant

for a

form

From a restoration by the author, after aSCCttt but Was a

McGregor ( ....

aside from the original Asiatic

birthplace of mankind, to endure for a while, and then to suffer
extinction as a race.

THE HEIDELBERG MAN

(Figure 55)

Homo heidelbergensis, the Heidelberg man, was found in
1907 in the river sands at Mauer, Germany, near the town whose
name it bears. This fossil consists of a perfect lower jaw with
complete dentition, and its age is estimated at about 400,000
years.

The Heidelberg man, also, possessed a massive, ape-like
jaw, but essentially human teeth. More of the skeleton has
not yet been revealed, but he was doubtless ancestral to the
Neanderthal man and must have possessed a comparable, al-
though somewhat more primitive cranium, as the conjected
restoration shows,

FOSSIL- MEN

THE PILTDOWN MAN:

" (Figure 56)

Eoanthropus daws only the
Piltdown man, from the river
drift in the valley of the Ouse,
Sussex, England, was discov-
ered in 1912. Again there
were two specimens, found
some four miles apart the first
including portions of the skull
and teeth, together with the
left half of the lower jaw. The
second specimen, much less
perfect, served to corroborate
the association of the human
cranium with the ape-like lower
jaw, about which there had
been considerable difference of
opinion. Their age is 275,000
to 400,000 years.

Fig. 56 THE PILTDOWN MAN
(Eoanthropus dawsoni) ^/

The skull is superficially of man-like appear-
ance, although it is also ape-like, especially
in the rear and in the inward slope of
the sides. The contained brain, however, '
is not only small, but the most primitive
and ape-like one hitherto recorded

From a restoration by the author, adapted
from McGregor

Fig. 55 THE HEIDELBERG MAN
(Homo heidelbergensis)

This species seems to be in the line of

ascent with the Neanderthal man of later

time

From a restoration by the author, adapted
from McGregor

The Piltdown man had a
high, steep forehead without
beetling brows, so that while
the cranium was quite man-like,
the jaw, on the contrary, was
ape-like, as was also the brain.
We cannot as yet visualize the
whole of the Piltdown man.

THE PEKING MAN

Sinanthropus pekinensis,
the Peking man, came from
cave deposits at Chow Kow
Tien, twenty-five miles south-
west of Peking (Peiping),
China. In 1921 two teeth
were discovered, and in 1930 a
fine calvarium* and other

* Calvarium, the domelike upper portion of the skull.

FOSSILS

parts, and later another skull, were brought to light, but the
explorations are not yet complete and will undoubtedly yield
further material. Their age is difficult to determine; but from
the associated fossil animals they were possibly contemporaneous
with the ape-man of Java and the Piltdown man. The Peking
man is also of the Neanderthal type, with its beetling brows.

Then, after a lapse of thousands of years, come the cave
men of Europe and Africa, including the most completely known
of fossil men. These are:

THE NEANDERTHAL MAN

(Figure 57)

Homo neanderthalensis (or primigemus] , the Neanderthal
man, is known also as the Mousterian man from his stage of
culture. The first discovery was made at Gibraltar in 1848.
Others were made at: Neanderthal, Germany, in 1857; Spy,
Belgium, in 1886; and at a number of other localities, including
Chapelle aux Saints, and Aix la Chapelle, Gibraltar, and finally
in 1924, 1931, and 1932 in Palestine. Altogether there are some
forty individuals showing racial distinctions within the species.

Their age is estimated at 25,000
to 40,000 years B.C.

Neanderthal man is now one
of the best known of fossil men,
and we can visualize him in his
entirety. He was short of stat-
ure, stocky, but with a slouching
gait and a huge bestial head
thrust forward, with low skull
vault and beetling brows. He
seems to have been the culminat-
ing member of a long-lived race
which as such has ceased to be,
although because of possible
Fig. BY-TOE NEANDERTHAL MAN cross ; n g w j t h Cro-Magnon man,

(Homo ncanderthalensis')

A r i u i c t M IT some of his blood, greatly di-

One of the best known of fossil men. He i

was probably the culminating member of l u ted, may Still exist. He had
a long-lived race which, as such, has ceased ' J

to be fire and practiced reverential

From a restoration by the author, adapted k,, r : n 1 hirli cppmc f-r imnlv
from McGregor and Boule DUrial, WHICH SCCIUS CO imply

FOSSIL MEN

some conception of existence beyond physical death, whatever
the form of that concept may have been.

THE RHODESIAN MAN

(Figure 58)

Homo rhodesiensis, the Rhodesian man, from a cavern at
Broken Hill mine in northern Rhodesia, Africa. Here again
two specimens were discovered in 1Q21 - nnp nf
skull with complete dentition
and other parts but no lower
jaw. The Rhodesian man can-
not be dated with accuracy but
is fully fossilized and u of re-
spectable antiquity." He also
had beetling brows and belonged
to the Neanderthal group.

MODERN MAN

(Figure 59)

Homo sapiens is the existing
species to which all men and Fig> 0ff _, rilJi RHODESIAN MAN

(Homo rhodesiensis)

This fossil man was found in association
with animals which are either now alive in
Africa, or were alive at the advent of the
big-game hunters, and this seems to imply a
comparatively recent date

prom a restoration by the author, after
Smith Woodward

women belong, of whatever
race, from the highest to the
lowest. Of this species the old-
est race is that of Cro-Magnon
man discovered in Gower,
Wales, in 1823; at Aurignac,
France, in 1852, and especially
the type material at Cro-Mag-
non, Dordogne, France, in
1868. It is a widespread va-
riety of which many perfect
specimens are known and which
lived in Europe as far back
as 25,000 B.C.

Fig. 59 THE CRO-MAGNON MAN

(Homo sapiens)

Crd-Magnon man may well be called the
summit of human evolution. All his fea-
tures are diagnostic of our species in its

finest expression

From a restoration by the author, after
McGregor

98 FOSSILS

Cro-Magnon man may well be called the summit of human
evolution. Averaging over six feet in height, erect of carriage,
and with a splendid head, this man must have looked with dis-
dain upon the Neanderthals whose distribution in time and space
he overlapped. The beetling brows are gone, the forehead is
high, the chin jutting and pointed; all his features are diagnostic
of our species in its finest expression.

The above is a very impressive list and compares favorably
with many another group of fossil organisms both as to variety
and perfection of material, and is worthy of the utmost respect
and credence.

WHENCE CAME THE FOSSIL MEN OF EUROPE?

It is supposed that the fossil men of Europe represent a
series of invading waves along several corridors of migration
from their racial homes in Asia, for the evidences point strongly
to Asia rather than to either Europe or Africa as the place of
origin of the human family.

For a detailed account of human origins see u The Coming
of Man" in this Series.

CHAPTER X

EXTINCTIONS AND THEIR CAUSES

WE HAVE spoken several times of the extinction of various
forms of life. The older authorities who accepted the
doctrine of creationism could not understand how any race of
animals created directly by the Almighty could possibly have
passed out of existence unless destroyed by the hand of man,
for even if animals represented by fossils in a given locality
were no longer in existence in that particular region, there was
no proof that they did not still exist in some unknown portion
of the globe. Thomas Jefferson, the third president of the
United States, wrote the first paper on paleontology published
in America. This paper, which appeared in 1799, was entitled
"A Memoir on the Discovery of Certain Bones of a Quadruped
of the Clawed Kind in the Western Parts of Virginia/' This
creature Jefferson took to be some gigantic cat-like animal which
he named Megalonyx in allusion to its great claws and believed
to be yet alive in the fastnesses of Virginia. The world has
been so thoroughly explored now that the discovery of a large
unknown terrestrial mammal is a very remote possibility, the
curious Okapi, a giraffe-like form from Central America, an-
nounced by Sir Harry Johnston in 1901, being the last such
discovery. Hence one is justified in the assumption that many
magnificent types among animals, as well as countless obscurer
forms, have utterly passed away. Perhaps the first real recog-
nition of this extinction was made by the French naturalist,
Georges Cuvier; in explanation of the fossil animals from the
gypsum quarries he invoked the theory of Catastrophism.* We
know that several forms of life have been locally destroyed by
man, as the wolves and boars in England, and we also know
that in some cases man has been responsible for total extinc-
tions, as in the case of the passenger pigeon, the dodo, the great

* See page 31 in "The Earth" in this Series.

100 FOSSILS

auk, and Steller's sea cow. We are also aware that, unless
preventive measures are speedily taken to avert it, the racial
life of the great whales will soon cease, as an outcome of the
relentless slaughter of the Antarctic fisheries. We, as scientists,
are just as fully convinced of extinctions through natural causes.

Two FORMS OF EXTINCTION

Extinctions are of two sorts which may be compared to the
death of two men, one a celibate, the other not. Both have
received their life and heritage through an unbroken line from
the beginning of life on earth, but for the celibate who dies
without issue, his line ceases forever, while the other, although
as an individual he has ceased to be, yet lives in his children.
Extinction can be by racial death, comparable to the celibate, or
by transmutation, where a species as such has ceased, but its
blood still flows in the veins of its altered descendants.

There were, during Miocene time, as we have seen, several
lines of horse evolution, two of which are represented by Hypo-
hippus, the browsing horse, and Merychippus, the first true
prairie horse. Hypohippus was the celibate race which died
utterly and out of which no new equine genus arose ; Merychip*
pus, on the other hand, was immortalized in its descendants,
for, through Pliohippus and Plesippus, it gave rise to Equus
which still survives, although not in the form of Merychippus,
for that animal is, from the standpoint of immediate existence,
just as extinct as the other. The word transmutation is more
or less synonymous with evolution, so that a discussion of the
causes leading to Merychippus extinction would embrace a dis-
cussion of the entire problem. With Hypohippus, on the other
hand, if any single cause would suffice, it would be Miocene
aridity with a lessening of the sort of vegetation to which its
short-crowned, browsing teeth were adapted, with consequent
racial starvation. In general, although environmental change is
in the main a prime cause of extinction of either sort, one is in
error if he is content with so simple an explanation as that.
For the environment of an animal, physical and biotic, is so
complex that he is menaced upon every side, so that generally the
initial cause need do no more than begin the destruction, and

EXTINCTIONS AND THEIR CAUSES 101

when the numbers are reduced beyond a critical point extinction
is sure to follow.

CHANGES IN PHYSICAL ENVIRONMENT

Dr. Osborn has summarized the causes of racial extinction,
his study of the problem being based on both existing and fossil
forms, but largely the latter. First in importance are changes in
the physical environment wrought by the elevation and subsidence
of land masses, with the resultant formation or severance of
land bridges. These would either permit or inhibit migration.
The first may allow the incursion of hostile animals into an
environment, to the detriment of the native population. The
second may result in increased competition which the weaker
forms could not resist. On the other hand, isolation may per-
mit forms to survive long after their extinction elsewhere, as
in the case of the Australian marsupial fauna.

Increasing cold has been a very potent cause of extinction,
for while some vigorous animals, like the musk ox, may be able
to adapt themselves to it, others will fail to do so. Its reaction
on cold-blooded air-breathers amphibians and reptiles is ob-
vious. Increasing moisture changes the face of nature, producing
more swamp and jungle and the number of insect pests which
may be the transmitters of disease. It would cause the diminu-
tion of the grassy steppe-like lands, and thus be inimical to
horses and other grazing forms, just as the spread of the
prairies due to increasing aridity would affect the browsers.
A specific instance of the result of widespread aridity would be
the extinction of early primates in North America, at the close
of the Eocene period. Now, except for mankind, there are no
primates found north of the edge of the Mexican plateau,
although south of it, where the climate changes abruptly into
the warm, moist conditions of the tropics, they are still abun-
dant and are the actual descendants of those which formerly
lived farther to the north.

CHANGES IN BIOTIC ENVIRONMENT

Competition is inseparable from life and is a potent stimulus
to evolution, but the competition caused by the incursion of new
adaptable forms may, as we have seen, prove fatal to the inadapt-

102 FOSSILS

able. Restrictions of island life with reduced food supply has
seemingly been the cause of racial dwarfing, as the Shetland
ponies or the dwarf elephants found as fossils in the islands
of Cyprus and Malta in the Mediterranean. Introduction of
destructive grazing animals and rabbits, or of such carnivores
as the Dingo dog into Australia, may render extinct many of the
ancient fauna, either indirectly through diminution of the food
supply or through direct destruction.

INTERNAL CAUSES

There are also internal causes, such as the inadaptive feet,
teeth, and brain of the archaic mammals. Large size and slow
maturity, together with few young, may make competition with
smaller, highly prolific animals unendurable. Thus, as Dr.
Osborn has said,* by way of summation: u Following the diminu-
tion in number which may arise from a chief or original cause,
various other causes conspire or are cumulative in effect. From
weakening its hold upon life at one point an animal is endan-
gered at many other points. "

^American Naturalist, vol. XL, page 859.

CHAPTER XI

THE UTILITARIAN VALUE OF FOSSIL REMAINS

As WE have seen, fossils are of prime importance in deter-
mining the age of the strata wherein they are found, and
while, from the standpoint of the man of business, this may
seem of little practical moment, other than its educational value,
it is nevertheless indirectly of the greatest use.

FOSSILS AN INDEX TO OIL AND COAL

Two of the most important mineral substances, both of
which are of organic origins, are oil and coal. Oil geology, to
determine whether or not a certain area would be productive
and therefore pay for the expense of elaborate drilling, depends
in part on structure of the earth's crust, but more and more is
it dependent upon the fossils themselves. For oil may be found
in strata of certain geologic periods, whereas others are invari-
ably barren. Should certain strata prove oil-bearing in one
region, it is necessary to determine what is known as correlation
in another region in order to predict the possibility of the occur-
rence of oil there. Not only have the larger fossils proved of
value as correlators, but the micro-organisms, such as the tiny
shells and tests of Foraminifera among the Protozoa, have proved
to be splendid index fossils. Hence in well-drilling the cores
are carefully examined and not only the contained microfossils
but the order of their occurrence determined. A drilling from
the new site, if it compares in its fossil contents with that from
the old, will form a basis for an estimate of yield and consequent
values. A paleontologist, especially one familiar with the tech-
nique of core determination, is today an essential part of the
organization of every oil company.

In a similar manner, both large and small fossils are used
to follow productive coal seams. Profitable coal beds would not
be found associated with Silurian fossils; on the contrary, certain

103

104 FOSSILS

Cretaceous fossils would at once indicate the likelihood of coal-
bearing strata. The same is true of other mineral products,
iron ore, building stone, and the like.

A LEGAL ILLUSTRATION OF FOSSIL IMPORTANCE

A single case will illustrate the use of fossils in a legal sense.
"New York State once called for estimates on the construction
of a section of highway, stipulating that samples of the stone
to be used be submitted with the estimates. A certain contract-
ing company submitted a satisfactory estimate and produced
specimens of a stone of high quality. The contract was signed
and the road building began. When the work was finished, it
did not give satisfaction and the State refused payment on the
ground that the contractors had used a grade of stone inferior
to that agreed upon. The contractors sued the State for their
money; but, unluckily for them, the sample they had submitted
with their original estimate contained a fossil which fixed its
geological age exactly. The State was able to prove that no
rock of that age existed in any of the quarries from which the
contractors had obtained the stone they finally used. One fossil
cost the contractors dearly." (C. P. Berkey, in Geology from
Original Sources.)

FOSSILS A SOURCE OF PETROLEUM*

According to our original definition of a fossil, it may be
either the actual animal or plant, or the product of the activity
of the organism. Although in a strict sense the various hydro-
carbons are not in their original recognizable shape, yet they
are organic products and as such approach near enough to our
subject to be worthy of mention. They include natural gas
and petroleum as well as the various coals, from peat to anthra-
cite and graphite. The coals are clearly of plant origin, while
oils and gas may be either animal or plant products.

When organic beings die and decay sets in, the resultant ma-
terials are returned to the air or the dust of the earth, if the dis-
integration takes place while exposed to the atmosphere. Hence
pure continental deposits contain little or no commercial petro-

* Adapted from Pirsson and Schuchert, Text-book of Geology, volume 2,
page 254.

UTILITARIAN VALUE OF FOSSIL REMAINS 105

leum unless it has seeped into them from adjacent oil-bearing
strata. When water-borne sediments, whether of fresh or
marine origin, are subject to repeated weathering during their
deposition, the contained hydrocarbons are oxidized, and hence
they, too, lack paying quantities of oil. That this has happened
is indicated by the color of the strata, red or reddish, yellowish
or white, and by the presence of meteorological records such as
rain prints or sun cracks.

Under water, especially of the sea, not only is the disin-
tegration of the organism slow, but the fats are liberated as
tiny oil droplets which rise to the surface and are lost in clearer
waters, particularly if the latter are in motion, for this assists
oxidation. If, on the other hand, the waters are muddy and
still, the oil droplets will adhere to the mud particles and thus
sink to the bottom and be buried by subsequent material and
hence preserved. This deposited mud ultimately forms dark
bituminous shales, the darkness of their color indicating the
presence of oil. These black shales, although forming a small
percentage of the shales as a whole, are nevertheless the u mother
rocks" of petroleum, which may be extracted by distillation. The
natural liberation of the petroleum into pockets of fluid oil and
gas is evidently due to the pressure of capillarity which sets
the oil free.

Our whole civilization in this so-called u machine age" is
based largely upon these hydrocarbon products of bygone animals
and plants, which form the chief motivating agent of the present
time. Their value to mankind is therefore inestimable.

SUGGESTIONS FOR FURTHER READING

Prepared by the Author

GEOLOGY FROM ORIGINAL SOURCES William M. Avar, Richard F. Flint and

Chester R. Longivell HOLT

A collection of collateral readings presented in an extremely interesting and original manner.

THE EVOLUTION OF THE EARTH AND MAN George A. Baitscll YALE

A collection of essays upon the evolution of the earth and its inhabitants including mankind,
written by twelve men each of whom has specialized along the subject of his essay.
Particular attention is called to Chapter II. by Charles Schuchert, on "The Earth's
Changing Surface and Climate," and Chapters IV and V on "The Pulse of Life" and
"The Antiquity of Man" by R. S. Lull.

THE EVOLUTION OF THE HORSE Frederic B. Loomis JONES

A fully illustrated book, by a practical paleontologist, on the origin and history of the horse.

ANIMALS OF THE PAST Frederic A, Lucas AMERICAN MUSEUM

Charmingly written by one who not only knew his subject but through long experience
knew how to present his facts to the layman.

TRIASSIC LIFE OF THE CONNECTICUT VALLEY Richard S. Lull

Bulletin No. 24 of the Connecticut State Geological and Natural History Survey. An
illustrated discussion of the footprints and skeletal remains of the creatures which populated
the Connecticut Valley during the Age of Reptiles.

ORGANIC EVOLUTION Richard S. Lull MACMILTAN

A fully illustrated textbook of evolution. Part III deals particularly with the evidences
for evolution derived from the fossil record.

THE WAYS OF LIFE Richard S. Lull HARPER

An expansion of the theme of "The Pulse of Life" in The Evolution of Earth and Man.

ANCIENT MAN Richard S. Lull DOUBIEDAY

One of the Humanising of Knowledge series, dealing principally with fossil human species.

HUMAN ORIGINS George Grant MacCurdy APPLETON

One of the most highly authoritative books on this subject in the English language.

THE LIVING PAST John C. Merriam SCRIBNER'S

A small book of essays on paleontological subjects, one of which discusses the remarkable
tar pits of Los Angeles.

MEN OF THE OLD STONE AGE Henry F. Osborn SCRIBNER'S

Fully illustrated from first hand sources.

ORIGIN AND EVOLUTION OF LIFE Henry F. Osborn SCRIBNER'S

A learned volume based in large part upon the fossil record. Time and opportunity
have given Professor Osborn an insight into this field possessed by few men.

TEXTBOOK OF GEOLOGY: PART II, HISTORICAL GEOLOGY C7iar/<>j Schuchert

WILEY
A fine exposition of prehistory from stratigraphical and fossil evidence, by a high authority.

THE EARTH AND ITS RHYTHMS Charles Schuchert and Clara M. LeVcne APPLETON
An eminently readable book produced "by the process of filtering a great mass of geologic
detail through a non-scientific mind."

AN INTRODUCTION TO THE STUDY OF FOSSILS Hervcy W. Shimcr MACMILLAN
A valuable textbook of paleontology interpreted through the study of existing forms.

TEXT-BOOK ON PALEONTOLOGY Karl A. von Zittel MACMILLAN

Translated and edited by Charles R. Eastman in collaboration with a corps of seventeen
specialists. Still the standard textbook of paleontology.

106

SUGGESTIONS FOR FURTHER READING 107

KEY TO PUBLISHERS

AMERICAN MUSEUM American Museum of Natural History, Columbus Avenue and 77th

Street, New York, N. Y.

APPLETON D. Appleton & Company, 29-35 West 32nd Street, New York, N. Y.
DOUBLEDAY Doubleday, Doran & Company, Garden City, N. Y.
HARPER Harper & Brothers, 49 East 33rd Street, New York, N. Y.
HOLT Henry Holt & Company, Inc., 1 Paik Avenue, New York, N. Y.
JONES Marshall Jones Company, 212 Summer Street, Boston, Mass.
MACMILLAN The Macnullan Co., 60 Fifth Avenue, New York, N. Y.
SCRIBNER'S Charles Scribner's Sons, 597 Fifth Avenue, New York, N. Y.
WILEY John Wiley & Sons, Inc., 440 Fourth Avenue, New York, N. Y.
YALE Yale University Press, 143 Elm Street, New Haven, Conn.

GLOSSARY

[Only those terms are defined in this glossary which either are not
explained in the text or are explained once and are used again several
pages away from the explanation.]

ARTICULATION: a state of being joined.
ARTIFACT: a product of human workmanship.
COPROLITES: a fossil excrement.

HORIZON: the deposit of a particular time, usually identified by distinctive
fossils.

INDEX

WITH PRONUNCIATIONS t

Aden Crater, New Mexico : ground sloth
found at, 7*

Agate Spring Quarry, Nebraska: pro-
fusion of fossils in, 31, 35*

Age of fossils, 4, 18

Aix la Chapelle (eks-la-sha"pel') France,
96

Algae: limestone reef fossils, 28; land
plants originated from marine, 49

Allosaurus (aT'o-so'rus), 59

Amber-preserved fossils, 7

Amblypods (am'bli-pods) : primitive
herbivorous mammals, 74, 75*; gro-
tesque forms, 76

Ameba, 41

Ammonoids (am'6-noids) : extinction,
41 ; shells, 1

Amphibians : effect of climate on, 101 ;
fossil, 27; of Carboniferous times,
38; place in evolution, 55

Anchitherium (an"ki-the'ri-um), 82,
83

Andrews, Roy Chapman (1884- ),
American zoologist and explorer,
16, 38, 74

Andrewsarcus (an-droo-sar'kus), 74

Ankylosaurus (an"ki-16-s6'rus), 62

Ant in amber, 8*

Antelopes, Fossil, 24

Ape-man of Java, 94*

Archaeopteryx (ar"ke-6p'ter-iks) : fos-
sil, 30; transitional character, 67 ; 68*

Archimedes bryozoan (ar"ki-me'dez
bri"6-zo'an), 53

Armored dinosaur, 59*

Arthrodires (ar"thro-dirs), 52

Artifacts, 15

Asphalt beds, 27

Asses, 84

Atlantosaurus (at-lan"to-s6'rus), 20

Auk, 100

Aurignac (a"re"nyak'), France, 97

Barbados (bar-ba'doz) Island fossil
deposits, 22

Barosaurus (bar"6-so'rus), 59

t For key to pronunciation, see page 114.
* Asterisk denotes illustration.

Bavaria fossil beds, 28

Bees, 56

Beetles, 56

Belemnite (beTem-nit) shells, 14

Beresovka (bar"e-z6f'ka) mammoths,
5*, 6

Biogenetic Law, 43

Birds, Fossil: description of, 67; in
Bavaria, 29; toothed, 25, 69

Boars, 99

Bohorodcrany (b6"h6-rod-cha'm) rhi-
noceros, 6

Bone Cabin Quarry, Wyoming, 35,
36*

Brachiopods (brak'i-6-pods) : Devoni-
an, 52 ; Ordovician, 50*

Bridger Lake deposits, 25, 74, 75, 76

Brontosaurus (bron"t6-s6'rus) : de-
scribed, 58* ; extinction, 60 ; skeleton,
frontispiece; upper Jurassic remains,
36*, 37

Bryozoans (bri"6-zo'ans), 53, 54*

Buffalo, Fossil, 24

Bugs, 56

Butterflies, 56

Caddis worms, 16

California asphalt beds, 27

Cambrian (kam'bri-an) period, 35, 45

Camels, Fossil, 27, 32 ;/ 33*

Camptosaurus (kamp"to-s6'rus), 60*

Carboniferous (kar"bon-if'er-us) pe-
riod : coal swamps, 27 ; coprolites, 15 ;
fossils, 53; trees, 37

Cast type of fossils, 10, 12*, 13*

Catastrophism theory, 2, 99

Celebes (seTe-bez) Island fossil de-
posits, 23

Cenozoic (se"no-z6'fk) era : fossil his-
tory of, 25, 72; petrified mammal
bones, 9

Ceratopsia (ser"a-top'si-a) : appear-
ance, 63*; fossil beds, 20

Chain coral, 48*

Challenger expedition, 23

Chapelie aux Saints (sha"peT 6 san'),
France, 96

Chasmosaurus (kas"m6-so'rus), 11*

Cheops, Pyramid of, 18

109

110

FOSSILS

Climate : influence on organic life, 55 ;
stimulating nature of variable, 77;
warm-blooded animals possibly pro-
duced by glacial cold, 56 ; as a cause
of racial extinction, 101

Coal : fossil animals an index to, 103 ;
fossil deposits, 27, 54

Columbian elephant, 90

Como Bluffs, Wyoming, 20, 37, 71

Comparative anatomy : defined, 42

Compsognathus (komp-sog'na-thus),
30*, 31, 64

Condylarths (kon'di-larths"), 74, 75*

Conies, 91

Connecticut : Triassic rocks, 13 ; Cre-
taceous carnivores, 64

Continental shelf fossil deposits, 21

Converse County (Calif.) fossil beds,
71

Cope, Edward Drinker (1840-1897),
American paleontologist, 74

Coprolites (kop'ro-Hts), 14

Coral, Chain, 48

Corals: Cambrian, 45; Devonian, 52;
Ordovician, 50 ; Silurian, 48

Coryphodon (ko-rif'6-don), 75*

Coyotes (ki-6'tes), Fossil, 27

Crab, Horse-shoe, 29*

Creodonts (kre'6-dont), 73, 74*

Cretaceous (kre-ta'shiis) period : fos-
sil history of, 60; strata names, 20;
globigerina, 24; North American in-
land sea, 25

Crinoids (kri'noids), 53*

Crocodiles : aquatic habits acquired,
65; Bone Cabin Quarry remains, 37;
delta fossils, 24; lithographic stone
fossils, 29

Cro-Magnon (kr6"ma"nyon') man :
description of, 97* ; possible crossing
with Neanderthal man, 96

Crustaceans (krus-ta'shans) : fossilized
trails, 13; trilobites ancestral to,
49

Cuttle-fish, 29

Cuvier (ku"vya'), Georges (1769-1832),
French naturalist, 99

Cycad (si'kad) plants : fossilized, 9* ;
histometabasis illustrated in, 10

Cynodont (si'no-dont), 70

Cyprus, Island of, 102

Darwin, Charles (1809-1882), English
naturalist, 43

Dean, Bashford (1867-1928), American
zoologist, 10

Delta fossil deposits, 24

Devonian (de-vo'm-an) period: fossil
history of, 10, 13, 16*, 51 ; vertebrate
and invertebrate life during, 51, 52

Dibelodon (di-bel'6-don), 89

Diceratherium (di"ser-a-the'ri-um),
31*, 32

Diceratops (di'ser-a-tops"), 64

Dingo dog, 102

Dinoceras (di-nos'er-as), 76*

Dinohyus (di'no-hi"us), 32*

Dinosaurs (di'no-sors) : armored, 59* ;
beaked, 62*; duck-bill, 61*; evolu-
tion, 57, 60 ; fossilized trails, 13, 14* ;
found at Bone Cabin Quarry, 35 ;
found at Como Bluff, 37; from Al-
berta, 62; horned, 63*; petrified
bones, 9; range, 57; skin impressions,
10, 11*; smallest recorded, 30*, 31;
Upper Jurassic remains, 20, 35

Dinotherium (di"no-the'ri-uni), 91, 92

Dipnoans (dip"no-ans), 52

Dodo, 99

Dogs: from Pompeii, 12*; the dingo,
102

Dolphins: natural casts of, 11 ; modern
forms resemble old reptiles, 14

Dragonflies : gradual metamorphosis,
56 ; Carboniferous, 55 ; Upper Juras-
sic remains, 29

Dromocyon (dro-mo'ci-on), 74*

Duck-bill dinosaur, 61*

Dune dwellers of Mongolia, 16

Eichstadt (ik'stet) fossils, 29

Elephants : adaptations, 89 ; African,
87, 89; American, 90; asphalt-bed
fossils, 27; Columbian, 90; dwarf,
102; evolution, 41, 77, 85, 91; Im-
perial, 90; Indian, 85, 88, 89, 90;
largest, 90, 91; phylogeny, 87*;
teeth and tusks, 86, 88, 89

Elsenz River fossils, 93

Eoanthropus dawsoni (e"6-an'thrd-pus
da'son-i), 95*

Eocene (e'6-sen) period : elephants,
86; horses, 80; marine life, 18, 39*;
North American primates, 101

Eohippus (e"6-hip'us) : ancestry, 74;
appearance and range, 80

Epihippus (ep"i-hip'us), 82

Equus : see Horses

Estuarine (es'tu-a-rm) deposits, 24

Evolution : an orderly process, 19 ;
continental shelves the "hotbed" of,
22; main lines of evidence, 42;
mammalian, 73, 94, 100; substanti-
ated by fossils, 3, 41

Extinctions : artificial causes, 99 ; nat-
ural causes, 78, 100; mark the close
of each era, 72; of the American
horse, 83; of the great reptiles, 71

Faiyum (fi"yoom') fossil beds, 41, 86.
88

INDEX

111

Fishes: Carboniferous, 27; chalk bed
fossils, 25 ; Devonian period, 51 ;
Eocene, 39*; ganoid, 52; natural
casts of fossil, 11; Silurian, 51

Flies, 56

Flood-plain fossil deposits, 25

Florida manatee, 41

Footprints, Fossil, 13*, 14*

Foraminifera (fo-ram"i-nif'er-a), 103

Ganges delta fossil deposits, 24

Ganoid fishes, 52

Gas sources, 104

Gazelle camel, 27, 32, 33*

Geology: chronological chart, 46;
great natural revolutions, 72; lines
of period demarcation in strata, 19;
marred records, 17; stratigraphical,
20

Gers (zhar) fossil bed, 88

Giant swine, 32*

Gibraltar human fossils, 96

Glacial period, 83

Globigerina (glo-bij"er-i'na) : builder
of limestone, 23* ; vast areas covered
by, 24

Gower, Wales, 97

Grand Canyon strata sequence, 19

Graptolites (grap'to-Hts) : dominant in
the Ordovician period, 49* ; extinc-
tion, 41

Grasshoppers, 56

Ground sloths : see Sloths

Guano (gwa'no) preserved fossils, 7

Gypsum Cave, New Mexico, 7

Haeckel, Ernst (1834-1919), German
biologist, 43

Hairy mammoth, 5

Heidelberg man, 94, 95*

Hesperornis (heY'per-or'ms) : fossil
remains of, 25 ; appearance, 69*

Hilderbergian formation, 54

Hipparion (hl-pa'ri-on), 83

Hippopotami fossils, 24

Histometabasis (his"t6-me-tab f a-sis) :
denned, 9; examples, 10

Homo heidelbergensis (ho'mo hi"del-
bcrg-en'sis), 94, 95*

Homo neanderthalensis (ho'mo na-
an"der-tal-en'sis), 96*

Homo primigenius (ho'mo pr!"mT-
je'nT-us), 96*

Homo rhodesiensis (ho'mo ro-de"zT-
en'sis), 97*

Homo sapiens (ho'mo sa'pi-enz), 97*

Horned dinosaurs, 62, 63*

Horses: evolution, 77, 79, 81*; extinc-
tions, 83, 100 ; fossils in asphalt bed,
27

Horse-shoe crab, 29*

Huxley, Thomas Henry (1825-1895),
English biologist, 4

Hypohippus (hi"po-hip'us), 83, 100

Hyracotherium (hi"ra-k6-the'ri-um),
80

Ice-preserved fossils, 5*

Ichthyornis (ik"th!-6r'ms) : fossil re-
mains, 25 ; resemblance to terns, 69

Ichthyosaur (ik'thi-6-sor) : appear-
ance, 66* ; habits, 65 ; coprolites, 14

Iguanodon (i-gwan'6-don), 61, 62*

Imperial elephant, 90

Indian elephant: size, 88, 90; tusks, 89;
proboscis, 85

Insects: amber-preserved, 8; Carbon-
iferous, 27; development of wings,
55; effect of climatic changes on,
55 ; fossilized trails, 13 ; trilobites
ancestral to, 49

Invertebrates : conquer the land, 52 ;
first flying species, 55; in the Or-
dovician period, 49

Iron ore, 104

Java: fossil men in, 93, 94

Jefferson, Thomas (1743-1826), Ameri-
can statesman and president of the
United States, 99

Jellyfish: biological phylum, 49; Cam-
brian, 35; lithographic stone fossils,
29 ; natural mold of, 12*

Johnston, Sir Harry (1858- ), Eng-
lish scientist and author, 99

Jurassic (joo-ras'ik) period : dinosaurs,
35 ; fossils, 58 ; limestone reef de-
posits, 28; lithographic quarries, 29;
strata names, 20

Karoo formation, 70

Konigsberg amber, 8

Lake fossil deposits, 26

Lamna sharks, 23

Lance formation, 20

Laramie fossil beds, 20

Lena River delta mammoth, 5

Limestone : built by globigerina, 23* ;
nummulitic, 18*

Lions, Fossil, 24

Lizards, 65

Locations of fossils, 21

Los Angeles, Calif., 26, 27

Loxodonta (16k"s6-don'ta), 89

Malta, Island of, 102

Mammals : archaic, 71, 72, 78 ; domi-
nant in the Cenozoic era, 72; essen-
tials of development, 73; modernized,
77, 99; origin of warm-blooded, 70;
petrified bones of, 9

Mammoths: described, 90; hairy, 5;
ice-preserved, 5; oil-preserved, 6;
southern, 90; tusks, 6; woolly, 87,
90

112

FOSSILS

Man: artifacts, 15, 19; biogenetic law
illustrated in, 42; evolution, 77, 98;
fossil, ,93

Manatee, Florida, 41

Marine fossils : Bavarian, 28 ; Carbon-
iferous, 53; continental shelf, 21;
deep sea, 22 ; inland seas, 25 ; strand,
22

Marsh, ^Othneil Charles (1831-1899),
American paleontologist, 20

Mastodons: American, 89; evolution,
85; four-tuskers, 88; peat swamp
fossils, 26; phytogeny, 87; teeth, 91

Matthew, Dr. William Diller (1871-
1930), American paleontologist, 71

Mazon Creek coprolites, 15

Megalonyx (meg"a-16n'iks), 99

Memoir on the Discovery of Certain
Bones of a Quadruped of the Clawed
Kind in the Western Parts of Vir-
ginia, A, 99

Merychippus (mer"i-kip'us), 83, 100

Mesohippus (mes"6-hip' u s), 82

Mesozoic (mes"6-zo'ik) era; coprolite
remains, 13; cycads, 10; life in, 56;
petrified dinosaur bones, 9

Millepedes (mil'e-peds) : of Carbonif-
erous times, 37; trilobites ancestral
to, 49

Miocene (mi'6-sen) era: dolphin, 11;
elephants, 88, 91; horses, 82, 100;
quarry remains, 32

Miohippus (mf'6-hip'us), 82

Mississippi River: delta fossils, 24;
flood deposits, 25

Moeris, Lake, 86

Moeritherium (mar"i-the'ri-um) : de-
scribed, 86, 88; place in elephant
phylogeny, 41, 91

Molluscs : Devonian, 52 ; Ordovician,
50

Mongolia: archaic mammals, 74;
dinosaurs, 63; dune dwellers, 16;
paleontological importance, 38

Mongolian kiang, 84

Monoclonius (mon"6-kl6'ni-us), 64*

Moropus (mo-rop'us), 32*, 34

Morrison fossil beds, 20, 35

Mosasaurs (mo'sa-sors") : fossil re-
mains, 25; habits, 65

Mount St. Stephen : carbon fossils, 34;
significance of discoveries on, 45

Mount Wapta, 34

Mousterian man, 96

Musk ox, 101

Mustangs, 84

Narwhal tusk, 38

Neanderthal (na-an'der-tal") man :
description, 96* ; Dune dwellers simi-
lar to, 15

Nebraska : Agate Spring Quarry, 31 ;
proboscideans in, 89

New Mexico horse fossils, 82

Newark System, 20

Nile delta fossils, 24

Niobrara (m"6-brar'a) formation, 25

Nothrotherium (n6th"r6-the'ri-um) :
see^ Sloths

Nubian ass, 84

Numbers of fossils, 17

Ohio fossil deposits, 10

Oil: fossils, an index to, 103; means of
fossilization, 6; source in ancient
organic matter, 104

Okapi (6-ka'pe), 99

Old Red Sandstone fossil deposits, 51

Oligocene (ol'i-go-sen") period : fossil
horses, 82; pine trees, 8

Ontogeny (on-toj'e-ni), 42

Ordovician (6r"d6-vish'an) period, 49

Orohippus (6r"6-hip'us), 82

Osborn, Henry Fairfield (1857- ),
American paleontologist : on dino-
saurs, 37 ; on racial extinction, 102

Ostracoderms (os'tra-ko-durm"), 52

Ouse (ooz) River : fossil deposits, 93,
95

Palaeoscincus (pa"le-6-skink'us) : ap-
pearance, 62; herbivorous nature,
64

Paleomastodon (pa"le-6-mas't6-don) ,
86, 96

Paleozoic (pa"le-6-zo'ik) era, 45

Palestine human fossils, 96

Parahippus (par"a-hip'us), 82

Passenger pigeon, 99

Peat swamp fossil deposits, 26

Peking man, 95

Pennsylvania fossil deposits, 13

Permian (pur'mi-an) period, 55

Petrification, 8

Phenacodus primaevus (fen-ak'6-dus
prl-me'vus) : appearance, 75* ; dis-
covery of, 74

Phylogeny (fi-16j'e-ni) : of horses, 81 ;
of the proboscideans, 87; proof of
evolution, 43

Piltdown man, 95*

Pithecanthropus erectus (pith"e-kan-
thro'pus e-rekt'us), 94*

Plants: forerunners of animals, 50;
modernized during Cretaceous pe-
riod, 72; preserved in amber, 8

Pleistocene (plis'to-sen) period :
asphalt beds, 27; fossil horses, 83;
fossil ground sloths, 7; fossil pro-
boscideans, 89, 90; glaciation, 83;
peat swamps, 26

Plesiosaurs (ple'si-6-sor") : fossil re-
mains, 25; habits, 65

INDEX

113

Plesippus (ple"zip'us), 83, 100

Pliocene (pli'6-sen) period: horse fos-
sils, 83; proboscidean fossils, 89, 91

Pliohippus (pli"6-hip'us), 83, 100

Po delta shells, 24

Polyps, 49

Pompeii natural molds, 11

Prjevalsky (psh-val'ski) horse, 84

Proboscidea (pro"b6-sid'e-a) : evolu-
tion, 85 ; phylogeny, 87*

Proterozoic (prot"er-6-zo'ik) era : evi-
dence of life lacking, 45; rock trails
of, 13

Protohippus (pr6"to-hip'us), 83

Protozoa (pr6"to-z6'a) : shells of, 16,
18; utilitarian value of fossils, 103

Pseudomorph (su'do-morf), 9

Pteranodon (te-ran'6-don) : appear-
ance, 67* ; flying ability, 25, 66

Pterodactyls (ter"6-dak'tils) : charac-
teristics, 66; fossil remains, 25, 29

Pterosaurs (ter'6-sor) : see Ptero-
dactyls

Pyramid of Cheops, 18

Quicksand fossil deposits, 26

Racial extinction, 99

Radiolaria (ra"di-6-la'rT-a) : appear-
ance, 23*; deep-sea deposits, 22

Rancho la Brea, Calif.: asphalt bed
fossils, 26*, 27

Reptiles: as the ancestors of modern
mammals, 70; classification, 57;
effect of climate on, 101 ; extinction
of the great, 71 ; first, 54 ; flying, 25,
29, 66; marine, 25; Mesozoic, 56, 65;
sec also Dinosaurs

Rhamphorhynchus (ram"f6-rin'kus) :
appearance, 29, 67* ; flying ability,
66

Rhinoceros: small twin-horned, 31*,
32; woolly, 5, 6

Rhinoceros tichorhinus, 5, 6

Rhodesian man, 97*

Rhone delta shells, 24

River bar fossil deposits, 24

Roaches, 55, 56

Rotti (rot'te) Island fossil deposits,
22

Sabre-tooth tigers, 27, 28*

Salamanders, 38

Samland amber, 8

Scorpions : become land creatures, 51*,
52 ; trilobites ancestral to, 49

Sea cows: common ancestry with pro-
boscideans, 91 ; extinction, 100

Sea-cucumbers, 35

Sea-lilies, 53*

Sea-urchins, 53

Sharks: dominant, 53; evolution, 52;
physiology, 10, 22, 23

Shellfish, 52

Shetland ponies, 102

Siberian mammoths, 5

Sigillaria (sij"i-la'n-a), 37

Silurian (si-lu'ri-an) period, 50

Sinanthropus pekinensis (sm-an'-
thro-pus pe"kin-en'sis), 95

Sloths, Ground: description of, 7*;
asphalt bed fossils, 27; coprolite as-
sociated with, 15

Smilodon (smi'ld-don), 27, 28*

Snails, 37

Solnhofen, Bavaria : fossil deposits, 28,
67

Somali ass, 84

South Joggins, Nova Scotia, 37

Southern mammoth, 90

Spiders: amber-preserved, 8; trilo-
bites ancestral to, 49

Sponges : Cambrian period, 45 ; lime-
stone reef fossils, 28

Spy, Belgium, 96

Squid, 29

Stegocephalians (steg"6-se'-fa'li-ans),
41, 54, 55*

Stegodonts (steg'6-donts), 89

Stegosaurus (steg"6-so'rus) : gro-
tesqueness, 37, 59* ; extinction, 62

Stenomylus (sten"6-rm'lus), 27, 32, 33*

Stratigraphical (strat"i-graf'i-kal) ge-
ology, 20

Struthiomimus (stroo"thi-6-mim'us),
64, 65*

Styracosaurus (sti"rak-6-so'rus), 64

Swine, Giant, 32*

Tertiary (tur'shi-a-ri) era, 23

Tetrabelodon (tet"ra-bel'6-d6n), 88

Thinopus antiquus (thm'6-pus an-ti'-
kwus), 13*

Thousand-legs, 52

Tigers, Sabre-tooth, 27, 28*

Timor (te-mor') Island, 22, 23

Tolmachoff, I. V. (1872- ), Ameri-
can scientist, 6

Trachodon (tra'ko-don) : herbivorous
nature, 64; skull modifications, 62;
swimming ability, 60

Transmutation, 100

Trees, Fossil, 37

Triassic (trl-as'ik) period, 13, 20, 57

Triceratops (trl-ser'a-tops) : appear-
ance, 63*; herbivorous nature, 64

Trilobites (trf 16-bits) : ancestral role,
49 ; Cambrian, 35, 45, 48* ; Devonian,
52; Ordovician, 50; trails, 13; extinc-
tion, 41, 56

Trilophodon (tri-lofo-don), 88

Trinidad fossil deposits, 22

Turtles : fossil remains, 24, 25, 29, 37 ;
habits, 65

114

FOSSILS

Tyrannosaurus (ti-ran"6-so'rus) : ap-
pearance, 65*; nature, 64

Uinta Lake deposits, 25, 76

Verona amphitheater fossils, 1

Vertebrates: evolution, 13*, 14, 51, 54;
warm-blooded, 56

Vinci (ven'che), Leonardo da (1452-
1519), Italian artist, architect, and
engineer, 1, 2

Vultures, 27

Walcott, Charles Doolittle (1850-1927),
American geologist, 34

Whales : size of modern, 59 ; slaughter
of, 100

Wolves: asphalt bed fossils, 27; ex-
tinct in England, 99

Woolly mammoth, 87, 90

Woolly rhinoceros : range of, 5 ; speci-
mens rare, 6

Worms : Cambrian, 35, 45 ; early con-
quer the land, 52; fossil history of,
13, 15*, 16

Wyoming : dinosaur 'beds, 35 ; mam-
malian remains, 71, 74

Zambezi delta fossil deposits, 24

a as in day

senate

add

care

far

last

KEY TO PRONUNCIATION

e as in mete

I as in time

e " " event

t "

idea

e " " end

i "

ill

e " " term

i "

' firm

g = j (gentile)

6 "

old

g as in get

6 " ' obey

o as in not
6 " " lord

u
u
u
u

use
unite
us
turn

Internet Archive Audio

Featured

Top

Images

Featured

Top

Software

Featured

Top

Books

Featured

Top

Video

Featured

Top

Mobile Apps

Browser Extensions

Archive-It Subscription

Save Page Now

Full text of "Fossils What They Tell Us Of Plants And Animals Of The Past"

See other formats