THE PLEISTOCENE OF NORTH AMERICA AND ITS VERTEBRATED ANIMALS FROM THE
STATES EAST OF THE MISSISSIPPI RIVER AND FROM THE CANADIAN PROVINCES
EAST OF LONGITUDE 95°.
BY
OLIVER P. HAY
_Associate of the Carnegie Institution of Washington_
[Illustration]
PUBLISHED BY THE CARNEGIE INSTITUTION OF WASHINGTON, FEBRUARY, 1923
CARNEGIE INSTITUTION OF WASHINGTON
PUBLICATION NO. 322
TECHNICAL PRESS
WASHINGTON, D. C.
------------------------------------------------------------------------
CONTENTS
PAGE
Preface VII–VIII
Conclusions regarding the divisions of the Pleistocene 1–15
Limits of the Pleistocene 1
The Blanco Pliocene 1
Divisions of the Pleistocene 2
Elevation of Continent 3
Connections of North America with South America and Asia 3
Sources of vertebrates 4
Richness of Pleistocene life 4
Evolution during the Pleistocene 5
Extinction of species 6
The earliest Pleistocene, the Nebraskan 7
The Aftonian interglacial 10
The Yarmouth interglacial 12
The Illinois glacial 12
The Sangamon interglacial 12
The Peorian interglacial 13
The Wisconsin and the Wabash beds 13
Coastal Plain terraces 13
Conspectus of Geology and Vertebrate Palæontology of the
Pleistocene 14–15
Finds of Pleistocene cetaceans in eastern North America 17–20
Ontario 17
Quebec 18
Vermont 19
New Brunswick 19
North Carolina 20
South Carolina 20
Florida 20
Finds of Pleistocene _Pinnipedia_ in eastern North America 21–30
Grinnell Land 21
Nova Scotia 21
New Brunswick 21
Quebec 21
Ontario 23
Maine 23
New Hampshire 25
Massachusetts 25
New Jersey 26
Virginia 28
North Carolina 29
South Carolina 29
Finds of Pleistocene _Xenarthra_ in eastern North America 31–44
New Jersey 31
Pennsylvania 31
Ohio 31
Indiana 32
Illinois 33
Virginia 34
West Virginia 34
South Carolina 35
Georgia 36
Florida 37
Alabama 40
Mississippi 40
Tennessee 41
Kentucky 43
Finds of mastodons in eastern North America 45–128
Ontario 45
Cape Breton Island 46
Massachusetts 47
Connecticut 47
New York 48
New Jersey 63
Pennsylvania 68
Ohio 70
Michigan 80
Indiana 88
Illinois 100
Wisconsin 110
Maryland 112
Virginia 113
West Virginia 115
North Carolina 115
South Carolina 118
Georgia 120
Florida 121
Alabama 124
Mississippi 124
Tennessee 127
Kentucky 128
Finds of _Elephas primigenius_ in eastern North America 130–146
Ontario 130
New York 131
New Jersey 132
Pennsylvania 133
Ohio 134
Michigan 137
Indiana 138
Illinois 140
Wisconsin 143
Maryland 144
Virginia 145
North Carolina 145
Florida 145
Tennessee 146
Kentucky 146
Finds of _Elephas columbi_ in eastern North America 147–161
Ontario 147
Vermont 148
New York 149
New Jersey 149
Pennsylvania 150
Ohio 150
Michigan 151
Indiana 151
Illinois 152
Maryland 154
North Carolina 155
South Carolina 155
Georgia 157
Florida 157
Kentucky 160
Finds of _Elephas imperator_ in eastern North America 162–164
South Carolina 162
Florida 162
Alabama 164
Finds of _Elephas_ sp. indet. in eastern North America 166–182
Ungava 166
Ontario 166
Vermont 167
New York 167
Pennsylvania 168
Ohio 168
Michigan 171
Indiana 171
Illinois 175
Wisconsin 178
Maryland and District of Columbia 178
Virginia 178
West Virginia 179
North Carolina 179
Florida 179
Mississippi 180
Tennessee 181
Kentucky 181
Finds of _Equidæ_ in eastern North America 183–202
Massachusetts 183
New York 183
New Jersey 184
Pennsylvania 184
Ohio 185
Indiana 186
Illinois 187
Maryland and District of Columbia 188
Virginia 189
West Virginia 190
North Carolina 190
South Carolina 191
Georgia 193
Florida 194
Alabama 200
Mississippi 200
Tennessee 201
Kentucky 202
Finds of tapirs in eastern North America 203–210
Pennsylvania 203
Ohio 203
Indiana 203
Maryland 204
Virginia 204
South Carolina 204
Georgia 206
Florida 206
Mississippi 208
Tennessee 209
Kentucky 209
Rhinoceroses in Florida 211
Finds of peccaries in eastern North America 212–223
New York 212
New Jersey 213
Pennsylvania 213
Ohio 214
Michigan 215
Indiana 216
Illinois 218
Wisconsin 219
Maryland 220
Virginia 221
West Virginia 221
South Carolina 221
Florida 222
Tennessee 222
Kentucky 223
Finds of camels in eastern North America 224–225
Pennsylvania 224
Florida 224
Tennessee 225
Finds of _Odocoileus_ in eastern North America 226–234
Ontario 226
New York 226
New Jersey 226
Pennsylvania 227
Ohio 227
Michigan 227
Indiana 228
Illinois 229
Wisconsin 230
Maryland 230
Virginia 231
West Virginia 231
North Carolina 231
South Carolina 231
Florida 232
Mississippi 233
Tennessee 234
Kentucky 234
Finds of _Cervus canadensis_ in eastern North America 235–243
Ontario 235
Vermont 235
New York 235
New Jersey 237
Pennsylvania 237
Michigan 237
Indiana 238
Illinois 239
Wisconsin 240
Maryland 242
North Carolina 242
South Carolina 242
Georgia 243
Florida 243
Tennessee 243
Kentucky 243
Finds of _Rangifer_ in the Pleistocene of eastern North
America 244–247
Grinnell Land 244
Ontario 244
Vermont 244
Connecticut 244
New York 245
New Jersey 245
Pennsylvania 246
Illinois 246
Wisconsin 247
Kentucky 247
Finds of musk-oxen in eastern North America 248–255
Grinnell Land 248
New Jersey 248
Pennsylvania 248
Ohio 249
Michigan 250
Indiana 251
Illinois 253
West Virginia 254
Mississippi 254
Kentucky 255
Finds of extinct bisons in eastern North America 256–265
Ontario 256
Pennsylvania 256
Ohio 257
Indiana 257
Illinois 259
Wisconsin 259
Maryland 259
Virginia 259
South Carolina 260
Georgia 261
Florida 262
Alabama 264
Mississippi 264
Kentucky 265
Finds of _Bison bison_ in eastern North America 266–271
Ontario 266
Massachusetts 266
New York 266
New Jersey 267
Pennsylvania 267
Indiana 268
Illinois 268
Wisconsin 270
Kentucky 270
Finds of _Castoroides_ in eastern United States 272–280
New York 272
Pennsylvania 272
Ohio 273
Michigan 275
Indiana 276
Illinois 278
South Carolina 279
Georgia 280
Mississippi 280
Tennessee 280
Pleistocene Geology of eastern North America and its fossil
vertebrates 281–406
Ontario 281
Quebec 288
New Brunswick, Nova Scotia, Cape Breton Island 289
New England 290
New York 294
New Jersey 299
Pennsylvania 306
Ohio 324
Michigan 330
Indiana 331
Illinois 334
Wisconsin 340
Maryland and District of Columbia 344
Virginia 351
West Virginia 354
North Carolina 355
South Carolina 361
Georgia 368
Florida 372
Alabama 384
Mississippi 385
Tennessee 393
Kentucky 400
ILLUSTRATIONS
PLATES.
MAP 1. Pleistocene cetaceans in eastern North America.
2. Pleistocene _Pinnipedia_ in eastern North America.
3. Pleistocene _Xenarthra_ in eastern North America.
4. Pleistocene _Xenarthra_ in Florida.
5. Pleistocene mastodons in eastern North America.
6. Eastern New York, western Massachusetts, and Connecticut,
showing relation of mastodon localities to areas of
sea-level in Late Wisconsin.
6A. Pleistocene mastodons in New Jersey.
7. Pleistocene mastodons in Ohio.
8. Pleistocene mastodons in Michigan.
9. Pleistocene mastodons in Indiana.
10. Pleistocene mastodons in Florida.
11. _Elephas primigenius_ in eastern North America.
12. _Elephas columbi_ in eastern North America.
13. _Elephas columbi_ in Florida.
14. _Elephas imperator_ in southeastern United States.
15. _Elephas imperator_ in Florida.
16. _Elephas_ sp. indet. in eastern North America.
17. Pleistocene horses in eastern North America.
18. Pleistocene horses in Florida.
19. Pleistocene tapirs in eastern North America.
20. Pleistocene peccaries in eastern North America.
21. Pleistocene camels in eastern North America.
22. Pleistocene species of _Odocoileus_ in eastern North
America.
23. _Cervus canadensis_ in Pleistocene of eastern North
America.
24. _Rangifer_ in Pleistocene of eastern North America.
25. Pleistocene musk-oxen in eastern North America.
26. Extinct bisons in Pleistocene of eastern North America.
27. _Bison bison_ in Pleistocene of eastern North America.
28. _Castoroides_ in eastern North America.
29. _Castoroides_ in Ohio.
30. _Castoroides_ in Indiana.
31. Areas in New York, Connecticut, Massachusetts, and Vermont
occupied by water at sea-level in Late Wisconsin stage.
32. Isobases of Late Glacial uplift.
33. J. W. Spencer’s view of preglacial drainage of the region
of the Great Lakes.
34. Wisconsin glacier in New York, lakes Newberry and Maumee,
and localities of mastodons.
35. Glacial map of Ohio.
36. Distribution of Pleistocene mammals in Ohio.
37. Glacial map of Indiana.
38. Glacial map of Illinois. Shows also localities of
Pleistocene vertebrates.
39. Coastal plain of North Carolina, with localities of
Pleistocene animals and plants.
40. Sketch map of Skidaway Island, near Savannah, Georgia.
41. Bigbone Lick and vicinity.
TEXT-FIGURES.
FIG. 1. Geological section of Twin Creek, near Beecher, Will Co.,
Illinois 108
2. Section across gully at Whitehall, Wisconsin 242
3. Region about Toronto, Ontario 282
4. Eastern Ontario, showing limit of marine and fresh-water
beaches 286
5. South shore-line of the Champlain sea 287
6. Preglacial drainage of the Upper Ohio 293
7. Geologic section of Fish House beds at Camden, New Jersey 302
8. Vicinity of Trenton, New Jersey, showing distribution of
the Trenton gravels 305
9. Geologic sections at Trenton, New Jersey 305
10. Northern Pennsylvania, showing glaciated areas 309
11. Section of Port Kennedy bone cave at time of first
exploration, 1871 318
12. Section of Port Kennedy bone cave at time of last
exploration, 1896 318
13. Metatarsal of _Ovis_ sp. indet., from Kendall Co., Illinois 338
14. Relation of the driftless area to the surrounding glaciated
areas 342
15. Diagram showing the supposed terraces of the Maryland
coastal plain 345
16. Section across Potomac River near Big Pool, Maryland,
showing gravel-covered terraces 347
17. Generalized section across Allegheny Valley at Parkers
Landing, W. Va. 349
18. Tooth of _Hydrochoerus pinckneyi_ 365
19. Jaw and tooth of a wolf from Charleston, South Carolina 366
20. Coastal plain of Georgia 369
21. Geologic section from north to south through the phosphate
deposits of Florida 377
22. Geological map of Mississippi embayment 388
23. County map of Tennessee, to show where Pleistocene fossils
have been found 395
24. Vertical section of Bigbone Cave, Elroy, Van Buren Co.,
Tennessee 398
25. Section on bank of Tennessee River at Nashville 400
PREFACE.
The writer has been engaged for several years on an investigation of the
Pleistocene geology of North America and of the Vertebrata which have
been discovered in the deposits of this epoch. It had been his
expectation to publish the results of all his studies at the same date.
However, on consultation with Dr. John C. Merriam, it was agreed that it
would be better to publish immediately that part which pertains to the
region lying east of the Mississippi River and, as to the country
further north, that east of longitude 95°.
At the outset the writer was convinced that, before just conclusions
could be reached, it was necessary to know what fossil materials had
been collected and under what geological and geographical conditions. He
therefore made as thorough a search as possible of the literature for
reports of discoveries of fossil vertebrates. Also, when in scientific
journals or in newspapers the finding of fossils was recorded, recourse
was had to correspondence, thus securing much exact information as to
locality, kind of matrix, depth, and other important data. Often
photographs have been obtained and even the materials themselves. The
writer has also visited many museums and colleges throughout the country
and examined their collections. Even in the smaller institutions, where
perhaps only a few objects have been secured and preserved, some of
these have furnished important information. Regret may be expressed that
in the larger museums and colleges, as well as the smaller ones, too
often there have been preserved only meager or no records regarding the
history of what would otherwise be valuable specimens.
In order to show the geographical distribution of the most important
species that occur in considerable numbers, a series of maps has been
prepared, pertaining to the following:
Whales and porpoises.
Seals and walruses.
The edentates.
Elephas primigenius.
E. columbi.
E. imperator.
E. species undetermined.
Mastodons, mostly Mammut.
Horses, mostly Equus.
Tapirs.
Peccaries.
Camels.
Odocoileus.
Cervus.
Rangifer.
Musk-oxen.
Bisons, extinct.
Bison bison.
Giant beavers.
Where the map of a State has become too crowded with numerals, a special
map of that State for that species or genus has been prepared. There are
maps of the edentates in Florida; mastodons of Indiana, of New York, of
Ohio, of Michigan, of Florida; _Elephas columbi_ in Florida; _Elephas
imperator_ in Florida; horses in Florida.
Other maps and figures for illustration of the Pleistocene geology will
be found in their proper places.
The first part of the present volume is occupied by a consideration of
the specimens recorded on the maps. Such information is noted as could
be secured, often satisfactory, little enough sometimes; but it has been
found that one can not foresee what important information a given fossil
may furnish. At least, the presence of the fossil at a locality
indicates the existence there of Pleistocene deposits of some kind. In
cases where other species have been associated with the one mapped and
described, these are noted.
When the consideration of these mapped species and genera is completed,
the Pleistocene geology of the various States and provinces is taken up,
so far as it is related to the vertebrate palæontology. This involved an
examination of much of the literature of the Glacial period; and here
one soon finds himself in face of huge tomes and endless articles and
detailed maps. Only somewhat less in amount is the literature of the
States beyond the glaciated area. The opportunity to misunderstand and
to commit errors is unlimited, and the writer can only hope for lenient
criticism.
An attempt has been made in the case of all vertebrate fossils to
determine their geological relations and to derive some general
conclusions regarding the history of our Pleistocene vertebrates and
their relation to the divisions of the Pleistocene epoch. The
conclusions reached are embodied in the immediately succeeding pages.
Not much attention has been given to the fossil invertebrates and
plants. It is evident that neither the mollusks nor the plants have
undergone any considerable change during Pleistocene times and are
therefore not available as indicators of geological stages, though often
useful for determining local climatic conditions. Their value can be
better utilized by the palæomalacologists and palæobotanists.
To the officers of museums and colleges and to the private individuals
who have so freely offered the use of their materials and in other ways
aided the writer, he takes pleasure in expressing his sincere thanks.
Most of all, however, he is indebted to the Carnegie Institution of
Washington for the generous support extended during the years of this
investigation.
JUNE 1, 1922.
OLIVER P. HAY.
THE PLEISTOCENE OF NORTH AMERICA AND ITS VERTEBRATED ANIMALS.
CONCLUSIONS REGARDING THE DIVISIONS OF THE PLEISTOCENE.
I. LIMITS OF THE PLEISTOCENE.
The Pleistocene is regarded as being equivalent to what is known as the
Glacial period. It began with the deployment of the ice-sheets which,
proceeding from their centers of accumulation in British America, laid
down in the East the Jerseyan drift and in the West the Nebraskan. The
more the Glacial period is studied the more one becomes impressed with
the significance of its physical effects on the northern hemisphere and
with its influence on the vertebrate life. Doubtless its effects on the
world in general are only beginning to be comprehended. The writer knows
of no other phenomena, geological or biological, which so well
characterize the Pleistocene period as do those comprehended under the
term Glacial. They constitute the key to the determination of the
subdivisions of the epoch and of their succession and to the history of
the vertebrates which during this time occupied the continent.
II. THE BLANCO PLIOCENE.
The Blanco is held to belong to the upper, or to the uppermost,
Pliocene. It is at present assigned to the Middle Pliocene (Osborn,
Bull. U. S. Geol. Surv. No. 361, p. 81; Matthew, ibid., p. 120). Until
recently the oldest known Pleistocene vertebrates appeared to be
represented by the collections which long ago were made at Fossil Lake,
Oregon, and at Grayson (Hay Springs), Nebraska. These assemblages had
formerly been referred to the Pliocene, and the belief that they belong
there is not yet wholly without supporters. It seemed, therefore, proper
to retire the Blanco somewhat. The discovery that the Fossil Lake and
Grayson faunas were represented in the Aftonian deposits of Iowa, and
belonged probably to the first interglacial stage, reveals the fact that
the geological interval between the Blanco and the Aftonian is at least
partly filled by the first glacial stage, the Nebraskan. Naturally, it
is to be expected that the breach between the earlier and the later
faunas will be occupied, in part at least, by the vertebrates of the
Nebraskan. What these are is not yet well determined; but the writer
believes that as the Blanco and its equivalent and closely related
formations and faunas become better known, they will be attracted close
to the Pleistocene.
Aside from the facts just mentioned, the Blanco fauna seems to the
writer to be more closely related to the Aftonian than has been
supposed. The genera which occur in the Blanco are the following:
Megalonyx.
Mylodon.
Glyptotherium.
Hipparion.
Pliohippus.
Protohippus.
Platygonus.
Pliauchenia.
Anancus.
Gomphotherium.
Stegomastodon.
Felis.
Amphicyon?
Borophagus.
Canimartes.
Of these, _Megalonyx_, _Mylodon_, _Hipparion_, _Platygonus_, _Anancus_,
_Gomphotherium?_, _Stegomastodon_, and _Felis_ are known from the first
interglacial stage. _Anancus_ includes mastodons with short, tuskless
lower jaws and trefoiled molars. _Gomphotherium_, having long lower jaws
with tusks, upper tusks with enamel band, and with trefoiled molars, may
be represented by some of the early Pleistocene species. The same
species of _Stegomastodon_ appears to be present in the Blanco as in the
Pleistocene, _S. mirificus_. The edentate _Glyptotherium_ is not far
removed from _Glyptodon_ of the early Pleistocene. The Blanco genera of
horses are so close to _Equus_ that Cope regarded them as belonging to
this genus.
The matter may be looked at from another point of view. If _Mylodon_,
_Megalonyx_, and _Glyptotherium_ are referred to the Middle Pliocene, we
shall probably have them recorded as living in Texas before they existed
in South America. It is true that Santiago Roth (Neues Jahrb., Min.
Beil., Bd., vol. XXVI, table opposite p. 144) states that _Glyptodon_
occurs in the Lower Pampas beds, and these he refers to the Upper
Miocene; but the writer believes that Wilckens (Neues Jahrb, Min. Beil.,
Bd., vol. XXI, p. 193) is more nearly correct in placing them in the
Pliocene. While the opinion may be correct that, when no obstacles
intervene, the time required for mammals to spread over even a continent
constitutes but a small part of a geological age, yet in making their
way from South America, especially from Argentina, along the narrow
bridge that appears to have been offered them, probably over mountain
ranges, and across rivers and gorges, and in the face of the competing
fauna advancing from the north, some of which were wolves and
saber-tooth tigers, the slowly plodding and inoffensive edentates would
have encountered too many hindrances to be able to make the journey in a
short time.
The writer, therefore, ventures to range the Blanco immediately below
the Pleistocene. On about the same level may be placed the
Tulare-Etchegoin and the Thousand Creek formations of Merriam (Bull.
Dept. Geol. Univ. Calif., vol. X, pp. 425, 429).
III. THE HISTORICAL DIVISIONS OF THE PLEISTOCENE.
The writer accepts the divisions of the Pleistocene which the geologists
appear to have established. Formerly it was believed that North America
had been subjected to a single glacial epoch; now it seems to be proved
that there have occurred five such glacial epochs, or stages, and that
there have intervened four interglacial stages of mild climate. The
interglacial stages are italicized. The Nebraskan stage is the earliest,
the Wisconsin the latest: Wisconsin, _Peorian_, Iowan, _Sangamon_,
Illinoian, _Yarmouth_, Kansan, _Aftonian_, Nebraskan.
The characteristics of the various stages will be briefly discussed. The
stages are not equally well understood and at present do not seem to be
of equal importance in their relation to vertebrate paleontology.
IV. ELEVATIONS OF THE CONTINENT IMMEDIATELY PRECEDING OR ACCOMPANYING
THE OPENING OF THE PLEISTOCENE.
In pursuing the study of the Pleistocene, one soon realizes that this
period was one of great geological activity. Ranges of mountains, if not
begun anew, were at least raised to greater altitudes. The Cascade Range
appears to have begun to rear its head at the beginning of the epoch, or
even a little later. Here and there the crust of the earth was ruptured
and great sheets of lava were poured out over the land. Ice caps
repeatedly accumulated over large areas in North America and Europe, and
in their movements southward transported vast amounts of earthy débris
and turned the courses of great streams. Apparently at times the
rainfall was greatly increased. The rivers, quickened by greater slope
and the increased volume of water, cut their channels deeper and in the
mountains excavated profound gorges. Through elevation of the land North
America was, late in the Pliocene or early in the Pleistocene, put into
easy communication with Asia and South America, so that vertebrated
animals passed freely to and fro. A part of these activities probably
belonged to the latter part of the Pliocene. In the more elevated
regions of the eastern United States, through the chemical, rupturing,
and transporting properties of water, rocks were dissolved and their
disintegrated materials produced what has been designated the Lafayette
formation; but it is possible that this belongs to the early
Pleistocene.
V. CONNECTIONS WITH ASIA AND SOUTH AMERICA.
Mention has just been made of a land connection with Asia at some time
about the beginning of the Pleistocene. The evidence for this may be
called circumstantial rather than direct. The geological evidence has
not been developed. If any deposits containing marine fossils had been
laid down along the Asiatic and Alaskan coasts during a time of
elevation, they would now be covered by the sea. Our evidence for the
connection is derived from the distribution of the vertebrate animals.
During the early Pleistocene our country was invaded by a host of
mammals whose home was originally in Asia. These included elephants,
bisons, elk, goats, bears, wolves, and foxes, besides many mammals of
smaller size. It is the presence in America of the smaller animals, many
genera of rodents of Asiatic origin, that shows that there must have
been a land connection. These could not have made their passage across
Bering Strait on the ice, as it might be imagined the larger animals
did.
The way between the two continents had more than once before been open,
but it was during the early Pleistocene that modern Asiatic genera
entered North America in great numbers. Exactly where the land bridge
between the two countries was situated is not certain; it may be that a
large part of the area now occupied by Bering Sea was then dry land.
Arldt (Entwicklung der Kontinente, plate 21) represents a connection
extending from the northern border of Alaska southward to include the
Aleutian Islands. Where narrowest, this bridge, as represented by the
author named, extended from latitude 60° to 70°, a distance of about 700
miles. In such case the cold currents from the Arctic Ocean would have
been prevented from entering the Pacific, while the Japan Current would
have warmed up the southern side of the bridge. The route was then open
on the north for the boreal animals of Asia to enter Alaska; while on
the south the genera inhabiting the more temperate part of eastern Asia
would have had free access to the American shore. Once on the continent,
the boreal mammals might have spread along the shores of the Arctic
Ocean and those of the temperate parts of Asia have made their way up
the Yukon Valley, or possibly along the Pacific coast, to the warmer
regions toward the south. We do not need to suppose that even during the
first glacial, or Nebraskan, stage the climate of that part of North
America was as inclement as now.
At the other end of our continent a train of events not wholly
dissimilar was in motion. Even in the latter part of the Pliocene some
South American edentates, such as _Megalonyx_, _Mylodon_, and
_Glyptotherium_, had reached Texas. Probably a little later the bridge
had become widened so that other edentates and a few genera of South
American hystricine rodents swarmed into our southern borders. At the
same time a host of carnivores, tapirs, horses, camels, peccaries, deer,
and cricetine and sciurine rodents made their way into South America. It
is now certain that the land bridge over which the interchange took
place did not include the West Indies. Possibly there yet remained along
the western coast of Central America some of the border, now submerged,
which Schuchert (Bull. Geol. Soc. Amer., vol. XX, plates 96 to 100)
represents as being present during the Tertiary.
VI. THE SOURCES OF THE VERTEBRATES OF THE PLEISTOCENE.
The Pleistocene vertebrate fauna of North America has been derived from
three sources. One component had descended from the animals which
occupied the continent during the late Tertiary, but even these were of
mixed derivation. A few appear to have filtered in from South America
during the Pliocene; others had come from Asia during Tertiary
invasions; but a large element was native to the country. As such may be
taken the camels, the peccaries, the three-toed horses, the prong-horn
antelope, the deer of the genus _Odocoileus_.
Upon a continent of vast extent and great fertility, possessing
unbounded variety of climate and habitat, all these animals were thrown
together to struggle for their existence. We must depend upon the
imagination to picture what the result would have been if nature had
pursued a course which might have been predicted. What the result in
reality was, we shall see.
VII. THE RICHNESS OF THE PLEISTOCENE VERTEBRATE LIFE.
It will be profitable to consider briefly the character of the
Pleistocene vertebrate fauna. The writer has compiled a list of the
species which have, so far as he knows, been collected and described up
to this time. There are in all 637 species; of these, 387 belong to the
mammals, 154 to the birds, 26 only to the reptiles, 7 to the amphibians,
56 to the bony fishes, and 7 to the group of sharks and rays. Certainly
these form only a part of the species which existed. At present there
are known in our existing fauna north of Mexico 693 species of mammals,
excluding the cetaceans—somewhat more than twice the number of known
Pleistocene species. It is, however, rather in the great variety of
forms that the Pleistocene excelled. Following Gerrit S. Miller’s Land
Mammals of North America, 1912, we find in our present fauna north of
Mexico 29 families; in the Pleistocene there are now known 37 families,
not including the cetaceans. In our existing mammalian fauna there are
recognized 111 genera; in the Pleistocene, with hardly half as many
species recorded, 138 genera are counted. In order to realize more
vividly the variety of Pleistocene forms, we have only to recall the
animals then present, now absent, namely, the great ground-sloths, the
glyptodons, the numerous species of horses, tapirs, numerous peccaries,
camels, the extinct relatives of the musk-oxen, extinct bisons,
elephants, mastodons of three or four genera, the giant beaver, and the
saber-tooth tigers. Among the birds, reptiles, batrachians, and fishes,
there were few striking forms, and these were mostly among the birds and
the tortoises.
The above account shows the great richness of the vertebrate life during
the Pleistocene; furthermore, this abundance evidently existed during
the early stages of the epoch. It constituted the materials on which
that combination of conditions which we call environment had to work
during Pleistocene times. The comparison shows that the result was an
impoverishment of the vertebrate fauna. Genera and families, even
orders, were wiped out of existence, and these included some of the
noblest animals that have graced the face of the earth, the elephants,
the mastodons, tapirs, many species of bison, horses, saber-tooth cats,
huge tigers, and gigantic wolves. The following nine or ten families
became either wholly extinct or continued to exist only in other more
hospitable lands: the Megatheriidæ, including several genera of
ground-sloths; the Hoplophoridæ or glyptodons; the Caviidæ, which
embraced one or more species of huge capybaras; the Elephantidæ, under
which are arranged three or four species of elephants and three genera
of mastodons; the Equidæ, represented by a dozen or more species of
horses; the Camelidæ, of which there were several Pleistocene species
and probably three or four genera; the Hyænidæ, of which there appears
to have been at least one genus, with one species; the Tapiridæ,
including three or four species; and probably the Rhinocerotidæ. Besides
these, the subfamily of Felidæ known as Machairodontinæ, embracing those
wonderful carnivores the saber-tooth tigers, was suppressed. The
Dasypodidæ, which included some armadillos 5 or 6 feet long, are now
represented by only one small species in Texas. Of the Tagassuidæ, to
which belonged several genera and stately species of peccaries, there
exists now in North America north of Mexico but one species, an animal
of only moderate size.
VIII. ON EVOLUTION DURING THE PLEISTOCENE.
We have seen that the Pleistocene fauna was very different from that
which existed when white men first entered the country; also that the
difference has in large part been due to the destruction of species,
genera, and families. We may now inquire whether or not the loss has
been to any considerable extent compensated by the development of new
forms. Many of our existing genera and species have been found in the
collections that represent the earliest Pleistocene known to us. The
writer believes it would be unsafe to say that any living species that
one might select may not hereafter be discovered in early Pleistocene
collections. It is probably true, however, that some of those small
changes by which we distinguish one species from another have been
produced. Some small but persistent differences might, for example, have
arisen in the teeth or in the form of the skull of a group of muskrats
which would justify us in regarding it as forming a new species. It is
extremely doubtful that any new genus of vertebrates has been developed
since the first interglacial stage. Matthew has concluded (Science, n.
s., vol. XL, pp. 232–235) that the evolution of the mammals during the
Pleistocene amounts to about one-tenth of that achieved during the
Pliocene. The present writer regards this as a liberal estimate.
This failure to evolve new genera and species is not necessarily to be
attributed to the shortness of the Pleistocene period; it may have been
due rather to the unfavorable conditions. In what direction could an
animal make progress when, after being subjected for some thousands of
years to one set of conditions, it was compelled for some other
thousands to endure just the opposite conditions? If life in front of a
glacier for some centuries led to the development of a coat of hair on
an elephant, that coat would probably disappear during the succeeding
interglacial stage, and in the end, if the elephant had not perished, he
would be where he began.
Too much stress must not, however, be placed on this suggestion. It may
yet be possible to show that nowhere in the world was any considerable
progress made by mammals during the Pleistocene, in the modification of
their forms and structure. On the other hand, it is also possible that
all over the world climatic conditions were at intervals unfavorably
affected by the development of the great glaciers and that all life was
retarded in its evolution. The writer believes, therefore, that it can
not be shown with certainty that new forms of living things, especially
vertebrates, were developed in North America during the Pleistocene. It
may be quite as difficult to prove that any genera or species of
importance entered from other lands after the first invasion. Under
these conditions there appears to be no means for determining successive
faunas other than through recording the time of the disappearance of
genera and species.
IX. DID THE EXTINCTION OF SPECIES TAKE PLACE MOSTLY AT THE END OF THE
PLEISTOCENE?
At the beginning of the Pleistocene there existed, as has been shown, an
abundant and highly varied mammalian fauna; at the close of the epoch
this fauna had become relatively impoverished. Did all those families
and genera and species, that in the end were missing, perish during or
after the last glacial stage, the Wisconsin? This opinion has been
expressed by some. The writer believes that this view is wholly
improbable.
A glacial sheet, stretched across the continent or a large part of it,
was not local in its effects; it was not a cap of ice merely concealing
a part of the land and covered possibly by forests and allowing
occupation by certain hardy animals, while beyond, up to its foot, the
country was pleasantly cool, wooded, and abounding with animated
creatures. In the Sierra Nevada Mountains of California (Lindgren, Folio
66, U. S. Geol. Surv.) and of Nevada (Knopf, Prof. Pap., U. S. Geol.
Surv., 110, pp. 92–105) and in the San Juan Mountains of Colorado
(Atwood and Mather, Jour. Geol., vol. XX, p. 385), at distances of
approximately 600 or 700 miles from the glacial front, there existed,
during more than one stage, extensive local glaciers. Along the Atlantic
coast during at least one glacial stage the walrus was driven as far
south as Charleston, South Carolina. One can hardly doubt that the whole
continent was chilled during each of the glacial stages.
To mammals, which for perhaps various reasons had been with difficulty
enduring the stress of existence, the glacial climates would give the
final stroke; perhaps to others the interglacial climates would have
been quite as fatal. We can not doubt that each glacial and each
interglacial stage swept away a few of the less hardy genera and
species. Nevertheless, several remarkable animals passed through the
vicissitudes of all the glacial and interglacial times and left their
bones in the deposits overlying the last, or Wisconsin, drift. Such are
two species of elephants, the American mastodon, the giant beaver, and
one or more species of peccaries. Why they succumbed at last is
difficult to say. Possibly the return of a fifth warm era proved too
much for their endurance.
A reason for believing that the genera and species missing from the
fauna found here when white men arrived, called sometimes the Columbian
fauna, were exterminated gradually and not at one epoch is that certain
ones are found in deposits overlying the earlier glacial drift-sheets,
but are not found in deposits on later drifts. Camels occur in Aftonian
beds overlying the Nebraskan drift, but have not been collected in later
interglacial deposits. Horses grow scarcer as the Pleistocene advances.
They are known from deposits overlying the Illinoian drift, but do not
appear after the Wisconsin.
X. THE STRATIGRAPHICAL AND TIME LIMITS OF THE EARLIEST PLEISTOCENE.
It is necessary to determine, if possible, where the boundary line shall
be drawn between the Pliocene and the Pleistocene. Room must be made for
the first interglacial, the Nebraskan, and its fauna. How long this
first glacial stage continued we do not know. Chamberlin and Salisbury
have indicated (Geology, vol. III, p. 420) that in a rough way the dates
from the present of the culmination of the various glacial stages,
except the Nebraskan, taken in order backward, may be represented by the
geometrical series 1, 2, 4, 8, 16. That is, if the Illinoian stage had
its culmination 150,000 years ago, that of the Kansan occurred 300,000
years ago; if the Nebraskan should fall in the same series, it
culminated 600,000 years ago; and it and the succeeding Aftonian
interglacial held sway as long as all the rest of the Pleistocene put
together. It would be rash to assert that this first glacial did last so
long; but we see the possibilities. In a personal communication
Professor Frank Leverett writes that he estimates that the Kansan
culmination took place at not less than 400,000 years ago and the
Nebraskan at 500,000. This, as the present writer estimates, would leave
for the Nebraskan itself somewhere near 40,000 or 50,000 years. Some
changes in the life of the Pleistocene must have been wrought during
those years.
The glacial deposits of the Nebraskan stage are not as well known as one
might wish. They appear to be in general overlain by the later drifts
and are observed mostly where streams have cut through both the
overlying drift and the Nebraskan. The old drift found in New Jersey is
thin and of no great extent. Moreover, we can hardly expect to find
fossil vertebrates in the drift itself. We must therefore depend on
studies of supposed Nebraskan fossils found mostly outside of the
glaciated area and make comparison of them with earlier and later
faunas. If we shall discover collections of Nebraskan vertebrate
animals, we may be sure that they will differ from those of the first
interglacial, the Aftonian. We may be pretty certain that they will
include autochthonous genera of the late Tertiary, which may be missing
from the Aftonian, together with at least a few genera from South
America and others from Asia.
Now, have any formations and included fossil vertebrates been found
which may be fitted into the Nebraskan interval?
In this stage the writer places the beds which Cope designated the Idaho
formation (Cope, Proc. Acad. Nat. Sci. Phil., 1883, p. 135). Since
Cope’s time several new species have been added to his list from this
formation. In 1917 (Bull. Dept. Geol. Univ. Calif., vol. X, p. 432), Dr.
J. C. Merriam published a list of the fossils, except fishes, which had
been secured up to that time. The list of species referred to the Idaho
formation is as follows:
Equus idahoensis.
E. excelsus?
Protohippus?
Rhinoceros, probably Aphelops (Teleoceras) fossiger.
Mastodon mirificus.
Cervus, possibly new. Smaller and more slender than C. canadensis.
Procamelus, size of P. major.
Tragocerus? horn-core of antelope.
Ischyrosmilus n. sp.
Morotherium leptonyx.
Castor, possibly n. sp.
Olor, size of O. paloregonus.
Graculus idahoensis.
In this collection the presence of horses of the genus _Equus_, of
_Cervus_, _Morotherium_, and _Castor_, is strongly suggestive of the
Pleistocene. The type of _Mastodon mirificus_ was found in Pleistocene
deposits of probably Aftonian age. Although rhinoceroses are supposed to
have become extinct before the end of the Pliocene, this supposition may
be an error. The list of Blanco vertebrates is a short one, and the
absence of a genus from it is not decisive. One drawing of a seine in
the sea-waters of Florida would furnish inadequate materials for
conclusions about the fish fauna of that coast.
The Thousand Creek fauna (Merriam, Bull. Dept. Geol. Univ. Calif., vol.
X, p. 429), which to the present writer appears of about the same age as
the Blanco, contains a species of _Teleoceras_. The genera _Protohippus_
and _Procamelus_ might be supposed to have continued their existence and
evolution until interrupted by an age of ice and by competitors from
Asia.
In 1917 (Bull. cit., vol. X, pp. 255–266) Merriam and Buwalda published
a short list of fossils which they had collected along the Columbia
River in Washington State. A horse was found which was referred to
_Equus_ or _Pliohippus_; also two camelids, one of which was thought to
be near _Pliauchenia_. Merriam concluded that the evidence on the whole
favored the Pleistocene. The list will fit into the Nebraskan without
difficulty.
In 1889 (Amer. Naturalist, vol. XXIII, p. 253), Professor E. D. Cope
published a list of fossil mammals collected in the “Oregon desert,”
apparently somewhere in the region of Silver Lake or Summer Lake. The
list is as follows:
Canis sp. indet.
Elephas or Mastodon.
Holomeniscus or Auchenia.
Aphelops sp. indet.
Hippotherium relictum.
Equus sp. indet.
Cope looked upon this collection as remarkable in that it showed the
presence of true horses and camels associated with a rhinoceros. He
concluded that the fossils belonged to his Idaho formation. Dr. W. D.
Matthew thought that the collection was a mixture of fossils from two
formations (Bull. Amer. Mus. Nat. Hist., vol. XVI, p. 321). It may,
however, have been made in Nebraskan deposits.
In 1921 (Proc. U. S. Nat. Mus., vol. LIX, pp. 617–638), the writer
described a collection of vertebrate remains from Anita, Coconino
County, Arizona. These remains were found in a cave in making
explorations for copper ore. The list follows:
Equus occidentalis.
E. giganteus?
Mylohyus? sp. indet.
Procamelus coconinensis.
P. longurio.
Antilocapra americana?
Marmota arizonæ.
Citellus tuitus.
Neotoma cinerea.
Lepus benjamini.
Brachylagus browni.
Taxidea robusta.
Canis nubilus?
C. latrans?
Chasmaporthetes ossifragus.
The writer believes that this assemblage of mammals must be referred to
the Pleistocene. It will be noted, however, that there are two species
of the genus _Procamelus_. These resemble so much two species, _P.
major_ and _P. minimus_, described by Leidy and Lucas (Trans. Wagner
Free Inst., vol. IV, pp. I-XIV, 15–61) from the Alachua clays of
Florida, that it seemed at first necessary to identify them as such. The
genus _Procamelus_ seems, therefore, to be brought definitely into the
early Pleistocene, probably the Nebraskan.
The collections made in the Alachua clays in Florida were obtained in
Alachua and Levy counties. On pages 195 and 375 will be found an account
of the geological conditions under which the fossils were found, and
lists of the species. The essential features are that such supposed
Miocene or Pliocene genera as _Gomphotherium_, _Procamelus_,
_Teleoceras_, and _Aphelops_ were found associated with the Pleistocene
genera _Odocoileus_, _Tapirus_, _Megatherium_, and _Equus_. This has
been explained on the theory that the clays are of Tertiary age and that
the Pleistocene species had become mingled with those of an earlier
time. At a number of places in Florida where phosphate rock has been
mined there have been secured similar associations of early camels,
rhinoceroses, horses (_Hipparion_, _Parahippus_) with genera belonging
undoubtedly to the Pleistocene. This has occurred so often that the
writer doubts the correctness of the explanation given. He ventures,
therefore, to include in the Pleistocene of the Nebraskan stage the
various deposits that have received the names Alachua clays, the
Dunnellon formation, and Bone Valley formation. The latter, called also
the land-pebble phosphates, is believed by Sellards to be
contemporaneous in age with the Dunnellon or hard phosphates, but to
have accumulated under different conditions. Both the Alachuan and the
Bone Valley formations were referred by Sellards to either the late
Miocene or the early Pliocene, with an evident preference for the
latter. It seems to have been the presence of the rhinoceroses that most
influenced him in his assignment of the deposits; but there were
naturally other considerations. He wrote:
The presence of rhinoceroses in the formation is believed to
establish definitely the fact that the beds can not be later than
the early Pliocene, since rhinoceroses in America apparently did not
survive beyond that time (Fla. Geol. Surv., vol. VII, p. 73).
According to Sellards the hard phosphate, belonging to the Alachua
(Dunnellon) formation (Fla. Geol. Surv., vol. V, p. 37) resulted from a
disintegration of underlying Upper Oligocene deposits and probably the
Vicksburg limestone. Through chemical action these rocks were partly
dissolved and the residual materials were mixed by local subsidence and
by action of streams and later modified by chemical changes.
The land-pebble phosphate of the Bone Valley formation had, Sellards
concluded (Fla. Geol. Surv., vol. VII, p. 55), resulted from underlying
phosphate marls of Upper Oligocene age. This occurred during a time of
general subsidence of sufficient extent to permit marine waters to reach
the area covered by the Bone Valley phosphates. The presence of
sea-water is indicated by the occurrence of bones of cetaceans.
With regard to the effects of streams and of the chemical action of the
water on the rocks, which contributed to the formation of the hard rock
phosphate and the production of sinks and caves, it may be remarked that
we know of no time when rocks were dissolved and caves formed to the
extent that they were during the Pleistocene.
As shown on page 15, various deposits of marine marls along the Atlantic
coast are referred by the writer to the Nebraskan. Among these marls are
the coquina rock found at St. Augustine and the marine marl underlying
the bed at Vero, which contained early Pleistocene vertebrate fossils.
These marls are known to extend well inland, being found at Kissimmee,
50 miles from the coast. In some places they are met with at depths of
70 feet (Sellards, Fla. Geol. Surv., vol. VIII, pp. 105–106). Marls of
probably the same age occur on the western coast of Florida (Dall, Bull.
84, U. S. Geol. Surv., p. 152). The writer believes that some of these
marls may yet be connected with the phosphate beds of the Bone Valley
formation.
A figure taken from Sellards (Geol. Surv. Fla., vol. VII, opp. p. 53)
may be found on page 377. This illustrates the relation of the Dunnellon
and Bone Valley formations to the underlying deposits.
XI. THE FIRST INTERGLACIAL, OR AFTONIAN, STAGE.
Mention has been made of collections of fossil vertebrates which long
ago were secured at Fossil Lake, Oregon, and of others along Niobrara
River, near Grayson, Nebraska. Lists of the species found at each
locality were given by Dr. W. D. Matthew in 1902 (Bull. Amer. Mus. Nat.
Hist., vol. XVI, pp. 317–320). These deposits and animals were regarded
by Cope and Marsh as belonging to the Pliocene, until G. K. Gilbert, in
his work on Lake Bonneville (Monogr. I, U. S. Geol. Surv., pp. 393–402)
showed that the Oregon fossils must belong to the Glacial epoch, but he
referred them to a late time in this epoch, that of the last glaciation.
It thus became quite impossible to determine the age of any collection
of fossil vertebrates.
In 1887 (Univ. Geol. Surv. Kansas vol. II, pp. 299–308), Williston
wrote:
Every fact furnished from Kansas seems to substantiate Cope’s
conclusion that the _Megalonyx_ fauna of the East and the _Equus_
fauna of the West were contemporaneous and that both occurred during
the period of depression; that is, during late Pleistocene time.