Part 12

From the great local abundance of their remains, it has been thought that the curious short-legged Pliocene rhinoceros, _Aphelops fossiger_, was killed off in the West by blizzards when the animals were gathered in their winter quarters, and other long-extinct animals, too, have been found under such conditions as to suggest a similar fate.

Among local catastrophes brought about by unusually prolonged cold may be cited the decimation of the fur-seal herds of the Pribilof Islands in 1834 and 1859, when the breeding seals were prevented from landing by the presence of ice-floes, and perished by thousands. Peculiar interest is attached to this case, because the restriction of the northern fur-seals to a few isolated, long undiscovered islands, is believed to have been brought about by their complete extermination in other localities by prehistoric man. Had these two seasons killed all the seals, it would have been a reversal of the customary extermination by man of a species reduced in numbers by nature.

In the case of large animals another element probably played a part. The larger the animal, the fewer young, as a rule, does it bring forth at a birth, the longer are the intervals between births, and the slower the growth of the young. The loss of two or three broods of sparrows or two or three litters of rabbits makes comparatively little difference, as the loss is soon supplied, but the death of the young of the larger and higher mammals is a more serious matter. A factor that has probably played an important rôle in the extinction of animals is the relation that exists between various animals, and the relations that also exist between animals and plants, so that the existence of one is dependent on that of another. Thus no group of living beings, plants or animals, can be affected without in some way affecting others, so that the injury or destruction of some plant may result in serious harm to some animal. Nearly everyone is familiar with the classic example given by Darwin of the effect of cats on the growth of red clover. This plant is fertilized by bumble bees only, and if the field mice, which destroy the nests of the bees, were not kept in check by cats, or other small carnivores, their increase would lessen the numbers of the bees and this in turn would cause a dearth of clover.

The yuccas present a still more wonderful example of the dependence of plants on animals, for their existence hangs on that of a small moth whose peculiar structure and habits bring about the fertilization of the flower. The two probably developed side by side until their present state of inter-dependence was reached, when the extinction of the one would probably bring about that of the other.

It is this inter-dependence of living things that makes the outcome of any direct interference with the natural order of things more or less problematical, and sometimes brings about results quite different from what were expected or intended.

The gamekeepers on the grouse moors of Scotland systematically killed off all birds of prey because they caught some of the grouse, but this is believed to have caused far more harm than good through permitting weak and sickly birds, that would otherwise have fallen a prey to hawks, to live and disseminate the grouse distemper.

The destruction of sheep by coyotes led the State of California to place a bounty on the heads of these animals, with the result that in eighteen months the State was called upon to pay out $187,485. As a result of the war on coyotes the animals on which they fed, notably the rabbits, increased so enormously that in turn a bounty was put on rabbits, the damage these animals caused the fruit-growers being greater than the losses among sheep-owners from the depredations of coyotes. And so, says Dr. Palmer, "In this remarkable case of legislation a large bounty was offered by a county in the interest of fruit-growers to counteract the effects of a State bounty expended mainly for the benefit of sheep-owners!"

Professor Shaler, in noting the sudden disappearance of such trees as the gums, magnolias, and tulip poplars from the Miocene flora of Europe has suggested that this may have been due to the attacks, for a series of years, of some insect enemy like the gipsy moth, and the theory is worth considering, although it must be looked upon as a possibility rather than a probability. Still, anyone familiar with the ravages of the gipsy moth in Massachusetts, where the insect was introduced by accident, can readily imagine what _might_ have been the effect of some sudden increase in the numbers of such a pest on the forests of the past. Trees might resist the attacks of enemies and the destruction of their leaves for two or three years, but would be destroyed by a few additional seasons of defoliation.

Ordinarily the abnormal increase of any insect is promptly followed by an increase in the number of its enemies; the pest is killed off, the destroyers die of starvation and nature's balance is struck. But if by some accident, such as two or three consecutive seasons of wet, drought, or cold, the natural increase of the enemies was checked, the balance of nature would be temporarily destroyed and serious harm done. That such accidents may occur is familiar to us by the damage wrought in Florida and other Southern States by the unwonted severity of the winters of 1893, 1895, and 1899.

If any group of forest trees was destroyed in the manner suggested by Professor Shaler, the effects would be felt by various plants and animals. In the first place, the insects that fed on these trees would be forced to seek another source of food and would be brought into a silent struggle with forms already in possession, while the destruction of one set of plants would be to the advantage of those with which they came into competition and to the disadvantage of vegetation that was protected by the shade. Finally, these changed conditions would react in various ways on the smaller birds and mammals, the general effect being, to use a well-worn simile, like that of casting a stone into a quiet pool and setting in motion ripples that sooner or later reach to every part of the margin.

It is scarcely necessary to warn the reader that for the most part this is purely conjectural, for from the nature of the case it is bound to be so. But it is one of the characteristics of educated man that he wishes to know the why and wherefore of everything, and is in a condition of mental unhappiness until he has at least formulated some theory which seems to harmonize with the visible facts. And from the few glimpses we get of the extinction of animals from natural causes we must formulate a theory to fit the continued extermination that has been taking place ever since living beings came into the world and were pitted against one another and against their surroundings in the silent and ceaseless struggle for existence.

THE END.

INDEX

_The asterisk denotes that the animal or object is figured on or opposite the page referred to._

Æpyornis, egg of, 145, 148,* 147, 157 eggs found in swamps, 148; found floating, 148 eggs used for bowls, 145 origin of fable of Roc, 144, 145

Alaskan Live Mammoth Story, 190-193, 197

Anomoepus tracks, 39

Apteryx egg, 147

Archæopteryx, description of, 77, 78 discovery of, 77 earliest known bird, 70 restoration, 89* specimens of, 70,* 88 wing, 72,* 73

Archelon, a great turtle, 54

Basilosaurus, 60 See also Zeuglodon

Beehler, L. W., 209, 213

Birds, always clad in feathers, 71, 127 earliest, 70

Birds, first intimation of, 76 rarity of fossil, 86, 87 related to reptiles, 92 wings of embryonic, 73 with teeth, 79, 88

Bison, European, 231

Books of reference, xix, 17, 32, 47, 69, 89, 110, 137, 158, 176, 197, 218

Breeding of large animals, 233

Brontornis, size of leg-bones, 149

Brontosaurus, size of bones, 96,* 97,* 109

Brooks, W. K., on Lingula, 229

Buffalo legend, 216

Buttons as vestigial structures, 202

Carcharodon auriculatus, 66 teeth, 66 megalodon, 65 estimated size, 66 teeth, 65, 67

Carson City footprints, 45

Casts, how formed, 10, 11

Cats and clover, 234

Cephalaspis, 24*

Ceratosaurus, habits, 106 restoration, 106* skull, 110*

Changes in Nature slow, 227

Cheirotherium, 43

Chlamydosaurus, 129

Claosaurus. See Thespesius

Climate, changes in western United States, 174

Clover and cats, 234

Cold, effects of, on animals, 230, 231, 233

Cold winters, 230

Collecting fossils, 17, 112-116

Color of large land animals, 134 of young animals, 136

Covering of extinct animals sometimes indicated, 131, 132

Coyotes, effect of their destruction on fruit, 236

Dall, W. H., theory as to extinction of mollusks, 227

Dinosaurs, bones of, 109, 110 brain of, 93 collections of, 109 compared to marsupials, 95 first discovered, 90 food required by, 98 hip-bones mistaken for shoulder-blade, 120 Professor Marsh's epitaph for, 222 range, 92 recognized as new order of reptiles, 91 related to ostrich and alligator, 91 size of, 95, 96, 98 tracks, ascribed to birds, 38

Dinotherium, 200

Diplodocus, estimated weight, 99 supposed habits, 99

Egg of Æpyornis, 147, 148; Apteryx, 147; Ostrich, 146; Moa, 148

Eggs, casts of, 87

Elephant, size, 180 size of tusks, 181, 182

Elephas ganesa, tusks, 196

Encrustations, 14

Extermination. See Extinction

Extinction, ascribed to great convulsions, 225 ascribed to primitive man, 188, 224 of Dinosaurs, 221 local, 225 by man, 224, 225 of Marine Reptiles, 222 often unaccountable, 222, 223 of Pliocene rhinoceros, 232 sometimes evolution, 221, 226 of Titanotheres, 222

Feathers, imprints of, 76, 132

Fishes, abundance of, 25 armored, 23, 24, 25, 28 collections of, 32 killed by cold, 230 killed by volcanoes, 231

Fish-crows, killed by cold, 231

Flesh does not petrify, 10

Flightless birds, absent from Tasmania, 155 present distribution, 154, 155 relation between flightlessness and size, 156

Folds and frills, 129

Footprints, collections of, 47 books on, 47 See also under Tracks

Fossil birds, rarity of, 86

Fossil man, 13

Fossilization a slow process, 10

Fossils, conditions under which they are formed, 5, 7 collecting, 112-116 definition of, 1 deformation of, 16 impressions, 2, 3 not necessarily petrifactions, 2 preparation of, 117-119 why they are not more common, 5, 15, 16

Fowls, muscles of, 81

Frill of Triceratops, 102

Fur-seals killed by ice-floes, 233

Gar pikes, destruction of, 26

Giant birds, reasons for distribution and flightlessness, 153

Giant Moa, 141 leg compared with that of horse, 152*

Giant Sloth, domesticated by man, 224 struggle between, 46

Giant Sloth, tracks at Carson City, 46

Gilfort, Robert, 157

Great Auk, extermination of, 232

Grouse on Scotch moors, 235

Hawkins, B. W., restorations by, 137

Hesperornis, description of, 80 impressions of feathers, 132 position of legs, 83, 84 restoration of, 82*

Hippotherium, 166, 167

Hoactzin, habits of, 74, 75*

Horn does not petrify, 130

Horse, abundant in Pleistocene time, 164 books on, 176 of bronze age, 163, 167 collections of fossil, 176 development of, 167, 168,* 175 differences between fossil and living, 163 early domestication, 165 evidence as to genealogy, 170-173 extra-toed, 172, 173 found in South America in 1530, 165 of Julius Cæsar, 172 none found wild in historic times, 165 Pliocene, 166 possibility of existence in America up to the time of its discovery, 169, 170 primitive, 160, 161*

Horse, sketched by primitive man, 163 teeth of, 170 three-toed, 166

Humming-bird, exterminated by hurricane, 231

Hydrarchus, 62*

Hyracotherium, 160, 161,* 170, 174

Ichthyosaurs, silhouettes of, 132

Iguanodons, found at Bernissart, 104

Impressions of feathers, 131 of scales, 131 of skin, 131

Inbreeding, effects of, 231, 232

Information, sources of, xvi

Innuits, habits, 192

Interdependence of animals and plants, 234, 235, 238

Ivory, fossil, 2, 4, 188, 189

Jaw of Mosasaur, 54* of reptiles, 53

Killing of the Mammoth, story, 177, 193

Kimmswick, deposit of Mastodon bones, 209

Knight, Charles R., restorations by, xviii, 136

Koch's Hydrarchus, 61, 62* Missourium, 207,* 208

Leaves, impressions of, 3, 13

Leg of Brontornis, 149*

Leg of the Great Brontosaurus, 96* of Giant Moa, 152* position in Hesperornis, 83 position in ducks, 84

Lenape Stone, 215, 216, 219*

Life, earliest traces of, 21, 34

Lingula, antiquity of, 228 Professor Brooks on, 229

Loricaria, 24*

Mammoth, adapted to a cold climate, 134 Alaskan Live, Story, 190 believed to live underground, 178 bones taken for those of giants, 185 contemporary with man, 189 derivation of name, 178 description, 179 discovery of entire specimens, 183, 187 distribution, 184, 186 drawn by early man, 189, 197* entire specimens obtainable, 194 reasons for extermination, 188 killing of the, 177 literature on, 197 misconception as to size, 179 mounted skeleton, 179 not now living, 190 preservation of remains, 187 skeletons in Alaska, 181, 195

Mammoth, in Chicago Academy of Sciences, 179 at St. Petersburg, 183* restoration, 176* size, 179, 180, 181 size of tusks, 181, 196 teeth, 196, 199* teeth dredged in North Sea, 184 tusks brought into market, 188, 189

Man contemporary with Mammoth, 189 fossil, 13 of Guadeloupe, 13

Manatees killed by cold, 230

Marsh, Prof. O. C., collection of fossil horses, 176 on Dinosaurs, 222 on toothed birds, 79, 89

Mastodon, bones taken for those of giants, 205 thought to be carnivorous, 206 covering, 210 description, 210 distribution, 203, 210, 212 extinction, 212 literature, 218 and man, 215, 216 first noticed in America, 204 origin unknown, 202 remains abundant, 208, 209 remains in Ulster and Orange counties, New York, 204, 206 restoration, 210*

Mastodon, size, 211 skeletons on exhibition, 218 species, 203 teeth, 198, 199,* 218 tusks, 199, 200

Mesohippus, 167

Mimicry, not conscious, 128

Missourium of Koch, 207,* 208

Moas, collections of, 156, 157 contemporary with man, 143, 144 deductions from distribution, 143 destruction of, 143, 144 discovery of bones, 140 elephant-footed, 142 feathers of, 141 Giant, 141 supposed food of, 142 legends of, 139, 140 literature, 158 scientific names, 146 size of, 141 species of, 141

Moloch, an Australian lizard, 100*

Mosasaurs, abundance of, in Kansas, 52 books on, 69 collections of, 68 extinction of, 56 first discovery, 50 jaw of, 54*

Mosasaurs, range of, 49 restoration, 52* size of, 49, 50

Mylodon tracks at Carson City, 45

Names, scientific, reasons for using, xvi, xvii

Nature, balance of, 238

Nuts, fossil, 11

Oldest animals, 21 vertebrates, 19, 22

Ostrich egg, 147

Over-specialization, 221, 222

Peale, C. W., 205

Peale, Rembrandt, 205, 206

Pelican, mandible, 53

Penguins, depend on fat for warmth, 127 feathers highly modified, 128 swim with wings, 80

Petrified bodies, 10

Phororhacos, description of, 149 mistaken for mammal, 149 Patagonian bird, 148 related to heron family, 152 restoration, frontispiece skull, 150, 151*

Protohippus, 166

Pteraspis, 28

Pterichthys, 25, 28, 32* mistaken for crab, 25

Pterodactyls, impressions of wings, 133 from Kansas, 55 wing, 72*

Pycraft, W. P., restoration of Archæopteryx, 89

Radiolarians, 15, 17*

Reconstruction of animals, 127, 130, 134

Reptiles, fasting powers of, 98 growth throughout life, 102 jaws, 53

Restorations, xviii Archæopteryx, 89* Ceratosaurus, 106* Hesperornis, 82* Mammoth, 176* Mastodon, 210* Phororhacos, frontispiece progress in, 137 Stegosaurus, 108* Thespesius, 90* Triceratops, 126* Tylosaurus, 52*

Reversion of fancy stock, 171

Rhinoceros, exterminated by cold, 232

Roc, legend of, 144, 145

Rocks, thickness of sedimentary, 20

Ruffles on dresses, 202

Schuchert, Charles, on collecting fossils, 17 collector of Zeuglodon bones, 63

Seals, covering of, 128

Sea-serpent, belief in, 56 possibility of existence, 57

Shaler, Professor, on changes in Miocene flora of Europe, 236, 237

Sharks, early, 31 Great-toothed, 65 known from spines and teeth, 29 Port Jackson, 29 teeth of, 69 White, or Man-Eater, 65

Skeleton, basis of all restorations, 127 best testimony of animal's relationships, 124 information to be derived from, 120, 122, 123, 124, 125, 126, 127 a problem in mechanics, 102, 124 reconstruction of, 120 relation of, to exterior of animal, 121, 127 of Triceratops, 103,* 121

Spines and plates, 130

Stegosaurus, description of, 106 restoration of, 108*

Survival of the fittest, 173

Teeth, birds with, 79 of gnawing animals, 169, 200 of grass-eaters, 169

Teeth, of horse, 170 of mammoth, 198, 199* of mastodon, 198, 199* of sharks, 29, 30 of Thespesius, 105

Thespesius, abundance of, 104, 105 brain of, 93 (Same as Claosaurus) engulfed in quicksand, 8 impressions of skin, 132 restoration of, 90* teeth of, 105 at Yale, 109

Tiger, preying on reindeer, 134

Tile-fish, destruction of, 230

Titanichthys, 28, 29

Toothed birds, collections of, 88 discovery of, 79

Townsend C. H., 190-192

Tracks, ascribed to birds, 38 ascribed to giants, 45 animals known from, 41 collections of, 47 of Connecticut Valley, 37 deductions from, 44 of Dinosaurs, 38,* 40,* 41, 47* discovery in England and America, 37, 42 how formed, 35, 40 at Hastings, 44

Tracks, of Mylodon, 46 of worms, 3, 33

Triceratops, brain, 94 broken horn, 102 description, 100, 101 restoration, 126* skeleton, 103*

Tufa, 14

Tukeman, killing of the Mammoth, 177, 193

Variation in animals, 228

Vertebrates, oldest, 22

Vestigial structures, 201, 202

Volcanic outbursts, 231, 232

Webster, F. S., on destruction of gar pikes, 26

White, C. A., on the nature and uses of fossils, 17

White Shark, 65

Wings, 71, 72,* 73 of embryonic birds, 73

Wood, fossil, 9, 10

Worm trails, 3, 33

Yucca, fertilization, 235

Zeuglodon, abundance of remains, 60 same as Basilosaurus description, 58, 63 habits, 59

Zeuglodon, Koch's restoration, 62 name, 58, 69 once numerous, 60 size, 58 specimen of, 68 structure of bones, 64 teeth, 58, 69*

End of Project Gutenberg's Animals of the Past, by Frederic A. Lucas