[9]The name is derived from two Greek words—plesios, near, or allied to, andsauros, a lizard.
[9]The name is derived from two Greek words—plesios, near, or allied to, andsauros, a lizard.
A glance at our illustration,Plate III., will show that this strange creature was not inaptly compared at the time to a snake threaded through the body of a turtle.
Dr. Buckland truly observes that the discovery of this genus forms one of the most important additions that geology has made to comparative anatomy. “It is of the Plesiosaurus,” says that graphic author, in hisBridgewater Treatise, “that Cuvier asserts the structure to have been the most heteroclite, and its characters altogether the most monstrous that have been yet found amid the ruins of a former world. To the head of a lizard it united the teeth of a crocodile; a neck of enormous length, resembling the body of a serpent; a trunk and tail having the proportions of an ordinary quadruped; the ribs of a chameleon, and the paddles of a whale! Such are the strange combinations of form and structure in the Plesiosaurus—a genus, the remains of which, after interment for thousands of years amidst the wreck of millions of extinct inhabitants of the ancient earth, are at length recalled to light by the researches of the geologist, and submitted to our examination in nearly as perfect a state as the bones of species that are now existing upon the earth.”
Perhaps the best way in which we can gain a clear idea of the general characters of a long-necked sea-lizard, as we may call our Plesiosaurus, is by comparing it with the fish-lizard, described in the last chapter. Its long neck and small head are the most conspicuous features. Then we notice the short tail. But if we compare the paddles of these two extinct forms of life, we notice at once certain important differences. In the fish-lizard the bone of the arm was very short, while all the bones of the fore-armand fingers were modified into little many-sided bodies, and so articulated together as to make the whole limb, or paddle, a solid yet flexible structure. In the long-necked sea-lizard, however, we find a long arm-bone with a club-like shape; and the two bones of the fore-arm are seen to be longer than in the fish-lizard. But a still greater difference shows itself in the bones of the finger, as we look at a fossilised skeleton (or a drawing of one); for the fingers are long and slender, like those of ordinary reptiles.
There are only five fingers, and each finger is quite distinct from the others. This is the reason why the Plesiosaur was considered to depart less from the type of an ordinary reptile, and so received its name. Other remarkable differences present themselves in the shoulders and haunches, but these need not be considered here. The species shown inFig. 8had rather a large head. It is obvious that such a long slender neck as these creatures had could not have supported a large head, like that of the fish-lizard. Consequently, we find a striking contrast in the skulls of the two forms. That of the Plesiosaur was short and stout, and therefore such as could easily be supported, as well as rapidly moved about by the long slender neck. Thus we find another simple illustration of the “law of correlation,” alluded to onp. 6. The teeth were set in distinct sockets, as they are in crocodiles, to which animals there are also points of resemblance, in the backbone, ribs, and skull.Fig. 7shows three different types of lower jaws of Plesiosaurs. The one marked C belongs to Plesiosaurus dolichodeirus, the species represented in our plate. There were no bony plates in the eye. Professor Owen thinks that they were long-lived. The skin was probably smooth, like that of a porpoise.
Plate III.
PTERODACTYLS. LONG-NECKED SEA-LIZARD. CUTTLE-FISH OR BELEMNITE.Plesiosaurus dolichodeirus.Length 22 feet.
Fig. 7.—Mandibles of Fish-lizards.A,Peloneustes philarchus(Seeley); from the Oxford Clay.B,Thaumatosaurus indicus(Lydekker); Upper Jurassic of India.C,Plesiosaurus aolichodirus(Conybeare); from the Lower Lias, Lyme Regis.
The visitor to the geological collection at South Kensington will find a splendid series of the fossilised remains of long-necked sea-lizards. They were mostly obtained from the Lias formation of Street in Somersetshire, Lyme-Regis in Dorset, and Whitby in Yorkshire. Those from the Lias are mostly small, about eight to ten feet in length. But in the rocks of the Cretaceous period, which was later, are found larger specimens. There is a cast of a very fine specimen from the Upper Lias on the wall of the east corridor (No. 3 on Plan) of the geological galleries at South Kensington, which is twenty-two feet long. But some of the Cretaceous forms, both in Europe and America, attained a length of forty feet, and had vertebræ six inches in diameter. The bodies of the vertebræ, or “cup-bones,” are either flat or slightlyconcave, showing that the backbone as a whole was less flexible than in the fish-lizards.
Fig. 8.—Plesiosaurus macrocephalus.
It may be mentioned here that Mr. Smith Woodward, of the Natural History Museum, recently showed the writer a fossil Plesiosaur that is being set up in the formatore’s shop, in the same manner that a recent skeleton might be. In this, and many other ways, the guardians of the national treasure-house are endeavouring to make the collection intelligible and interesting to the general public. Specimens of extinct animals thus set up, give one a much better idea than when the bones are all lying huddled together on a slab of rock. But it is not always possible to get the bones entirely out of their rocky bed, or matrix.Great credit is due to Mr. Alfred N. Leeds, of Eyebury, who has disinterred the separate bones of many distinct skeletons of Plesiosaurs from Oxford Clay strata near Peterborough.
It will be remembered that the long and powerful tail of the fish-lizard was its principal organ of propulsion through the water; and that, consequently, the paddles only played a secondary part. They were small, but amply large enough for the work they had to perform. But our long-necked sea-lizards possessed very short tails. What, then, was the consequence? Obviously that the paddles had all the more work to do. They were the chief swimming organs. The vertebræ of this short tail show that it probably was highly flexible, and could move rapidly from side to side; but, for all that, its use as a propeller would not be of much importance. We see now why the paddles are so long and powerful, like two pairs of great oars, one pair on each side of the body. In a fossil skeleton you will notice the flattened shape of the arm-bone (or humerus), and of the thigh-bone (or femur). This gave breadth to the paddles, and made them more efficient as swimming organs. They give no indication of having carried even such imperfect claws as those of turtles and seals, and therefore we may conclude that the Plesiosaur was far more at home in the water than on land, and it seems probable that progression on land was impossible.
The tail was probably useful as a rudder, to steer the animal when swimming on the surface, and to elevate or depress it in ascending and descending through the water. Like the fish-lizard, this creature was an air-breather, and therefore was obliged occasionally to visit the surface for fresh supplies of air. But probably it possessed the power of compressing air within its lungs, so that the frequency of its visits to the surface would not be very great.
From the long neck and head, situated so far away from the paddles, as well as for other reasons, it may be concluded that this creature was a rapid swimmer, as was the Ichthyosaurus.Although of considerable size, it probably had to seek its food, as well as its safety, chiefly by artifice and concealment. The fish-lizard, its contemporary, must have been a formidable rival and a dangerous enemy, whom to attack would be unadvisable.
Speaking of the habits of the long-necked sea-lizard, Mr. Conybeare, in his second paper, already alluded to, says, "That it was aquatic, is evident from the form of its paddles; that it was marine, is almost equally so, from the remains with which it is universally associated; that it may occasionally have visited the shore, the resemblance of its extremities to those of the turtle may lead us to conjecture; its motion, however, must have been very awkward on land; its long neck must have impeded its progress through the water, presenting a striking contrast to the organisation which so admirably fits the Ichthyosaurus to cut through the waves.
“May it not therefore be concluded (since, in addition to these circumstances, its respiration must have required frequent access of air) that it swam upon or near the surface, arching back its long neck like the swan, occasionally darting it down at the fish which happened to float within its reach? It may, perhaps, have lurked in shoal-water along the coast, concealed among the sea-weed, and, raising its nostrils to a level with the surface from a considerable depth, may have found a secure retreat from the assaults of dangerous enemies; while the length and flexibility of its neck may have compensated for the want of strength in its jaws and its incapacity for swift motion through the water, by the suddenness and agility of the attack which they enabled it to make on every animal fitted for its prey, which came within its extensive sweep.”
More than twenty species of long-necked sea-lizards are known to geologists.
Professor Owen, in his great work onBritish Fossil Reptiles, when describing the huge Plesiosaurus dolichodeirus from Dorset, suggests that the carcase of this monster, after it sank to thebottom of the sea, was preyed upon by some carnivorous animal (perhaps sharks). It seems, he says, as if a bite of the neck had pulled out of place the eighth to the twelfth vertebræ. Those at the base of the neck are scattered and dispersed as if through more “tugging and riving.” So with regard to its body, probably some hungry creature had a grip of the spine near the middle of the back, and pulled all the succeeding vertebræ in the region of the hind limbs. Thus we get a little glimpse of scenes of violence that took place at the bottom of the bright sunny seas of the period when the clays and limestones of the Lias rocks were being deposited in the region of Lyme-Regis.
As time went on, these curious reptiles increased in size, until, in the period when our English chalk was being formed (Cretaceous period), they reached their highest point (seep. 147). After that they became extinct—whether slowly or somewhat suddenly we cannot tell.
Until more is known of the ancient life of the earth, it will not be possible to say with certainty what were the nearest relations of the long-necked sea-lizards. They first appear in the strata of the New Red Sandstone, which is below the Lias. Certain little reptiles, about three feet long, from the former rocks, known as Neusticosaurus and Lariosaurus, seem to be rather closely related to the creatures we are now considering, and to connect them with another group, namely, the Pliosaurs. They were partly terrestrial and partly aquatic; but it is not easy to say whether their limbs had been converted into true paddles or not. At any rate, there is every reason to believe that the long-necked sea-lizards were descended from an earlier form of land reptile. They gradually underwent considerable modifications, in order to adapt themselves to an aquatic life. We noticed that the same conclusion has been arrived at with regard to the fish-lizards. Both these extinct groups, therefore, present an interesting analogy to whales, which are now considered to have been derived, by a like series of changes, from mammals that once walked the earth.
The Plesiosaur presents, on the one hand, points of resemblance to turtles and lizards,—on the other hand, to crocodiles, whales, and, according to some authorities, even the strange Ornithorhynchus. But it will be very long before its ancestry can be made known. In the mean time, we must put it in a place somewhere near the fish-lizards, and leave posterity to complete what has at present only been begun. It must, however, be borne in mind that some of the above resemblances are purely accidental, and not such as point to relationship. Because their flippers are like those of a whale, it does not mean that Plesiosaurs are related to modern whales. It only means that similar habits tend to produce accidental resemblances—just as the whales and porpoises, in their turn, resemble fishes. To make torpedoes go rapidly through the water, inventors have given them a fish-like shape;—in the same way the early forms of mammals, from which whales are descended, gradually adapted themselves to a life in the water, and so became modified to some extent to the shapes of fishes.
The Pliosaurs, above mentioned, are evidently relations, but with short necks instead of long ones. They had enormous heads and thick necks. Fine specimens of their huge jaws, paddle-bones, etc., may be seen at the end of the reptile-gallery at Cromwell Road. One of the skulls exhibited there is nearly six feet long, while a hind paddle measures upwards of six and a half feet in length, of which thirty-seven inches is taken up by the thigh-bone alone. The teeth at the end of the jaws are truly enormous. One tooth, from a deposit known as the Kimmeridge Clay, is nearly a foot long from the tip of the crown to the base of the root. In some, the two jaw-bones of the lower jaw are partly united, as in the sperm-whale or cachalot. Creatures so armed must have been very destructive.
CHAPTER V.
THE DRAGONS OF OLD TIME—DINOSAURS.
“What we know is but little; what we do not know is immense.”—La Place.
Was there ever an age of dragons? Tradition says there was; but there is every reason to believe that the fierce and blood-thirsty creatures, of which such a variety present themselves, are but creations of the imagination,—useful in their way, no doubt, as pointing a moral or adorning a tale, but, nevertheless, wholly without foundation in fact. The dragon figures in the earliest traditions of the human race, and crops up again in full force in European mediæval or even late romance.
In ancient Egyptian mythology, Horus, the son of Isis, slays the evil dragon. In Greece, the infant Hercules, while yet in his cradle, strangles deadly snakes; and Perseus, after engaging in fierce struggle with the sea-monster, slays it, and rescues Andromeda from a cruel death. In England, we have the heroic legend of St. George and the Dragon depicted on our sovereigns. But it is easy to see a common purpose running through these legends. They are considered by many to be solar myths, and have a moral purpose. The dragons or snakes are emblems of darkness and evil; the heroes emblems of light, and so of good. The triumph of good over evil is the theme they were intended to illustrate. The dragons, then, are clearly products of the imagination, based, no doubt, on the huge and uncouth reptiles of the present human era, such as crocodiles, pythons, and such creatures.
Amidst much diversity there is yet a strange similarity in the dragons that figure in the folk-lore of Eastern and Western peoples. Probably our European traditions were brought by the tribes which, wave after wave, poured in from Central Asia.
They are, for the most part, unnatural beasts, breathing out fire, and often endowed with wings, while at the same time possessing limbs ending in cruel claws, fitted for clutching their unfortunate victims. The wings seem, to say the least, very much in the way. Poisonous fangs, claws, scaly armour, and a long pointed tail were all very well,—but wings are hardly wanted, unless to add one more element of mystery or terror. Some, however, are devoid of wings: the Imperial Japanese dragons showing no sign of such appendages. The Temple Bar griffin is a grim example of a winged monster. Nevertheless, in spite of all the manifest absurdities of the dragons of various nations and times, geology reveals to us that there once lived upon this earth reptiles so great and uncouth that we can think of no other but the time-honoured word “dragon” to convey briefly the slightest idea of their monstrous forms and characters.
So there is some truth in dragons, after all. But then we must make this important reservation—viz. that the days of these dragons were long before the human period; they flourished in one of those dim geological ages of which the rocks around us bear ample records.
It is a strange fact that human fancy should have, in some cases at least, created monsters not very unlike some of those antediluvian animals that have, during the present century, been discovered in various parts of Europe and America. Some unreasonable persons will have it that certain monstrous reptiles of the Mesozoic era, about to be described, must have somehow managed to survive into the human period, and so have suggested to early races of men the dragons to which we have alluded. But there is no need for this untenable supposition. By a free blending together of ideas culled from living types of animals itwould be very easy to construct no small variety of dragons; and so we may believe this is what the ancients did.
Having said so much of dragons in general, let us proceed to consider those both possible and real monsters revealed of late years by the researches of geologists. For this purpose we shall devote the present and two following chapters to the consideration of a great and wonderful group of fossil reptiles known as Dinosaurs. The strange fish-lizards and sea-lizards previously described were the geological contemporaries of a host of reptiles, now mostly extinct, which inhabited both the lands and waters of those periods known as the Triassic, Jurassic, and Cretaceous, which taken together represent the great Mesozoic, formerly called the Secondary, era.
The announcement by Baron Cuvier—the illustrious founder of Palæontology—that there was a period when our planet was inhabited by reptiles of appalling magnitude, with many of the features of modern quadrupeds, was of so novel and startling a character as to require the prestige of even his name to obtain for it any degree of credence. But subsequent discoveries have fully confirmed the truth of his belief, and the “age of reptiles” is no longer considered fabulous. This expression was first used by Dr. Mantell as the title of a paper published in theEdinburgh Philosophical Journalin 1831, and serves to remind us that reptilian forms of life were once the ruling class among animals.
The Dinosaurs are an extinct order comprising the largest terrestrial and semi-aquatic reptiles that ever lived; and while some of them in a general way resembled crocodiles, others show in the bony structures they have left behind a very remarkable and interesting resemblance to birds of the ostrich tribe. This resemblance shows itself in the pelvis, or bony arch with which the hind limbs are connected in vertebrate or backboned animals, and in the limbs themselves. This curious fact, first brought into notice by Professor Huxley, has been variously interpretedby anatomists; some concluding, with Professor Huxley, that birds are descended from Dinosaurs; while others, with Professor Owen, consider the resemblance accidental, and in no way implying relationship. Huxley has proposed the name Ornithoscelida, or bird-legged, for these remarkable reptiles.
Dinosaurs must have formerly inhabited a large part of the primæval world; for their remains are found, not only in Europe, but in Africa, India, America, and even in Australia; and the geologist finds that they reigned supreme on the earth throughout the whole of the great Mesozoic era.
Their bodies were, in some cases, defended by a formidable coat of armour, consisting of bony plates and spines, as illustrated by the case of Scelidosaurus (p. 105), thus giving them a decidedly dragon-like appearance. The vertebræ, or bony segments of the backbone, generally have their centra hollow on both sides, as in the Ichthyosaurus; but in the neck and tail they are not unfrequently hollow on one side and convex on the other. In some of the largest forms the vertebræ are excavated into hollow chambers. This is apparently for the sake of lightness; for a very large animal with heavy solid bones would find it difficult to move freely. In this way strength was combined with lightness.
All the Dinosaurs had four limbs, and in many cases the hind pair were very large compared to the fore limbs. They varied enormously in size, as well as in appearance. Thus certain of the smaller families were only two feet long and lightly built; while others were truly colossal in size, far out-rivalling our modern rhinoceroses and elephants.
The limbs of Cetiosaurus, for example, or of Stegosaurus, remind us strikingly of those of elephants. The celebrated Von Meyer was so struck with this likeness that he proposed the name Pachypoda for them, which means thick-footed. Professor Owen opposed this name; for it was misleading, and only applied to a few of them. He therefore proposed the name we have alreadybeen using, viz. Dinosauria,[10]and this name has been generally retained. We are thus led to connect them with lizards and crocodiles, rather than with birds or quadrupeds. The strange and curiously mixed characters of the old-fashioned reptiles is forcibly illustrated by these differences of opinion among leading naturalists. Professor Seeley, another living authority, refuses to consider them as reptiles, at least in the ordinary sense of the word.
[10]Greek—deinos, terrible;sauros, lizard.
[10]Greek—deinos, terrible;sauros, lizard.
Extinct forms of life are often so very different to the creatures inhabiting the world of to-day, that naturalists find it a hard task to assign them their places in the animal kingdom. The classes, orders, and families under which living forms are grouped are often found inadequate for the purpose, so much so that new orders and new families require to be made for them; and then it is often quite impossible to determine the relations of these new groups to the old ones we are accustomed to. Dinosaurs offer a good example of this difficulty. Were they related to ancient crocodiles? No one can say for certain; but it is quite possible, and even probable. Again, did certain long-legged Dinosaurs eventually give rise by evolution to the running birds, ostriches, emeus, etc.? This, although supported by weighty authority, is a matter of speculation: we ought to be very careful in accepting such conclusions. It may perhaps be safer to look upon the ancestry of birds as one of those problems on which the oracle of science cannot at present declare itself.
Various attempts have been made to classify Dinosaurs, and arrange them in family groups; but, considering our imperfect knowledge, it will be wise to regard all such attempts as purely temporary and provisional, although in some ways convenient. Professor Marsh, of Yale College, U.S., whose wonderful discoveries in the far West have attracted universal attention, has grouped the Dinosaurs into five sub-orders. It will, however, be sufficient for our purpose if we follow certain English authorities whodivide them into three groups—taking the names given by Professor Marsh, only running together some which he would separate.
We shall first consider the very interesting and huge forms included in his sub-order the Sauropoda, or lizard-footed Dinosaurs. Various parts of the skeletons, such as vertebræ, leg-bones, etc., of these cumbrous beasts have long been known in this country; but Professor Marsh was the first person to discover a complete skeleton.
We shall, therefore, now turn our attention to the bony framework of the huge Brontosaurus (Fig. 9), a vegetable-feeding lizard. But it will be necessary to completely lay aside all our previous notions taken from lizards of the present day, with their short legs and snake-like scaly bodies, before we can come to any fair conclusion with regard to this monstrous beast.
It was nearly sixty feet long, and probably when alive weighed more than twenty tons! that it was a stupid, slow-moving reptile, may be inferred from its very small brain and slender spinal cord. By taking casts of the brain-cavities in the skulls of extinct animals, anatomists can obtain a very good idea of the nature and capacity of their brains; and in this way important evidence is obtained, and such as helps to throw light upon their habits and general intelligence. No bony plates or spines have been discovered with the remains of this monster; so that we are driven to conclude that it was wholly without armour: and, moreover, there seem to be no signs of offensive weapons of any kind.
Professor Marsh concludes that it was more or less amphibious in its habits, and that it fed upon aquatic plants and other succulent vegetation. Its remains, he says, are generally found in localities where the animal had evidently become mired, just as cattle at the present day sometimes become hopelessly fixed in a swampy place on the margin of a lake or river (seep. 19). Each track made by the creature in walking occupied one square yard in extent!
Fig. 9.—Restored skeleton ofBrontosaurus excelsus. (After Marsh.)Click on image to view larger version.
The remarkably small head is one of the most striking features of this Dinosaur, and presents a curious contrast to the large and formidable skulls possessed by some other forms to be described further on. But it is clear that no animal with such a long neck as this creature had could have borne the weight of a heavy skull. Short thick necks and heavy skulls always go together. Indeed, the weight of the long neck itself would have been serious had it not been for the fact that the vertebræ in this part of the skeleton, and as far as the region of the tail, have large cavities in the sides of the centra. This cavernous structure of the vertebræ gradually decreases towards the tail. The cavities communicated with a series of internal cavities which give a kind of honeycombed structure to the whole vertebra. This arrangement affords a combination of strength and lightness in the massive supports required for the huge ribs, limbs, and muscles, such as could not have been provided by any other plan. (SeeFig. 10.)
Fig. 10.—Neck vertebræ ofBrontosaurus.1. Front view.2. Back view.
Plate IV.
A GIGANTIC DINOSAUR, BRONTOSAURUS EXCELSUS.Length nearly 60 feet.
The body of the Brontosaur was comparatively short, with a fairly large paunch (see restoration,Plate IV.). The legs and feet were strong and massive, and the limb-bones solid. As if partly in order to balance the neck, we find a long and powerful tail, in which the vertebræ are nearly all solid. In most Dinosaurs the fore limbs are small compared to the hind limbs—e.g.Megalosaurus, Iguanodon, and Scelidosaurus,—but here we find them unusually large. In this case, then, it is hardly possible that the creature walked upon its hind legs, as many of the Dinosaurs did. But, at the same time, we may believe that occasionally it assumed a more erect position; and may not the light hollowed structure of the vertebræ in the fore part of the body, already alluded to, have imparted such lightness as made it possible for the creature to assume such attitudes? There can be little doubt but that many other fierce and formidable Dinosaurs were living at the same time and in the same region with Brontosaurus, whose remains are found in the Jurassic rocks of Colorado (Atlantosaurus beds).
How this apparently helpless and awkward animal escaped in the struggle for existence it is not easy to conjecture; but since there is reason to believe it was more or less at home in the water, and could use its powerful tail in swimming, we may perhaps find a way out of the difficulty by supposing that, when alarmed by dangerous flesh-eating foes, it took to the water, and found discretion to be the better part of valour. Although apparently stupid, the Brontosaur probably possessed a good deal of cunning, and we can fancy it stretching its long neck above reeds, ferns, and cycads to get a view of the approaching enemy.
The Sauropoda, or lizard-footed Dinosaurs, show in many ways a decided approach to a simple or generalised crocodile; so much so, that Professor Cope is inclined to include crocodiles and sauropodous Dinosaurs in the same order. Still, there are important differences in other members of this sub-order. Unfortunately, our knowledge is at present rather limited, owing to the want of complete skeletons. Vertebræ, limb-bones, skulls, and teeth have all been discovered through the zeal and energy ofProfessor Marsh and his comrades, in the far west of America, as well as by the researches of English geologists, assisted by the labours of many ardent collectors of fossils, in this country. Some of these may now be briefly considered.
InPlate V.we have endeavoured to give some idea of a huge thigh-bone (femur) belonging to the truly gigantic Dinosaur called Atlantosaurus. It is six feet two inches long, and a cast of it may be seen in the fossil reptile gallery of the British Museum of Natural History (Wall-case No. 3). It should be mentioned, however, that the original specimen is partly restored, so that its exact length to an inch or so is not quite certain. In our illustration it is shown to be a little taller, when placed upright, than a full-grown man. Professor Marsh, the fortunate discoverer of this wonderful bone, calculates that the Atlantosaurus must have attained a length of over eighty feet! and, assuming that it walked upon its hind feet, a height of thirty feet!
It doubtless fed upon the luxuriant foliage of the sub-tropical forests, portions of which are preserved with its remains. Besides this thigh-bone, Professor Marsh has procured specimens of vertebræ from the different parts of the vertebral column; but no skull or teeth. The vertebræ are hollowed out much in the same way as those of Brontosaurus. The fore limbs were large, as in the latter animal; and the extremities of the limbs were provided with claws. Taking all present evidence, it appears that the Atlantosaurus bore a general resemblance to its smaller contemporary. We can therefore form a fairly good idea of its aspect and proportions.
The same Jurassic strata from the Rocky Mountains have yielded remains of another big Dinosaur, belonging to the same family. This genus, which has been named the Apatosaurus, is represented by a nearly complete skeleton, in the Yale College Museum; and is fortunately in an excellent state of preservation. Another species, of smaller size, though not so complete, adorns the same collection. This was about thirty feet long, and is known as Apatosaurus grandis.
Plate V.
THIGH-BONE OF THE LARGEST OF THE DINOSAURS, ATLANTOSAURUS.From a cast in the Natural History Museum. Length 6 feet 2 inches.
Morosaurus, another important genus, is known from a large number of individuals discovered in the now famous Atlantosaurus beds of Colorado, including one nearly complete skeleton. The head of this creature was small; the neck elongated; and the vertebræ of the neck are lightened by deep cavities in their centra, similar to those in birds of flight. The tail, also, was long. When alive, this Dinosaur was about forty feet in length. It probably walked on all fours; and in many other respects was very unlike a typical Dinosaur. The brain was small, and it must have been sluggish in all its movements. The nearly complete remains of Morosaurus grandis were found together in a very good state of preservation in Wyoming, and many of the bones lay just in their natural positions.
Diplodocus, of which several incomplete specimens have been discovered, was intermediate in size between Atlantosaurus and Morosaurus, and may have reached when living, a length of forty or fifty feet. Its skull was of moderate size, with slender jaws. The teeth were weaker than those of any other known Dinosaur, and entirely confined to the front of the jaws. Professor Marsh concludes from the teeth that Diplodocus was herbivorous, feeding on succulent vegetation, and that it probably led an aquatic life.Fig. 11shows its skull.
The remains of this interesting Dinosaur (Brontosaurus), which in several ways differs from other members of the “lizard-footed” group, were found in Upper Jurassic beds, near Cañon City, Colorado. A second smaller species was also discovered near Morrison, Colorado. All the remains lay in the Atlantosaurus beds. These strata—the tomb in which Nature has buried up so many of her dragons of old time—can be traced for several hundred miles on the flanks of the Rocky Mountains, and are always to be known by the bones they contain. They lie above the Triassic strata and just below the Sandstone of the Dakota group. Some have regarded them as of Cretaceous age; but, judging from their fossils, there can be but little doubt that they were depositedduring the Jurassic period—probably in an old estuary. They consist of shale and sandstone.
Besides the numerous Dinosaurs, Professor Marsh’s colleagues have found abundant remains of crocodiles, tortoises, and fishes, with one Pterodactyl, a flying reptile (seechap. viii.), and several small marsupials. The wonderful collection of American Jurassic Dinosaurs in the Museum of Yale College includes the remains of several hundred individuals, many of them in excellent preservation, and has afforded to Professor Marsh the material for his classification already alluded to.
Fig. 11.—Head ofDiplodocus.1. Side view.2. Front view.
English Dinosaurs of the Lizard-footed Group.
Unfortunately, there are at present no complete skeletons known of English Dinosaurs related to the American forms above described. But, since the English fossils were first in evidence by many years, and Marsh’s discoveries have confirmed in a remarkable way conclusions drawn by Owen, Huxley, Hulke, and Seeley, and others from materials that were rather fragmentary, it may be worth while to give some account of these remains and the interpretations they have received.
Dr. Buckland, in hisBridgewater Treatise, 1836, referred toa limb-bone in the Oxford Museum, from the great Oolite formation near Woodstock, which was examined by Cuvier, and pronounced to have once belonged to a whale; also a very large rib, which seemed whale-like. In 1838 Professor Owen, when collecting materials for his famousReport on the Fossil Reptiles of Great Britain, inspected this remarkable limb-bone, and could not match it with any bones known among the whale tribe; and yet its structure, where exposed, was like that of the long bone (humerus) of the paddle of a whale. Later on, he abandoned the idea that it once belonged to a whale, and it was thought that the extinct animal in question might have been a reptile of the crocodilean order. In time, a fine series of limb-bones and vertebræ was added to the Oxford Museum by Professor Phillips (Dr. Buckland’s successor at Oxford), who pronounced them to be Dinosaurian. The name “Cetiosaurus”[11](or Whale-lizard), originally given by Owen, was unfortunate, because there is really nothing whale-like about it, except a certain coarse texture of some of the bones.
[11]Greek—ketion, whale;sauros, lizard.
[11]Greek—ketion, whale;sauros, lizard.
In 1848 Dr. Buckland announced the discovery of another limb-bone (a femur), which Owen referred to Cetiosaurus; it was four feet three inches in length. Between 1868 and 1870, however, a considerable portion of a skeleton was discovered in the same formation at Kirtlington Station, near Oxford. These remains were the subject of careful examination by Professors Owen and Phillips. The femur this time was five feet four inches long. Their studies threw much light on the nature and habits of Cetiosaurus.
Although showing in many ways an approach to the crocodile type of reptile, yet it was perceived from the nature of the limbs that they were better fitted for walking on land than are those of a crocodile, with its sprawling limbs. Still, Professor Owen was careful to point out that the vertebræ of its long tail indicate suitability as a powerful swimming organ, and concluded that thecreature was more aquatic than terrestrial in its habits. Plaster casts of the limb-bones may be seen at the British Museum of Natural History, side by side with the huge Atlantosaurus cast sent by Professor Marsh.
The Kimmeridge clay of Weymouth has yielded a huge arm-bone (or humerus), nearly five feet long; and from Wealden strata of Sussex and the Isle of Wight vertebræ have been collected. Altogether we have remains of Cetiosaurus from at least half a dozen counties. Unfortunately, no specimen of a skull has yet been found, and only two or three small and incomplete teeth, which may possibly have belonged to some other animal. Professor Owen estimated the length of the trunk and tail of the creature to have been thirty-five or thirty-six feet; but in the absence of further evidence it was not possible to form any conclusion as to its total length. It is evident that Cetiosaurus was closely allied to the American Brontosaurus (p. 69); and so these earlier English discoveries have gained much in interest from the light thrown upon them by Professor Marsh’s huge Saurian.
Another English Saurian of this group was the Ornithopsis, from Wealden strata in the Isle of Wight, which has been the subject of careful study by Mr. Hulke and Professor Seeley. Their conclusions, based on the examination of separate portions of the skeleton (such as vertebræ), have been singularly confirmed by the discovery of Brontosaurus.
In Ornithopsis the vertebræ of the neck and back, though of great size, were remarkably light, and yet of great strength. One of the vertebræ of the back had a body, or centrum, ten inches long. Hoplosaurus and Pelosaurus were evidently reptiles closely allied to the above types; but at present are so imperfectly known that we need not consider them here.
CHAPTER VI.
DINOSAURS (continued).
“Fossils have been eloquently and appropriately termed ‘Medals of Creation.’”—Dr. Mantell.
When any tribe of plants or animals becomes very flourishing, and spreads over the face of the earth, occupying regions far apart from one another, where the geographical and other conditions, such as climate, are unlike, its members will inevitably develop considerable differences among themselves.
During the great Mesozoic period, Dinosaurs spread over a large part of the world; they became very numerous and powerful. Just as the birds and beasts (quadrupeds) of to-day show an almost endless variety, according to the circumstances in which they are placed, so that great and powerful order of reptiles we are now considering ran riot, and gave rise to a variety of forms, or types. Those described in the last chapter were heavy, slow-moving Dinosaurs, of great proportions, and were all herbivorous creatures, apparently without weapons of offence or defence.
The group Theropoda, or “beast-footed” Dinosaurs, that partly form the subject of the present chapter, were all flesh-eating animals; and, as we shall discover from their fossilised remains, were of less size, and led active lives. In fact, they acted in their day the part played by lions and tigers to-day.
In the year 1824 that keen observer and original thinker, the Rev. Dr. Buckland, described to the Geological Society of London some remains of a very strange and formidable reptile found inthe Limestone of Stonesfield, near Woodstock (about twelve miles from Oxford). This rock, known as “Stonesfield slate” from its property of splitting up into thin layers, has long been celebrated for its fossil remains, and from it have also been obtained the bones of some early mammals. It is a member of the Lower Oolitic group.
The portions of skeleton originally discovered consisted of part of a lower jaw, with teeth, a thigh bone (femur), a series of vertebræ of the trunk, a few ribs, and some other fragments. The name Megalosaurus,[12]or “great lizard,” suggested itself both to Dr. Buckland and Baron Cuvier, because it was evident from the size of the bones that the creature must have been very big. It is true these bones were not found together in one spot; but Professor Owen came to the conclusion that they all belonged to the same species.