Chapter VII: The Empire of the Great Reptiles

Had we lived in the Carboniferous period, we might have supposed that the line of the great Labyrinthodont Batrachians would have been continued onward and elevated, perhaps, in the direction of the Mammalia, to which some features of their structure point. But we should have been mistaken in this. The Labyrinthodonts, it is true, extend into the Trias; but there is perhaps a sign of their coming degradation in the appearance in the Permian of the first known mud-eel, a humble Batrachian form allied to the Newts and Water-lizards.[62] Their special peculiarities are dropped in the Mesozoic in favour of those of certain small and feeble lizard-like animals, appearing first in the Carboniferous, and more manifestly in the Permian, and which are the true forerunners, though they can scarcely be the ancestors, of the magnificent reptilian species of the Mesozoic, which have caused this period to be called aEurooethe age of reptiles.aEuroŁ

The leading reptilian animal from the European Permian has long been the _Proterosaurus_, from the copper slates of Thuringia (Fig. 141), a reptile of lizard-like form, with well-developed limbs, and attaining a length of three or four feet. It resembles more nearly those large modern lizards known as aEurooeMonitors,aEuroŁ than any other existing form. The fore-limb represented in the figure foreshadows very closely the bones of the human arm and hand. Besides this we find in the Permian certain lizards (_Theriodonts_ of Owen) which present the remarkable and advanced peculiarity already predicted by some Carboniferous Microsauria,[63] of having distinct canine teeth, producing a division into incisors, canines, and molars, in the manner of the Carnivorous quadrupeds, which they seem also to have resembled in some other parts of their skeletons. It is not impossible that the footprints in the Permian sandstones of Scotland, which have been referred to tortoises, were those of animals of this type. Cope has recently described from the Permian of Texas a number of reptiles which have the complex dentition of the Theriodonts, and others which simulate that of Herbivorous mammals, by the possession of flat grinding teeth supposed to be adapted to vegetable food.[64] The teeth of all these Permian reptiles were set in sockets, also an advanced peculiarity. Thus already in the Permian, before the final decadence of the Carboniferous flora, and while the PalA|ozoic invertebrates still lingered in the sea, the age of reptiles dawned, and gave promise of its future greatness by the assumption on the part of reptilian species of structures now limited to the Mammalia.

But the great Mesozoic reptiles were not fully enthroned, till the Permian, an unsettled and disturbed age, characterised by great earth movements, had passed away, and until that period of continental elevation, with local deserts and desiccation, and much volcanic action, which we call the Trias, had also passed.

Then in the Jurassic and early Cretaceous the reptiles culminated, and presented features of magnitude and structural complexity unrivalled in later times. At the same time the Labyrinthodonts disappear, or are degraded into the humble stations which the modern Batrachians now occupy.

To understand the reptiles of this age, it will be necessary to notice the subdivisions of their modern representatives. The true reptiles now existing constitute the following orders:aEuro"1, the Turtles and Tortoises (_Chelonia_); 2, the Snakes (_Ophidia_); 3, the Lizards (_Lacertilia_); 4, the Crocodiles and Alligators (_Crocodilia_). All of these, except the snakes, are well represented among Mesozoic fossils; but we have in this middle age of the earthaEuro(TM)s geological history to add to them from five to seven orders now altogether extinct, and these not of low and inferior organisation, but including species far in advance of any now existing both in elevation and magnitude, and constituting the veritable aristocracy of the reptile race. It will best serve our purpose here to consider chiefly these perished orders and their history, and then to notice very shortly those that now survive.

The first of the extinct orders is that of the great Sea-lizards,[65] of which the now familiar _Ichthyosaurus_ and _Plesiosaurus_ of the English seas, to be seen in all museums and text-books, are the types (Figs. 142, 142_a_ and 142_b_). These were marine animals of large size, but not fishes or amphibians. They were true air-breathing reptiles, but with paddles for swimming instead of feet, and some of them with long flattened tails for steering and propulsion. They bore, in short, precisely the same relation to the other members of the class Reptilia which the Whales and Porpoises bear to the ordinary quadrupeds. Some of these animals are believed to have been fifty or sixty feet in length, thus rivalling the Whales, while others were of smaller dimensions, like the Porpoises and Dolphins. Some, like the _Ichthyosaurus_ and _Pliosaurus_ (Fig. 142_a_), were strongly built and powerful swimmers, and able to destroy the largest fishes, while others, like _Plesiosaurus_, had the body short and compact, the head small, and the neck long and flexible, and probably preyed on small animals near the borders of the waters. Catalogues of British fossils alone include about thirty species of Enaliosaurs, which haunted the coasts of Mesozoic Europe, a wonderful fact, when we consider the absence of these creatures from the modern seas, and the probability that only a fraction of the species are yet known to us.

Another remarkable group is that to which Cope has given the name of _Pythonomorpha_, and which he regards as allied to the serpents, or as gigantic sea-serpents provided with swimming paddles, but which Owen considers more nearly connected with the lizards. In either case they constitute a group by themselves, remarkable not only on account of their anatomical affinities with animals so unlike them in general port, but also for their enormously extended length and formidable dentition (Fig. 143). Such animals as the _Mososaurus_ of Maestricht and _Clidastes_ of Western America may have exceeded in length the largest Ichthyosaurs and the most bulky of living Cetaceans, though their slender forms and numerous vertebrA| remind one of the semi-fabulous sea-serpent, rather than of any known animal of our modern age. They were characteristic of the Later Mesozoic, more especially of the Cretaceous period, and must have been formidable enemies to the fishes of their time.

Owen has formed two orders[66] for the reception of some remarkable extinct reptiles of this age, found especially in South Africa and India, but also in Europe and America. The first includes large lizard-like animals having horny jaws like those of turtles, and in some of the species with great defensive tusks (Fig. 144). Their mode of life is not well known, but they may have been peaceable and harmless vegetable feeders. The second has been already referred to, in connection with the Permian, where it first appears, though it is continued in the Trias (Fig. 145). The resemblance of the skulls of these creatures to those of Carnivorous mammals is very striking, and nothing can be more singular than their early appearance and their decadence before the advent of those Tertiary mammals which in more modern times occupy their place.

_a_, One of the teeth. Natural size.]

Perhaps the most extraordinary of all the Mesozoic modifications of the reptilian type was that of the flying reptiles, or _Pterodactyls_. These were, in short, lizards modified for flight, somewhat in the same manner with the bats among the mammals. If the bat may be likened to a flying shrew-mouse, a Pterodactyl may in like manner be compared to a flying lizard; but the modification in the latter case is by much the more remarkable, inasmuch as the lizard is a cold-blooded animal, and far less likely to be endowed with the active circulation and muscular power necessary to flight than is the mouse. In point of fact, there can be no doubt that the Pterodactyls must have been provided with some approach to a mammalian or ornithic heart, as they certainly were with great breast-muscles attached to a keel in the breast-bone for working their large membranous wings. These wings were also somewhat original in their construction. They were not furnished with pinions, like those of the bird, but with a membrane like that of the bat, and this, instead of being stretched over four enormously lengthened fingers, as in that quadruped, was supported on a single elongated finger, corresponding, singularly enough, to the little finger, which usually inconspicuous member constituted in some of these strange creatures a limb longer than the whole body (Figs. 146, 147.) The other fingers of the hand were left free for walking or grasping. They are thus believed to have been able to walk as well as to fly, and even in case of need, to swim; while they could probably perch like birds on rocks and trees. Their heads, though very lightly framed, were large and reptilian in aspect, and furnished with sharp teeth, and sometimes probably with a beak as well. Few creatures of the old world are of more hideous and sinister aspect. Yet some of them must have been as light and graceful on the wing as swallows or sea-gulls. There are many species, most of them small, but some of those in the later Mesozoic attained to so great a size that the expanse of their wings must have exceeded twenty feet, making them veritable flying dragons, probably formidable to all the smaller animals of their time. Though these animals were strictly reptiles, they combined in their structures contrivances for aA"rial locomotion now distributed between the bats and the birds. They had bat-like wings and bird-like chests. Some had horny beaks. All had hollow limb bones, and air cavities to give lightness to the skull. Their brains approach to those of birds, and, as already stated, their respiration and circulation must have been of a high order. These facts are very suggestive, and perhaps in no point is the imagination or the faith of the devout evolutionist more severely tested than in realising the spontaneous assumption of these characters by reptiles, and their subsequent distribution between the very dissimilar types in which they are now continued.

The approximation of the winged reptiles to the birds is further increased by the facts that in the Jurassic and Cretaceous periods there were birds having reptilian tails and probably toothed jaws (_ArchA|opteryx macroura_, Fig. 148). The species just named, while in its limbs, trunk, and feathers a veritable perching bird, resembles a reptile in its head and tail. In the Cretaceous of Western America, Marsh has recently discovered two distinct types of toothed birds, one having the teeth in regular sockets, the other having them implanted in a groove in the jaw. One of these birds (_Ichthyornis dispar_, Fig. 149) was larger than a pigeon, with powerful wings constructed like those of ordinary birds. It had also the curious and old-fashioned peculiarity of biconcave vertebrA|, like those of fishes and some reptiles. Another (_Hesperornis regalis_) stood five or six feet high, and had rudimentary wings like those of the Penguins. These toothed birds extend into the Eocene Tertiary, where the _Odontopteryx_ of Owen has been known for some time. In the Eocene, however, this toothed bird is associated with others of ordinary types, allied closely to the Ostriches, the Pelicans, the Ibis, the Woodpeckers, the Hawks, the Owls, the Vultures, and the ordinary perching birds. In the Later Mesozoic, indeed, some reptiles became so bird-like that they nearly approached the earliest birds; but this was a final and futile effort of the reptile to obtain in the air that supremacy which it had long enjoyed in earth and water; and its failure was immediately succeeded in the Eocene by the appearance of a cloud of true birds, representing all the existing orders of the class.

_a_, Cross section of second tooth, natural size. _b_, Fifth tooth, natural size.]

We may close our notice of the winged reptiles of the Mesozoic by quoting from Phillips his summary of the characters of _Rhamphorhyncus_ (Fig. 147)[67]: aEurooeGifted with ample means of flight, able at least to perch on rocks and scuffle along the shore, perhaps competent to dive, though not so well as a palmiped bird, many fishes must have yielded to the cruel beak and sharp teeth of the _Rhamphorhyncus_. If we ask to which of the many families of birds the analogy of structure and probable way of life would lead us to assimilate _Rhamphorhyncus_, the answer must point to the swimming races, with long wings, clawed feet, hooked beak, and habits of violence and voracity; and for preference, the shortness of the legs and other circumstances may be held to claim for the Stonesfield fossil a more than fanciful similitude to the groups of Cormorants and other marine divers which constitute an effective part of the picturesque army of robbers of the sea.aEuroŁ

Lastly, the reptiles, in this age of their imperial sway, culminated in the _Dinosaurians_, animals far above any modern Reptilia in the perfection of their organisation, and many of them of gigantic size. Just as the Pterosaurs filled the place now occupied by the birds, so the Dinosaurs filled that represented by the mammals, or rather they took up a place holding some close relations with both the birds and the mammals. There were thus reptilian animals which on the one hand were the elephants and lions of their time, and on the other bore a grotesque resemblance to creatures so unlike these as the Ostriches, in so far as their anatomical structure was concerned; while it is evident that their whole organisation places them in the highest position possible within the reptilian class. Some of them must have been herbivorous, and probably slow in movement and quiet in nature. Others were carnivorous and of terrible energy, while furnished with the most destructive weapons (Figs. 152, 153). Many had the power of erecting themselves on their hind-feet and walking as bipeds; and to adapt them to this end their hinder limbs were very large and strong, and they had long pillar-like tails, while their fore-feet were comparatively small, and used perhaps mainly for prehension (Figs. 151, 154).

The size of some of these creatures was stupendous. The _Hadrosaurus_ of New Jersey, an Herbivorous species (Fig. 151), when erected on its hind limbs and tail, must have stood more than twenty feet in height. _Megalosaurus_ and _Iguanodon_, of the English Jurassic and Wealden, must have been of still more gigantic size. The former was a carnivorous animal, its head (Fig. 152) four or five feet in length, armed with teeth, sabre-shaped, sharp and crenate on the edges (Fig. 153), its hind limbs of enormous power, so that if our imagination does not fail us in the attempt to realise such a wonder, we may even suppose this huge animal, much larger than the largest elephant, springing like a tiger on its prey, a miracle of terrible strength and ferocity, before which no living thing could stand. Its companion, _Iguanodon_, was, on the contrary, a harmless herbivorous creature, using its great strength and stature as a means of obtaining leaves and fruits for food, and perhaps falling a prey to the larger Carnivorous Dinosaurs its contemporaries. A still more bulky animal was the _Ceteosaurus_, so admirably described by Phillips. Its thigh-bone measures more than five feet in length and a foot in diameter; and it must have stood ten feet high when on all fours, while its length must have reached forty or fifty feet. It seems from the forms of its bones to have been able to walk on land, but probably spent most of its time in the water, where it may be compared to a huge reptilian hippopotamus. Very recently some bones found in rocks, possibly of Wealden age, in Western America, and described by Cope and by Marsh, indicate that even _Ceteosaurus_ had not attained to the maximum of Dinosaurian dimensions. These new animals have vertebrA| twenty inches in length and from twelve inches to thirteen inches in the diameter of their bodies, while their lateral processes stretched three and a half feet. The shoulder-blade of one species is five feet in length, and its thigh-bone is six feet long. From these measurements Cope concludes that, unlike most other Dinosaurs, it had the fore-feet larger in proportion than the hind-feet, so as to have somewhat the appearance of a large giraffe. The bones of the back have a remarkable cavernous structure, which Cope interprets as indicating air cavities, to give lightness, as in the case of the bones of birds; but Owen suggests that the cavities were filled with cartilage, and that the animals were aquatic in their habits. Evidently in point of size the Dinosaurs had a better claim than even Behemoth to be called the aEurooechief of the ways of God.aEuroŁ Some of them, however, were of small size, and probably active and bird-like in their movements. One of these is the animal represented in Fig. 154, a species from the lithographic limestone of Solenhofen.[68]

_a_, Cross section. _b_, Crenellation of edges. Enlarged.]

Nothing in the life of the Mesozoic has so seized on the imagination of evolutionists as the links of connection between birds and reptiles, which has even been introduced by Huxley into the classification of animals, by his grouping these heretofore very distinct classes in one gigantic and comprehensive class of _Sauropsida_. It is necessary, therefore, to glance at these connections, and if possible to arrive at some conception of their true value. The links which connect the reptiles and the birds are twofold. First, that between the Dinosaurs and the ostrich tribe,[69] and, secondly, that between the Pterodactyls and their allies, and the peculiar Mesozoic birds, such as _ArchA|opteryx_. The first would serve to account for the few exceptional Struthious birds of the modern world. The second would account for the Passerine and other more ordinary birds; and thus, according to evolution, the now somewhat homogeneous class of birds would have a double, or more probably multiple, origin from several lines of reptilian ancestors. This, no doubt, greatly complicates the links of connection, whether these be supposed to indicate derivation or not.

If we inquire as to the first connection above stated, we may define it briefly in the words of Prof. Phillips, with reference to _Megalosaurus_, which aEurooewas not a ground-crawler, like the alligator, but moving with free steps, chiefly, if not solely, on the hind limbs, and claiming a curious analogy, if not some degree of affinity, with the ostrich.aEuroŁ[70] But the question arises, Was this resemblance merely that of two oviparous bipeds, or anything more? and when we set off, against the resemblance in haunch bones and hind limbs, the entire dissimilarity in head, in fore limbs, in vertebrA|, in tail, and probably in external covering, we are disposed to agree with Huxley in his statement, with respect to the Struthious birds, that their aEurooetotal amount of approximation to the reptilian type is but small; and the gap between reptiles and birds is but very slightly narrowed by their existence.aEuroŁ There is therefore here a great gap, even in the linking together of the types, independently of any question of derivation.

The second line of connection appears at first sight more promising. _ArchA|opteryx_ has a reptilian tail, and claws on the wing; and, as it had toothed jaws, like some of the birds in the Cretaceous, must have altogether made a much nearer approach to a reptile than any modern bird does. The remarkable aEurooefish-birdaEuroŁ (_Ichthyornis_) of Marsh is also very reptilian in some of its characters. But when we compare these reptilian birds with the Pterodactyls and their allies, a vast gap at once becomes apparent. Disregarding the external clothing, we find the wing in the two groups entirely dissimilar in details of construction, and this dissimilarity extends to the hind limbs as well, so that the Pterodactyls resemble bats rather than birds.

Without committing ourselves to any doctrine of development, we might have rejoiced if our geological discoveries had established a continuous chain, or two continuous chains, of being between the reptiles and the birds; but this end is evidently still far from being attained, though some approximation has undoubtedly been made. To quote again the admission of Huxley: aEurooeBirds are no more modified reptiles than reptiles are modified birds, the reptilian and ornithic types being both in reality somewhat different superstructures, raised upon one and the same ground-planaEuroŁaEuro"that ground-plan being the idea of the air-breathing oviparous vertebrate, and the reptile representing the less specialized and less ornate building. As yet the origin of that idea, and the mode of carrying it out to completion, remain unknown, except to the Architect and Builder, who may reveal them to earnest seekers for truth in His own good time.

As to links of connection with the Mammalia, these are still more obscure. In the Mesozoic the mammals are represented as yet only by a few small species allied to the pouched (Marsupial) and insectivorous quadrupeds of Australia, and these are closely linked with some of the smaller carnivorous Mammalia of the early Tertiary; but neither approach very closely to any known reptilian types. Nor have we yet any connecting links between the great marine reptiles and the Cetaceans and Sirenians which in the Tertiary take their place in the sea.

It is an interesting fact, to come before us in our next chapter, that the great land reptiles of the Mesozoic survived long enough to become contemporary with the introduction and first luxuriance of the modern types of vegetation in the later Cretaceous. It would be natural to suppose that access to these great supplies of better food would have stimulated the increase and development of the herbivorous species, and would have indirectly had the same effect on those that were carnivorous; but the opposite result seems to have followed, and in the next period the reptiles altogether gave place to the mammals, unless, indeed, they were themselves by some mysterious and comparatively rapid process transformed into Mammalia, to suit them to the better conditions of an improved world.

So far as yet known, the reign of reptiles was world-wide in its time; and the imagination is taxed to conceive of a state of things in which the seas swarmed with great reptiles on every coast, when the land was trodden by colossal reptilian bipeds and quadrupeds, in comparison with some of which our elephants are pygmies, and when the air was filled with the grotesque and formidable Pterodactyls. Yet this is no fancy picture. It represents a time which actually existed, when that comparatively low, brutal, and insensate type of existence represented by the modern crocodiles and alligators was supreme in the world. The duration of these creatures was long, and in watching the progress of creation, they would have seemed the permanent inhabitants of the earth. Yet all have perished, and their modern successors, except a few large species existing in the warmer climates, have become subject to the more recently introduced Mammalia.

How did the ancient reptile aristocracy perish? We are ignorant of the details of the catastrophe, but their final disappearance and replacement by the more modern fauna was connected with a great continental subsidence in the Cretaceous age, and with changes of climate and conditions preceding and subsequent to it. Yet the struggle for continued dominion was hard and protracted; and toward its close some of the champions of the reign of reptiles were the greatest and most magnificent examples of the type; as if they had risen in their might to defy approaching ruin. Thus some of the most stupendous forms appear in the later Cretaceous, after the great subsidence had made progress and almost attained its consummation. Like the antediluvian giants, they were undismayed even when the land began to sink beneath their feet; and for them there was no ark of deliverance.

_a_, _Aralia Saporteana_. _b_, _Sassafras araliopsis_. _c_, _Quercus primordialis_. _d_, _Fagus polyclada_. _e_, _Salix proteA|folia_. _f_, _Laurus proteA|folia_.]