Plesiosaur

“ His jaw is of awful size and strength, and according to the best-informed naturalists, it does not contain less than a hundred and eighty-two teeth.
The other was the mighty Plesiosaurus, a serpent with a cylindrical trunk, with a short stumpy tail, with fins like a bank of oars in a Roman galley.
Its whole body covered by a carapace or shell, and its neck, as flexible as that of a swan, rose more than thirty feet above the waves, a tower of animated flesh!
These animals attacked one another with inconceivable fury. ”

“ Cope erred in most of the distinctive characters that he assigned to the genus Elasmosaurus, but was correct in an important one,—the length of the neck. We shall see that in all the known species assigned to Elasmosaurus, of which this part of the skeleton is known, the neck is very long, and that all of its vertebræ, save the most posterior ones, are longer than broad. Cimoliasaurus is, therefore, a relatively short-necked plesiosaur, though not so short as in the genus Polycotylus. ”

“ It was with a specimen of an elasmosaur (E. snowii) that Mudge first noticed the occurrence of the peculiar siliceous pebbles which he described; and it was also with another, a large species yet unnamed, from the Benton Cretaceous, that the like specimens were found described by me in 1892. That this habit was not confined to this type of plesiosaur, however, is certain, since I have also observed it in different species of Polycotylus and Trinacromerum, both relatively short-necked and long-headed plesiosaurs. ”

“ The neck is more or less elongated, having about twenty vertebrae in the longest-necked forms; the body is moderately long, and broad, and the tail is relatively short. The vertebrae and ribs are quite like those of the plesiosaurs, that is, the vertebrae are gently concave at each end, and the dorsal ribs are attached by a single head to the transverse process high up on the arch; the cervical ribs are double-headed, precisely like those of the older plesiosaurs, one of the characters which insistently proves the relationships of the two groups. ”

“ The skin has lost its scales, and the front limbs are developed into powerful paddles, sometimes six feet in length. The neck is drawn out until, in some specimens, it is found to consist of seventy-six vertebrae: the longest neck in the animal world. It is now doubted, however, if the neck was very flexible, and, as the jaws were imperfectly joined, the common picture of the Plesiosaur darting its snake-like neck in all directions to seize its prey is probably wrong. It seems to have lived on small food, and been itself a rich diet to the larger carnivores. ”

“ Conjectural Restoration of the Skeleton of Plesiosaurus dolichodeirus. (Conybeare.)
⁠2. Skeleton of Plesiosaurus dolichodeirus, in the British Museum, from the Lias at Lyme Regis. (Scharf. Original.)
Plate 17. V. I. p. 158.
A nearly, entire and unique skeleton of Plesiosaurus dolichodeirus, 5 feet 7 inches long, from the Lias of Street, near Glastonbury. This skeleton forms part of the splendid series of fossil Saurians, purchased for the British Museum, from T. Hawkins, Esq. in 1834. See V. I. p. 162, and Note. (Hawkins.) ”

“ In the extreme elongation of the neck, Elasmosaurus exceeded all other vertebrated animals of the past or present, and was, if we assume a diphyletic origin of the short-necked forms, the most specialized of all plesiosaurs, since in no other genus do we know of any species having as many as fifty cervical vertebrae. ”

“ Fossil remains now in the British Museum, and in the museum of the Geological Society, fully bear out the dimensions exhibited by the restoration of the animal as seen basking on the shore between the two specimens of Long-necked Plesiosaurs. The head of this species is relatively larger in proportion to the trunk, than in the Ichthyosaurus communis or Ichthyosaurus tenuirostris: the lower jaw is remarkably massive and powerful, and projects backwards beyond the joint, as far as it does in the crocodile. ”

“ A plesiosaurus, or some other of the huge marine reptiles usually believed to be extinct, might certainly have produced the phenomena described, granting the possibility of one having survived to the present time. ”

“ The slender-jawed, gavial-like plesiosaurs have more numerous, but smaller teeth. The surface of the skull on each side behind, for the attachment of the muscles closing the mandibles, is of great extent; in some this surface is increased by a high, thin crest in the middle, as in strongly carnivorous animals, all of which give conclusive evidence of the powerful muscles used in biting and seizing. There is but one temporal opening on each side, as in the ichthyosaurs and the mosasaurs, whereas the crocodiles, thalattosaurs, phytosaurs, etc., have two. ”

“ Descended from quite a different stock, the Plesiosaurs adapted themselves to sea life in their own fashion. Instead of adopting the flowing lines of a fish, the body took on a form more like that of a turtle, while the lengthened neck gave rise to the description applied to him since that they had the "body of a turtle strung on a snake." At their longest their necks -240- had as many as seventy-six bones, or vertebræ, which is more than any other animal living or extinct ever possessed. A smaller order of crocodiles appeared and flourished for a time ”

“ Ascending from the lower orders, we trace a gradual advancement in structure and office, till we arrive at those whose functions are the most exalted: thus, the tin of the fish becomes the paddle of the reptile Plesiosaurus and Ichthyosaurus; the same organ is converted into the wing of the Pterodactyle, the bird and bat; it becomes the fore-foot, or paw, in quadrupeds that move upon the land, and attains its highest consummation in the arm and hand of rational man. ”

“ 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. ”

“ These diagrams of the plesiosaurus, the ichthyosaurus, the pterodactyle, give you a notion of some of these extinct reptiles. And here is a cast of the pterodactyle and bones of the ichthyosaurus and the plesiosaurus, just as fresh as if it had been recently dug up in a churchyard. Thus, in the reptile class, there are no less than half of the orders which are absolutely extinct. If we turn to the 'Amphibia', there was one extinct order, the Labyrinthodonts, typified by the large salamander-like beast shown in this diagram.
No order of fishes is known to be extinct. ”

“ Blaineville in 1835 gave to the plesiosaurs an ordinal rank under the class Ichthyosauria, and even the astute Owen in 1839 united them with the ichthyosaurs as a suborder of his Enaliosauria, or “sea-saurians.” He called them Sauropterygia, or “reptile-finned,” and these terms, Enaliosauria, Ichthyopterygia, and Sauropterygia, have long persisted in works on natural history because of the prestige of Owen’s name. As we shall see later, the plesiosaurs are really of remote kinship to the ichthyosaurs, and there is no such natural group as the Enaliosauria. ”

“ Hay tells us has increased in length from the beginning of their race by the simple elongation of the vertebrae, as in the giraffe, and never by the addition of vertebrae. We may then account it a rule that swimming animals with a long neck have a short tail, and those with a short tail have a long flexible neck. Even in the plesiosaurs there is some variation of the length of the tail in correlation with the neck. Short-tailed animals must necessarily propel themselves through the water by the aid of their legs, especially the hind legs. ”

“ Remains of two embryos were found years ago in England associated in such a way that it is reasonable to suppose they were unhatched young, though embryos have never yet been found associated with skeletons of adults, as have those of ichthyosaurs in numerous instances. Bones of young, often quite young, plesiosaurs, are frequently found in shallow water deposits, and if the young were actually born alive they must have swum freely in the open waters while yet of very tender age. Rather singularly, however, the remains of these young plesiosaurs always occur as isolated bones. ”

“ As is the case with both the ichthyosaurs and mosasaurs, skeletons of plesiosaurs have been discovered with nearly all their bones in their relative positions, and with impressions of skin and outlines of body made before decomposition. Though our knowledge of the external appearance of the plesiosaurs when alive is perhaps not as full as we could wish, it is sufficient to give us a fairly good conception of what the animals really were. ”

“ HERE were in the sea in very ancient times—long before the flood—two very large and wonderful reptiles. Of them we present striking illustrations. One of them has been named the Ichthyosaurus, which means Fish Reptile. Its head somewhat resembled that of the crocodile, except that the orbit was much larger, and had the nostril placed close to it, as in the whale, and not near the end of the snout. It had four paddles and a powerful tail, and was very active in its movements and a rapid swimmer.
The other huge reptile was the Plesiosaurus, the meaning of which is “Near to a Reptile.” ”

“ Plesiosaurus, plē-zi-o-saw′rus, n. the type or leading genus of a family (Plesiosauridæ) of fossil sea-reptiles, which are characteristic of the Mesozoic systems. [Gr. plēsios, near, sauros, lizard.]
Plethora, pleth′o-ra, n. excessive fullness of blood: over-fullness in any way.—adjs. Plethore′tic, Plethor′ic, -al, afflicted with plethora: superabundant: turgid.—adv. ”

“ Pectoral girdle (in part) and front paddles of Elasmosaurus (Plesiosauria) . After Riggs. sc, scapula; h, humerus; cor, coracoid; r, radius; u, ulna.
The scapula of the plesiosaurs (Figs. 102, 110) is peculiar in the development of a strong proscapular process projecting downward, forward, and inward, and often meeting its mate in a median symphysis, a character unique among vertebrates. The blade is short and small, of little service for muscular attachment, unlike the scapulae of tail-propelling aquatic reptiles. ”

“ Edward Newman advanced the opinion that the closest affinities of the latter would be found to be with the Enaliosauria, or marine lizards, whose [Pg 98] fossil remains are so abundant in the oolite and the lias. This view has also been taken by other writers, and emphatically by Mr. Gosse. Neither he nor Mr. Newman insist that the "great unknown" must be the Plesiosaurus itself. Mr. Gosse says, "I should not look for any species, scarcely even any genus, to be perpetuated from the oolitic period to the present. ”

“ Imagine one of these monstrous animals, a plesiosaurus, some sixteen or twenty feet long, 192with a small wedge-shaped crocodilian head, a long, arched, serpent-like neck, a short compact body, provided with four large and powerful paddles, almost developed into hands; an animal not covered with brilliant scales, but with a black slimy skin. ”

“ More than twenty species of long-necked sea-lizards are known to geologists.
Professor Owen, in his great work on British Fossil Reptiles, when describing the huge Plesiosaurus dolichodeirus from Dorset, suggests that the carcase of this monster, after it sank to the [59] bottom 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.” ”

“ More probably after their long life of millions of years they had grown old, as everything grows old, and had become so fixed and unplastic in their structure and habits that even slight causes were at last their undoing. When we shall have bridged over that still imperfectly known transition period between the great Age of Reptiles and the greater Age of Mammals we shall have learned more definitely some of the causes of the extraordinary revolution in vertebrate life that then occurred. The plesiosaurs went out with nearly all of their kind, the mosasaurs, the pterodactyls, the dinosaurs ”

“ Land reptiles abounded, including species of the pterodactyle of the preceding age—tortoises, trionyces, crocodilians—and the pliosaurus, a creature which appears to have formed a link between the plesiosaurus and the crocodile. We know of at least six species of the flying saurian, the pterodactyle, in this formation.
Now, for the first time, we find remains of insects, an order of animals not well calculated for fossil preservation, and which are therefore amongst the rarest of the animal tribes found in rocks, though they are the most numerous of all living families. ”

“ The remains of the fossil Alligator, known as the mosasaurus, are also here, together with the wealden lizard of Kent, which was about twenty-five feet in length, and part of Cuvier's wonderful fossil Flying Lizard, or sterodactylus, which is described as a reptile having mammalian characteristics, a bat's wings, enormous eyes, and a bird's neck. In the westerly cases of the room the visitor should notice the fossil sea lizards divided into two families—the Plesiosaurus, and the Ichthyosaurus. ”