Like the "Fossil man" the sea-serpent flourishes perennially in the newspapers and, despite the fact that he is now mainly regarded as a joke, there have been many attempts to habilitate this mythical monster and place him on a foundation of firm fact. The most earnest of these was that of M. Oudemans, who expressed his belief in the existence of some rare and huge seal-like creature whose occasional appearance in southern waters gave rise to the best authenticated reports of the sea-serpent. Among other possibilities it has been suggested that some animal believed to be extinct had really lived over to the present day. Now there are a few waifs, spared from the wrecks of ancient faunas, stranded on the shores of the present, such as the Australian Ceratodus and the Gar Pikes of North America, and these and all other creatures that could be mustered in were used as proofs to sustain this theory. If, it was said, these animals have been spared, why not others? If a fish of such ancient lineage as the Gar Pike is so common as to be a nuisance, why may there not be a few Plesiosaurs or a Mosasaur somewhere in the depths of the ocean? The argument was a good one, the more that we may "suppose" almost anything, but it must be said that no trace of any of these creatures has so far been found outside of the strata in which they have long been known to occur, and all the probabilities are opposed to this theory. Still, if some of these creatures had been spared, they might well have passed for sea-serpents, even though Zeuglodon, the one most like a serpent in form, was the one most remotely related to snakes.
Zeuglodon, the yoke-tooth, so named from the shape of its great cutting teeth, was indeed a strange animal, and if we wonder at the Greenland Whale, whose head is one-third its total length, we may equally wonder at Zeuglodon, with four feet of head, ten feet of body, and forty feet of tail. No one, seeing the bones of the trunk and tail for the first time, would suspect that they belonged to the same animal, for while the vertebræ of the body are of moderate size, those of the tail are, for the bulk of creature, the longest known, measuring from fifteen to eighteen inches in length, and weighing in a fossil condition fifty to sixty pounds. In life, the animal was from fifty to seventy feet in length, and not more than six or eight feet through the deepest part of the body, while the tail was much less; the head was small and pointed, the jaws well armed with grasping and cutting teeth, and just back of the head was a pair of short paddles, not unlike those of a fur seal. It is curious to speculate on the habits of a creature in which the tail so obviously wagged the dog and whose articulations all point to great freedom of movement up and down. This may mean that it was an active diver, descending to great depths to prey upon squid, as the Sperm-Whale does to-day, while it seems quite certain that it must have reared at least a third of its great length out of water to take a comprehensive view of its surroundings. And if size is any indication of power, the great tail, which obviously ended in flukes like those of a whale, must have been capable of propelling the beast at a speed of twenty or thirty miles an hour. Something of the kind must have been needed in order that the small head might provide food enough for the great tail, and it has been suggested that inability to do this was the reason why Zeuglodon became extinct. On the other hand, it has been ingeniously argued that the huge tail served to store up fat when food was plenty, which was drawn upon when food became scarce. The fur seals do something similar to this, for the males come on shore in May rolling in blubber, and depart in September lean and hungry after a three months' fast.
Zeuglodons must have been very numerous in the old Gulf of Mexico, for bones are found abundantly through portions of our Southern States; it was also an inhabitant of the old seas of southern Europe, but, as we shall see, it gave place to the great fossil shark, and this in turn passed out of existence. Still, common though its bones may be, stories of their use for making stone walls—and these stories are still in circulation—resolve themselves on close scrutiny into the occasional use of a big vertebra to support the corner of a corn-crib.
The scientific name of Zeuglodon is Basilosaurus cetoides, the whale-like king lizard—the first of these names, Basilosaurus, having been given to it by the original describer, Dr. Harlan, who supposed the animal to have been a reptile. Now it is a primary rule of nomenclature that the first name given to an animal must stick and may not be changed, even by the act of a zoölogical congress, so Zeuglodon must, so far as its name is concerned, masquerade as a reptile for the rest of its paleontological life. This, however, really matters very little, because scientific names are simply verbal handles by which we may grasp animals to describe them, and Dr. Le Conte, to show how little there may be in a name, called a beetle Gyascutus. Owen's name of Zeuglodon, although not tenable as a scientific name, is too good to be wasted, and being readily remembered and easily pronounced may be used as a popular name.
Fig. 11.—Koch's Hydrarchus, Composed of Portions of the Skeleton of Several Zeuglodons.
One might think that a creature sixty or seventy feet long was amply long enough, but Dr. Albert Koch thought otherwise, and did with Zeuglodon as, later on, he did with the Mastodon, combining the vertebræ of several individuals until he had a monster 114 feet long! This he exhibited in Europe under the name of Hydrarchus, or water king, finally disposing of the composite creature to the Museum of Dresden, where it was promptly reduced to its proper dimensions. The natural make-up of Zeuglodon is sufficiently composite without any aid from man, for the head and paddles are not unlike those of a seal, the ribs are like those of a manatee, and the shoulder blades are precisely like those of a whale, while the vertebræ are different from those of any other animal, even its own cousin and lesser contemporary Dorudon. There were also tiny hind legs tucked away beneath skin, but these, as well as many other parts of the animal's structure were unknown, until Mr. Charles Schuchert collected a series of specimens for the National Museum, from which it was possible to restore the entire skeleton. Owing to a rather curious circumstance the first attempt at a restoration was at fault; among the bones originally obtained by Mr. Schuchert there were none from the last half of the tail, an old gully having cut off the hinder portion of the backbone and destroyed the vertebræ. Not far away, however, was a big lump of stone containing several vertebræ of just the right size, and these were used as models to complete the papier-maché skeleton shown at Atlanta, in 1894. But a year after Mr. Schuchert collected a series of vertebræ, beginning with the tip of the tail, and these showed conclusively that the first lot of tail vertebræ belonged to a creature still undescribed and one probably more like a whale than Zeuglodon himself, whose exact relationships are a little uncertain, as may be imagined from what was said of its structure. Mixed with the bones of Zeuglodon was the shell of a turtle, nearly three feet long, and part of the backbone of a great water-snake that must have been twenty-five feet long, both previously quite unknown. One more curious thing about Zeuglodon bones remains to be told, and then we are done with him; ordinarily a fossil bone will break indifferently in any direction, but the bones of Zeuglodon are built, like an onion, of concentric layers, and these have a great tendency to peel off during the preparation of a specimen.
And now, as the wheels of time and change rolled slowly on, sharks again came uppermost, and the warmer Eocene and Miocene oceans appear to have fairly teemed with these sea wolves. There were small sharks with slender teeth for catching little fishes, there were larger sharks with saw-like teeth for cutting slices out of larger fishes, and there were sharks that might almost have swallowed the biggest fish of to-day whole, sharks of a size the waters had never before contained, and fortunately do not contain now. We know these monsters mostly by their teeth, for their skeletons were cartilaginous, and this absence of their remains is probably the reason why these creatures are passed by while the adjectives huge, immense, enormous are lavished on the Mosasaurs and Plesiosaurs—animals that the great-toothed shark, Carcharodon megalodon, might well have eaten at a meal. For the gaping jaws of one of these sharks, with its hundreds of gleaming teeth must, at a moderate estimate, have measured not less than six feet across.