VIII.A new stage is reached in Mastodon progress in spite of the apparent confusion of Long-jawed Trilophodons and Tetralophodons, Beak-jaws and Dibelodons. The trunk as an independent instrument is an undisputed fact as are also the short lower jaws. Lower tusks have disappeared or become rudimentary, and the superior ones tend to round section and upward curvature. So much for tusks and jaws and now for the molar teeth. Here we find something new, and of persistent type which places the animal in a distinctive class.
The Pig-Toothed Mastodon
His jaws were short of course, and his upper tusks were round and elephant-like, also his lower ones were vestigal or absent. In his molar teeth, however, the cones instead of being placed opposite each other to form ridges, zigzagged or alternated first on one side, then on the other. The old transverse-ridged pattern was further obscured by trefoils and small accessory cones, all of which tended to obliterate the valleys and form a pig-like tooth. "Pig-tooth" is an apt name for this Short-jawed Mastodon.
His first appearance is recorded in the early Pliocene of India (Mastodon Hasnoti) and Greece (Mastodon Pentelici), then through the middle Pliocene of India (Mastodon Sivalensis) into the late Pliocene of western Europe (Mastodon Arvernensis). The big upper tusks were as a rule long and straight but in the American species from Nebraska (Mastodon Mirificus), they curved outward and upward in the manner most familiar to us. In fact the Short-jawed Mastodon appeared quite up to date and might easily have been mistaken for a genuine elephant, provided some well-informed person did not look into his mouth and examine his molars too closely. These would have betrayed him as a Pig-tooth and not a true elephant, nor even a true mastodon.
Southern Asia was the great center of mastodon activity, particularly the Sind region of northern India, the Siwaliks Hills or southern face of the Himalayas, and central Burma. Here are tremendous deposits nearly 15,000 feet thick and all laid down in Miocene and Pliocene times. China, Japan and other Asiatic countries contributed, but northern India did most in Mastodon development. The strata of the Siwaliks are like the leaves of an old book, where one may read the story of the primitive elephant. In the bottom layers or first pages we recognize Dinotherium of Miocene days. Above him lie the scattered remnants of mastodons in their long-jawed, short-jawed, two and four tusked, three and four tooth-ridged and Pig-tooth stages. The Pliocene was the last-named's period of culmination and glory. The race spread out in endless variety and numbers, wandering eastward through Asia, northeastward into North America and westward through northern Africa and up into Europe. Climate offered no hindrance; cold, hot, wet and dry; it was all the same to them. They climbed over mountains two miles high, swam broad rivers, and battered their onward way through seemingly impenetrable forests. Food and water were the only essentials; they took the rest, good and bad, and adapted themselves to endless discouragements without complaint. It may be thought that they were wise and brave. They may have been to a degree, but no doubt they more often betrayed stupidity and took fright on small provocation. Not wisdom and courage but patience and adaptibility were their cardinal virtues. They did what they set out to do and kept at it, overcoming difficulties that would have appalled most other animals. They grew hair in cold weather and shed it in warm. In short, for patience and adaptibility the Mastodon was in a class by himself.
He had enemies - all animals had - but few of them could withstand his tremendous strength and energy. There was one, however, who caused him many sleepless nights and called for the best he had in him. This was the Sabre-toothed Tiger (Machaerodus [also Smilodon - GL,III]); not a real tiger, but a burly feline who bad given up the qualities of grace and swiftness to make of himself a perfect fighting machine. He was big-boned and heavily-muscled, and his two upper canine teeth were prolonged into sharp curved daggers, six or more inches long. With such weapons and the power to use them, the Sabre-tooth was a terror to big slow-moving animals, regardless of their size and strength, and no doubt many a mastodon was stabbed to death or "lived to fight another day" by taking to his heels.
But the Sabre-tooth probably played only a minor part in the disappearance of the "Pig-tooth" as well as other aberrant Mastodon races. Profound changes in climate and land-levels was more nearly the cause which led to their final extinction. They passed away as the Pleistocene period opened, leaving no known descendants, and by this time the world had seen the last of Long-jawed and Enamelled-tusked as well as Pig-toothed Mastodons.
[from the original, typewritten draft with hand-written corrections - GL,III, ed.]