The Beak-Jawed Ryncotherium
The first appearance of the Proboscidian family in North or South America is recorded in the middle Miocene deposits of Oregon, Montana and Colorado. Animal life of the United States was then very different from what is is to-day. Besides Hornless Rhinoceri (Aphelops), Three-toed Horses (Merychippus, Hypohippus), and Giant Bear Dogs (Amphicyon), were several varieties of Camels, among them, one with a giraffe-like neck (Alticamelus). Deer (Merycodus) 20 inches high, Peccaries (Thinohyus), Otters (Potamotherium) and Nose-horned Rodents (Epigaulus) represent a few more of our native western animals whose fossil bones are to be found in the "Deep River," "Flint Creek," "Mascall" and "Pawnee Creek," all middle Miocene formations. Among them were emigrants from other lands, one a short-legged, single-horned Rhinocers (Teleoceras) and another of much greater interest, our first elephant-like animal (Ryncotherium) the Beak-Jawed Mastodon.
This last-named was a long-jawed, four-tusker with trefoiled molar teeth. Very little is known about him except that his unexplained presence is first recorded (Ryncotherium Proavus) in the middle Miocene rocks of Pawnee Creek, Colorado. Another (Ryncotherium Brevidens), has been found at Deep River, Oregon and traces of others are recognized in the Pliocene of
Kansas and Pleistocene of Mexico. Although as yet unrecorded in any other country, nevertheless he is to be considered as a visitor rather than resident and his progenitors must be sought on the African-Asiatic continent, the accepted center of elephant radiation.
Ryncotherium is the most ancient of the primitive American mastodons. His name refers to the peculiar inflection of his chin. In general he resembled the Long-jawed Trilophodon, except for this latter peculiarity, which in a very general way is suggestive of the Dinotherium. The upper tusks were of oval cross-section. Lower as well as upper tusks were protected from abrasion by enamel bands. These peculiarities distinguish the Beak-jaw from other primitive mastodons. The four tusks faced with enamel strips made very effective instruments for war and food-getting. The third or last molar in the Mastodon jaw has the most cross-ridges and is the largest, but in the Ryncotherium, this tooth is no larger nor more complicated than the preceding molars. No doubt the beast used his tusks like a beak and depended less upon his rearmost grinders, thereby retarding their development. In this respect, he was peculiar. In general form he probably resembled the Long-jawed Trilophodon. Some day we may know more about him, but his bones and teeth are so rarely met with that his ancestry and habits are absolutely unknown.
When it is considered that this class of the Mastodon family is founded upon a few teeth and bone fragments, one may realize the difficulties that confront the palaeontologist or student of ancient animals who for the want of more complete evidence, must as a rule depend upon single bones or teeth in making his determinations. Mistakes are made, but the wonder is that there are not more of them. Some day, a skull of the Beak-jawed Mastodon may be discovered, and he will be given a definite status, but until then he must be considered as an aberrant long-jawed type which played little or no part in the direct line of mastodon development.
[from the original, typewritten draft with hand-written corrections - GL,III, ed.]