. The age of mammals in Europe, Asia and North America. Mammals, Fossil; Paleontology. INTRODUCTION 11 parison of the molar teeth of nearly all mammals, and similar names can be given to the cusps in the upper and lower molar teeth respectively. This tritubercular molar owed its survival to three features: (1) the original advantage of its triangular form as expressed in the term "trigo- nodont" proposed by Riitimeyer; (2) the possibility of free addition of. Fig. 2. — Types of superior molar or grinding teeth. ^4. Bunodont, all conic, Hyra- cothcrium. B. Selenodont, all crescentic,
. The age of mammals in Europe, Asia and North America. Mammals, Fossil; Paleontology. INTRODUCTION 11 parison of the molar teeth of nearly all mammals, and similar names can be given to the cusps in the upper and lower molar teeth respectively. This tritubercular molar owed its survival to three features: (1) the original advantage of its triangular form as expressed in the term "trigo- nodont" proposed by Riitimeyer; (2) the possibility of free addition of. Fig. 2. — Types of superior molar or grinding teeth. ^4. Bunodont, all conic, Hyra- cothcrium. B. Selenodont, all crescentic, Protoceras. C. Lophodont, all crested, Rhinoceros. D. Buno-selenodont, conic-crescentic, . Paloeosyops. E. Lopho-buuodont, crested-conic, Tapirus. F. Lopho-seienodont, crested-crescentic, Anchitherium. new cusps as worked out in detail by Cope, Osborn, Scott, Wortman, Schlosser, and others; and (3) the wonderful independent modeling of these cusps either singly or in pairs into different forms, some remaining rounded, or bunoid, others becoming elongate, crested, or lophoid, others becoming crescentic or selenoid, as show^l in the accompanying figures (Fig. 2). Taking the Greek derivatives /Sowo's (hillock), Xoos (crest), o-tXijvr} (moon, crescent), and joining them with the word oSoSs (tooth), we have very simple names for the various types of teeth in which all the tubercles passed through the same form. These teeth may be either buno- dont, lophodont, or selenodont. There is a marvelous, independent, adaptive evolution of each cusp; one cusp may remain rounded while its neighbors become crescentic, and we thus find compound patterns, which may be given the somewhat cacophonous terms "bunoselenodont," or in the case of the conic-crested form, "; _ .,, „ ^ , . , . • ' ' Fig. 3. —Skull of the rat, showing Diprotodonty, or the enlargement of a extreme diprotodonty of the upper pair of cutting teeth, is an adaptation which and lower
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectpaleontology, bookyea
