. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. Paraconid Protoconid B ., .. . , \ Paraconid ^Metacomd HâProtoconus Paraconus ^^feCjvir N/^^\â*â â/ ^Metaconus #Nf Clonic. / "T 7'- * Roots A^/~ " v Roots AJ w TRICONODON CANIS (DOG) Lower Upper Molar Molar SCHEMATIC DIAGRAM MICROCONODON Fig. 249. Plan of molar teeth. Anterior is to the left in each case. (After Osborn.) The addition of two such cusps gives rise to the tritubercular tooth which is the typical molar of mammals generally from the e
. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. Paraconid Protoconid B ., .. . , \ Paraconid ^Metacomd HâProtoconus Paraconus ^^feCjvir N/^^\â*â â/ ^Metaconus #Nf Clonic. / "T 7'- * Roots A^/~ " v Roots AJ w TRICONODON CANIS (DOG) Lower Upper Molar Molar SCHEMATIC DIAGRAM MICROCONODON Fig. 249. Plan of molar teeth. Anterior is to the left in each case. (After Osborn.) The addition of two such cusps gives rise to the tritubercular tooth which is the typical molar of mammals generally from the earliest repre- sentatives down to Eocene times. Even today the mole Chrysochloris and certain other insectivores, as well as the opossum Didelphys, and some lemurs, exhibit this ancestral tritubercular type, which is well adapted to the business of crushing insects. The three cusps of a tritubercular molar are arranged in the form of a triangle. Molars of the lower jaw have a more lateral cusp, the protoconid, medial to which are the two secondary cusps, the paraconid in the anterior position and the more posterior metaconid. The corresponding cusps on molars of the upper jaw are indicated by the terminationâus. Thus in a molar of the upper jaw there are a medial protoconus and two more lateral cusps, an anterior paraconus and a posterior metaconus. This means that the orientation of the triangle of cusps on the upper jaw is the mirror image. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Walter, Herbert Eugene, b. 1867; Sayles, Leonard Perkins, 1902-. New York : Macmillan Co.
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Keywords: ., bookcentury1900, booksubjectanatomycomparative, booksubjectverte
