Evolution of Mammalian Molar Teeth

Evolution of Mammalian Molar Teeth

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1907 edition. Excerpt: ...upper and lower molars when in contact of Pi rotwitt macrura (Cf. Fig. b'0). Compare the somewhat similar pattern of the molars in the Mole, and in Muogtde. several respects. First the mesostyle is doubled (wls1, wls2) permitting the formation of two complete triangles from the paracone, metacone, and styles of the upper molars. Second, the lower molar pattern consists As in other mammals without a talonid in the lower molars, the protocone is much elevated. The internal lodge (ring.) appears to correspond with that in Chrysochloris (Fig. 68).-ed. II of two triangles, the hinder one being formed from the enlarged talonid, the apices of these triangles being external and fitting in the spaces between successive outer triangles of the upper molars Flo. 61. Dentition of the Mannipial Mole, Noloryetra typhlopa. x. After E. C. Stirling. Thus, in conclusion, the various Marsupials afford the most convincing evidence of tritubercular origin. It is only necessary to understand the intermediate stages and to compare even the most highly specialized teeth with analogous types among the Placentals, to be convinced of the universal tritubercular derivation. Howes (Kept. Brit. Assoc., Belfast, 1902) declared he could not conceive the derivation of the Diprotodon molar from the tritubercular type, but comparison of these teeth with those of Afacropits and the stages leading to the Macropus type, together with the still stronger but more indirect evidence afforded by the Placentals1 indicates that the Diprotodon molar will ultimately be found to be of tritubercular origin. Fio. ti2. First upper molar of Nolaryetts typhbrps, upper figure, erown view; lower figure, anterior view, x. After E. C Stirling. SPECIA L REFERENCES. Dentition of Marsupials...show more

Product details

  • Paperback | 86 pages
  • 189 x 246 x 5mm | 168g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 123693198X
  • 9781236931986