t nomenclature

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The t-nomenclature is a nomenclature of the tooth cusps (= tubercles) on the upper molars , which is used in particular in old-world mice . It was introduced by Gerrit Smith Miller in 1912 . Miller assumed that the upper molars of the Old World mice originally had three rows with three cusps each, as can be seen on the first molar of young wood mice . He numbered the bumps inside out and front to back. He designated the cusps of the inner row as t1, t4 and t7, those of the middle row as t2, t5 and t8 and those of the outer row as t3, t6 and t9. Missing cusps, especially on the second and third molar, can be homologated by comparison . In contrast to the t-nomenclature, other nomenclatures such as that according to Cope and Osborn or that according to Vandebroek are intended to express homologies for all mammals .

Compare the t-nomenclature with other nomenclatures
  Location description t nomenclature Nomenclature according to Cope and Osborn Vandebroek nomenclature
anterior inner hump antero-lingual mesio-lingual t1 Protoconus Epicon
Humps between t1 and t2   t1 to    
anterior middle hump antero-medial mesial t2    
anterior outer hump antero-buccal mesio-labial t3    
central inner hump central-lingual central-lingual t4 Hypoconus Endocon
central middle hump central-medial central t5    
central outer hump centro-buccal centro-labial t6 Paraconus Eocon
posterior inner hump postero-lingual disto-lingual t7   Disto-Endocon
posterior middle hump postero-medial distal t8    
rear outer hump postero-buccal disto-labial t9 Metaconus Distocon
  1. ↑ Locations on the teeth are used inconsistently in the literature. For example, in most mammals, the sides of the teeth that point forward or backward are indicated as anterior and posterior, respectively. Anthropologists and primatologists, on the other hand, usually use the terms mesial and distal for the sides that point to the middle or to the end of the dental arch. A distinction can also be made between incisors and canines ( mesial and distal ) and molars ( anterior and posterior ). The inside is referred to as lingual and the outside as labial , with molars often also buccal . (Ungar, 2010, p. 11)

literature

  • Gerrit Smith Miller: Catalog of the Mammals of Western Europe (Europe Exclusive of Russia) in the Collection of the British Museum . British Museum (Natural History), London 1912, doi : 10.5962 / bhl.title.8830 .
  • Jochen Niethammer, Franz Krapp: Handbook of the mammals of Europe. Volume 1: Rodents I . Akademische Verlagsgesellschaft, Wiesbaden 1978, ISBN 3-400-00458-8 .
  • Peter S. Ungar: Mammal Teeth: Origin, Evolution, and Diversity . The Johns Hopkins University Press, Baltimore 2010, ISBN 978-0-8018-9668-2 .

Remarks

  1. ^ Niethammer and Krapp, 1978 (Fig. 54)
  2. ↑ a b Niethammer and Krapp, 1978 (p. 281)
  3. ↑ Miller, 1912 ( p. 801 )
  4. ^ Niethammer and Krapp, 1978 (Tab. 55)