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Trechnotheria is a group of mammals that includes the therians and some fossil mammals from the Mesozoic Era. In the Jurassic through Cretaceous periods, the group was endemic to what would be Asia and Africa.[1]

Trechnotheria has been assigned various ranks, but was originally called a "superlegion" by the original author.[2] One reference has defined the Trechnotheria as the clade comprising the last common ancestor of Zhangheotherium and living therian mammals, and all its descendants.[3]

Characteristics

Like most Mesozoic mammal groups, early trechnotherians are known mainly from their teeth. Hence, one of the most prominent features of this group is the "hypertrophied postvallum/prevallid shearing mechanism", along with other dental characters. Features of the shoulder blade, tibia, humerus, and ankle joint also diagnose this clade.[4]

Phylogeny

A cladogram compiled by Mikko Haaramo and based on individual cladograms of after After Luo, Cifelli & Kielan-Jaworowska, 2001, Luo, Kielan-Jaworowska & Cifelli, 2002 and, Kielan-Jaworowska, Cifelli & Luo, 2004.[5]

Trechnotheria

Gobiconodonta




Amphilestidae




Amphidontidae




Eutriconodonta




Spalacotheriida


Cladotheria

Dryolestida


Zatheria

Vincelestidae




Amphitheriida



Peramuridae


Boreosphenida

Aegialodontia




Pappotheriidae


Theria

Protodelphia



MetatheriaMarsupialia



EutheriaPlacentalia













Sources

  1. ^ PaleoBiology Database: Trechnotheria, basic info "Trechnotheria - Mammalia" Check url= value (help). Paleobiology Database. Retrieved 2009-10-21. 
  2. ^ McKenna, Malcolm C., & Bell, Susan K. (2000). Classification of Mammals above the Species Level. University of Chicago Press. p. 43. 
  3. ^ Kielan-Jaworowska, Zofia; Cifelli, Richard; & Luo Zhe-Xi. Mammals from the age of dinosaurs: origins, evolution, and structure. Columbia University Press. p. 366. ISBN 978-0-231-11918-4. 
  4. ^ Luo, Z.−X., Kielan−Jaworowska, Z., and Cifelli, R.L. (2002). "In quest for a phylogeny of Mesozoic mammals" (PDF). Acta Palaeontologica Polonica. 47 (1): 1–78. 
  5. ^ Haaramo, Mikko. "Holotheria – holotheres". Mikko's Phylogeny Archive. 

See also


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