Temporal range: Jurassic - Recent
File:Kangaroo and joey03.jpg
Kangaroo with her joey
Scientific classification Red Pencil Icon
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Infraclass: Holotheria
Superlegion: Trechnotheria
McKenna 1975

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 is a clade that includes symmetrodonts, Spalacotheriids, dryolestids and therians. This clade excludes monotremata. 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]


Like most Mesozoic mammal groups, early trechnotherians are known mainly from their teeth. Hence, one of 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]


  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. 

See also

Mammal Diversity 2011 This article is part of Project Mammal Taxonomy, a All Birds project that aims to write comprehensive articles on every order, family and other taxonomic rank related to mammals.
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