Trechnotheria
Trechnotheria is a group of mammals that includes the therians and some fossil mammals from the Mesozoic Era. It includes both the extinct symmetrodonts and the living Cladotheria.
| Trechnotherians Temporal range: Early Jurassic - Holocene, | |
|---|---|
 | |
| Fossil of Zhangheotherium, a symmetrodont | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Clade: | Theriiformes |
| Clade: | Trechnotheria McKenna, 1975 |
| Subgroups[1] | |
Trechnotheria has been assigned various ranks, but was originally described as a "superlegion" by the naming authority.[2] A later node-based definition for Trechnotheria was 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.[1]
Phylogeny
A cladogram based on Luo, Cifelli & Kielan-Jaworowska, 2001, Luo, Kielan-Jaworowska & Cifelli, 2002 and, Kielan-Jaworowska, Cifelli & Luo, 2004.[4]
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- Unassigned Trechnotheria:
- †Austrotriconodon mckennai Bonaparte 1986 {Austrotriconodontidae Bonaparte 1990}
- †Chaoyangodens lii Hou & Meng 2014
- Paraphyletic Symmetrodonta Simpson 1925
- †Atlasodon monbaroni Sigogneau-Russell 1991 [Dryolestida, or Zatheria indet., milk tooth (Averianov, 2002)]
- †Kennetheredium leesi Sigogneau-Russell 2003a
- †Kotatherium haldanei Datta 1981
- †Trishulotherium kotaensis Yadagiri 1985
- Unassigned Cladotheria:
- †Afriquiamus nesovi Sigogneau-Russell 1999
- †Butlerigale Kühne 1968
- †Chunnelodon alopekodes Ensom & Sigogneau-Russell 1998
- †Guimarota freyi Kuhne 1968
- Unassigned Zatheria:
- †Arguimus khoshajari Dashzeveg 1979 [Arguitherium cromptoni Dashzeveg 1994] {Arguimuridae Dashzeveg 1994 [Arguitheriidae Dashzeveg 1994]}
- †Minimus richardfoxi Sigogneau-Russell 1999
- †Magnimus ensomi Sigogneau-Russell 1999
- †Mozomus shikamai Li et al. 2005 {Mozomuridae Li et al. 2005}
- †Nanolestes Martin 2002
- †N. drescherae Martin 2002
- †N. krusati Martin 2002
- †N. mackennai Martin, Averianov & Pfretzschner 2010
- Unassigned Boreosphenida:
- †Argaliatherium robustum Cifelli & Davis 2015
- †Carinalestes murensis Cifelli & Davis 2015
- †Hypomylos Sigogneau-Russell 1992
- †H. phelizoni Sigogneau-Russell 1992
- †H. micros Sigogneau-Russell 1994
- †Picopsidae Fox 1980
- †Picopsis pattersoni Fox 1980
- †Tirotherium aptum Montellano-Ballesteros & Fox 2015
Sources
- Luo, Z.−X.; Kielan−Jaworowska, Z.; Cifelli, R.L (2002). "In quest for a phylogeny of Mesozoic mammals" (PDF). Acta Palaeontologica Polonica. 47 (1): 1–78.
- McKenna, Malcolm C.; Bell, Susan K. (1997). Classification of Mammals: Above the Species Level. Columbia University Press. p. 43. ISBN 978-0-231-52853-5.
- Kielan-Jaworowska, Zofia; Cifelli, Richard; Luo Zhe-Xi (5 February 2005). Mammals from the age of dinosaurs: origins, evolution, and structure. Columbia University Press. p. 366. ISBN 978-0-231-11918-4.
- Haaramo, Mikko. "Holotheria – holotheres". Mikko's Phylogeny Archive.
See also
