Trechnotheria

Trechnotherians; Temporal range: Late Triassic - Holocene, 216.5–0 Ma PreꞒ Ꞓ O S D C P T J K Pg N
	Kangaroo with her joey
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Clade:	Theriiformes
Clade:	Trechnotheria; McKenna, 1975
Subgroups
	†Spalacotheriida †Spalacotheriidae; †Zhangheotheriidae; ; Cladotheria †Dryolestida; Zatheria (including modern therians); ;

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.^[2]

Trechnotheria has been assigned various ranks, but was originally described as a "superlegion" by the naming authority.^[3] 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.^[4]

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.^[5]

†Gobiconodonta

†Amphilestidae

†Amphidontidae

†Eutriconodonta

Trechnotheria

†Spalacotheriida

Cladotheria

†Dryolestida

Zatheria

†Vincelestidae

†Amphitheriida

†Peramuridae

Boreosphenida

†Aegialodontia

†Pappotheriidae

Theria

	†

	Metatheria→Marsupialia

	Eutheria→Placentalia

Unassigned Trechnotheria:
- †Austrotriconodon mckennai Bonaparte 1986 {Austrotriconodontidae Bonaparte 1990}
- † Hou & Meng 2014
Paraphyletic Symmetrodonta Simpson 1925
- † Sigogneau-Russell 1991 [Dryolestida, or Zatheria indet., milk tooth (Averianov, 2002)]
- † Sigogneau-Russell 2003a
- † Datta 1981
- † Yadagiri 1985
Unassigned Cladotheria:
- † Sigogneau-Russell 1999
- † Kühne 1968
- †Chunnelodon alopekodes Ensom & Sigogneau-Russell 1998
- † Kuhne 1968
Unassigned Zatheria:
- † Dashzeveg 1979 [ Dashzeveg 1994] {Arguimuridae Dashzeveg 1994 [Arguitheriidae Dashzeveg 1994]}
- † Sigogneau-Russell 1999
- †Magnimus ensomi Sigogneau-Russell 1999
- † Li et al. 2005 {Mozomuridae Li et al. 2005}
- †Nanolestes Martin 2002
  - † Martin 2002
  - † Martin 2002
  - †N. mackennai Martin, Averianov & Pfretzschner 2010
Unassigned Boreosphenida:
- † Cifelli & Davis 2015
- † Cifelli & Davis 2015
- † Sigogneau-Russell 1992
  - † Sigogneau-Russell 1992
  - † Sigogneau-Russell 1994
- † Fox 1980
  - † Fox 1980
  - † Montellano-Ballesteros & Fox 2015

Sources[]

^ ^a ^b 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.CS1 maint: uses authors parameter (link)
^ "Trechnotheria - Mammalia". Paleobiology Database. Retrieved 2009-10-21.
^ McKenna, Malcolm C.; Bell, Susan K. (1997). Classification of Mammals: Above the Species Level. Columbia University Press. p. 43. ISBN 9780231528535.
^ 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.CS1 maint: uses authors parameter (link)
^ Haaramo, Mikko. "Holotheria – holotheres". Mikko's Phylogeny Archive.

[1]

Trechnotheria

Contents

Characteristics[]

Phylogeny[]

Sources[]

See also[]