Trechnotheria

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Trechnotherians
Temporal range:
Ma
Fossil of
symmetrodont
Red fox, a modern-day trechnotherian
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Clade: Theriiformes
Clade: Trechnotheria
McKenna, 1975
Subgroups[1]

Trechnotheria is a group of mammals that includes the

symmetrodonts and the living Cladotheria
.

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]

Gobiconodonta

Amphilestidae

Amphidontidae

Eutriconodonta

Trechnotheria

Spalacotheriida

Cladotheria

Dryolestida

Zatheria

Vincelestidae

Amphitheriida

Peramuridae

Boreosphenida

Aegialodontia

Pappotheriidae

Theria

Protodelphia

Marsupialia

EutheriaPlacentalia

Sources

  1. ^ a b 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.
  2. ^ McKenna, Malcolm C.; Bell, Susan K. (1997). Classification of Mammals: Above the Species Level. Columbia University Press. p. 43. .
  3. ^ 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. .
  4. ^ Haaramo, Mikko. "Holotheria – holotheres". Mikko's Phylogeny Archive.

See also