Trechnotheria

Reconstruction of Necrolestes patagoniensis, by Gabriel L. Lio.


Belongs within: Mammalia.
Contains: Boreosphenida.

The Trechnotheria is defined as the most exclusive clade including Zhangheotherium and crown Theria, and are known from the late Jurassic. This clade is characterised by the development of a strong postvallum/prevallid shear between the upper and lower molars (Luo et al. 2002).

Synapomorphies (from Luo et al. 2002): Hypertrophied postvallum/prevallid shearing mechanism present, with acute triangulation of molar cusps; petrosal with large post-tympanic recess and caudal tympanic process; epitympanic recess bounded by lateral wall formed by squamosal. Scapula with posterior part of supraspinous fossa relatively expanded, far wider than glenoid region, fossa fan-shaped or triangular in outline; supraspinous fossa wider than infraspinous fossa. Proximo-lateral process of tibia vestigial or absent. Humerus with posterior aspect of distal articulation for radius cylindrical. Calcaneus with sustentacular facet oblique to the horizontal plane (uncertain in Spalacotherioidea).

<==Trechnotheria
    |--Spalacotheroidea [Spalacotheriinae] A02
    |    |  i. s.: Akidolestes LC07
    |    |         Heishanlestes MH06
    |    |--+--Maotherium LC07
    |    |  `--Zhangheotherium Hu et al. 1997 CM99
    |    |       `--Z. quinquecuspidens Hu et al. 1997 A02
    |    `--Spalacotheriidae A02
    |         |  i. s.: Shalbaatar Nessov 1997 A02
    |         |           `--S. bakht Nessov 1997 A02
    |         |--Spalacotherium Owen 1854 CM99 [incl. Peralestes Owen 1871 A02]
    |         `--Spalacolestinae CM99
    |              |--Spalacotheroides Patterson 1955 CM99
    |              |    `--S. bridwelli Patterson 1955 CM99
    |              `--+--Spalacotheridium Cifelli 1990 CM99
    |                 |    |--*S. mckennai Cifelli 1990 CM99
    |                 |    `--S. noblei Cifelli & Madsen 1999 CM99
    |                 `--+--Spalacolestes Cifelli & Madsen 1999 CM99
    |                    |    |--*S. cretulablatta Cifelli & Madsen 1999 CM99
    |                    |    `--S. inconcinnus Cifelli & Madsen 1999 CM99
    |                    `--Symmetrodontoides Fox 1976 CM99 [incl. Mictodon Fox 1984 A02]
    |                         |--*S. canadensis Fox 1976 CM99
    |                         |--S. foxi Cifelli & Madsen 1986 CM99
    |                         |--S. oligodontos Cifelli 1990 CM99
    |                         `--‘Mictodon’ symmetrodontoides Fox 1984 A02
    `--Cladotheria [Dryolestoidea, Pantotheria] LK-JC02
         |  i. s.: Thereuodon Sigogneau-Russell 1989 A02
         |         Atlasodon Sigogneau-Russell 1991 A02
         |--Dryolestida A02
         |    |  i. s.: Casamiquelia Bonaparte 1990 A02
         |    |         Bondesius Bonaparte 1990 [Bondesiidae] A02
         |    |--Henkelotherium Krebs 1991 RW12, CM99
         |    `--+--Dryolestes [Dryolestidae] RW12
         |       `--+--Comotherium RW12
         |          `--+--Amblotherium Owen 1871 RW12, CM99
         |             `--+--Laolestes Simpson 1927 RW12, CM99
         |                `--Groebertherium RW12
         `--+--+--Paurodontidae RAG11
            |  |    |  i. s.: Brancatherulum tendagurense Dietrich 1927 C78
            |  |    |--Foxraptor RW12
            |  |    `--+--Paurodon RAG11
            |  |       `--Drescheratherium RW12
            |  `--Meridiolestida RW12
            |       |  i. s.: Brandonia Bonaparte 1990 A02 [Brandoniidae RAG11]
            |       |         Barbereniidae RAG11
            |       |           |--Barberenia Bonaparte 1990 A02
            |       |           `--Quirogatherium Bonaparte 1990 A02
            |       |         Austrotriconodon [Austrotriconodontidae] RAG11
            |       |           |--A. mckennai RAG11
            |       |           `--A. sepulvedai RAG11
            |       |         Donodon Sigogneau-Russell 1991 A02 [Donodontidae RAG11]
            |       |           `--D. perscriptoris Sigogneau-Russell 1991 A02
            |       |--+--Leonardus cuspidatus RW12, RAG11
            |       |  `--+--Cronopio Rougier, Apesteguía & Gaetano 2011 RW12, RAG11
            |       |     |    `--*C. dentiacutus Rougier, Apesteguía & Gaetano 2011 RAG11
            |       |     `--Necrolestes RW12
            |       |          |--N. mirabilis Goin et al. 2007 RW12
            |       |          `--N. patagonensis Ameghino 1891 RW12
            |       `--Mesungulatoidea [Reigitheriidae] RAG11
            |            |--Reigitherium bunodontum Bonaparte 1990 RW12, N10
            |            `--+--Peligrotherium [Peligrotheriidae] RW12
            |               |    `--P. tropicalis RW12
            |               `--+--Mesungulatum RW12 [Mesungulatidae]
            |                  `--Coloniatherium silinskii RW12, RAG11
            `--Prototribosphenida [Peramura] LK-JC02
                 |--+--Peramus Owen 1871 RAG11, CM99
                 |  |    `--P. tenuirostris WR07
                 |  `--Amphitherium Blainville 1838 CM99 [Amphitheriidae RAG11]
                 `--+--Vincelestes [Vincelestidae] RAG11
                    |    `--V. neuquenianus WR07
                    `--Zatheria LK-JC02
                         |  i. s.: Arguitherium K-JCL02
                         |         Arguimus K-JCL02
                         |         Palaeoxonodon FP99
                         |--Microderson Sigogneau-Russell 1991 A02
                         |    `--*M. laaroussii Sigogneau-Russell 1991 CM99
                         `--+--Nanolestes Martin 2002 LC07, A02
                            |    |--N. drescherae WR07
                            |    `--N. krusati WR07
                            `--Boreosphenida LC07

*Type species of generic name indicated

REFERENCES

[A02] Averianov, A. O. 2002. Early Cretaceous “symmetrodont” mammal Gobiotheriodon from Mongolia and the classification of “Symmetrodonta”. Acta Palaeontologica Polonica 47 (4): 705-716.

[CM99] Cifelli, R. L., & S. K. Madsen. 1999. Spalacotheriid symmetrodonts (Mammalia) from the medial Cretaceous (upper Albian or lower Cenomanian) Mussentuchit local fauna, Cedar Mountain Formation, Utah, USA. Geodiversitas 21 (2): 167-214.

[C78] Cooke, H. B. S. 1978. Africa: the physical setting. In Evolution of African Mammals (V. J. Maglio & H. B. S. Cooke, eds) pp. 17-45. Harvard University Press: Cambridge (Massachusetts).

[FP99] Flynn, J. J., J. M. Parrish, B. Rakotosamimanana, W. F. Simpson & A. R. Wyss. 1999. A Middle Jurassic mammal from Madagascar. Nature 401: 57-60.

[K-JCL02] Kielan-Jaworowska, Z., R. L. Cifelli & Z.-X. Luo. 2002. Dentition and relationships of the Jurassic mammal Shuotherium. Acta Palaeontologica Polonica 47 (3): 479-486.

[LC07] Luo, Z.-X., P. Chen, G. Li & M. Chen. 2007. A new eutriconodont mammal and evolutionary development in early mammals. Nature 446: 288-293.

[LK-JC02] Luo, Z.-X., Z. Kielan-Jaworowska & R. L. Cifelli. 2002. In quest for a phylogeny of Mesozoic mammals. Acta Palaeontologica Polonica 47: 1-78.

[MH06] Meng, J., Y. Hu, Y. Wang, X. Wang & C. Li. 2006. A Mesozoic gliding mammal from northeast China. Nature 444 (7121): 889-893.

[N10] Naish, D. 2010. Tetrapod Zoology: Book One. CFZ Press: Bideford (UK).

[RAG11] Rougier, G. W., S. Apesteguía & L. C. Gaetano. 2011. Highly specialized mammalian skulls from the Late Cretaceous of South America. Nature 479: 98-102.

[RW12] Rougier, G. W., J. R. Wible, R. M. D. Beck & S. Apesteguía. 2012. The Miocene mammal Necrolestes demonstrates the survival of Mesozoic nontherian lineage into the late Cenozoic of South America. Proceedings of the National Academy of Sciences of the USA 109 (49): 20053-20058.

[WR07] Wible, J. R., G. W. Rougier, M. J. Novacek & R. J. Asher. 2007. Cretaceous eutherians and Laurasian origin for placental mammals near the K/T boundary. Nature 447: 1003-1006.

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