Left lower jaw of Shuotherium dongi, from Kielan-Jaworowska et al. (2002).

Belongs within: Cynodontia.
Contains: Mammalia.

The Mammaliaformes has been defined as the most exclusive group containing both crown mammals and Sinoconodon, and represents the broader group of animals generally considered as 'mammals'. Sinoconodon rigneyi is known from a partial skull from the lower Jurassic of China.

Synapomorphies (from Luo et al. 2002): Craniomandibular joint comprised of dentary condyle and squamosal glenoid; petrosal promontorium present; extensive development of a petrosal floor for the cavum epiptericum housing the trigeminal ganglion; separate tympanic aperture for prootic canal containing the prootic vein; fenestra vestibuli lacking thickened rim; hypoglossal foramen (cranial nerve XII) separated from the jugular foramen (cranial nerves IX, X, XI).

Mammaliaformes [Atheria, Eotheria, Triconodonta]
    |--Sinoconodon [Sinoconodontidae] KH14
    |    `--S. rigneyi JL06
    `--+--Adelobasileus cromptoni KH14, LA02
       `--+--Hadrocodium Luo, Crompton & Sun 2001 KH14, LCS01
          |    `--*H. wui Luo, Crompton & Sun 2001 LCS01
          `--+--Morganucodontidae [Morganucodonta] KH14
             |    |  i. s.: Brachyozostrodon LK-JC02
             |    |         Helvetiodon LK-JC02
             |    |         Wareolestes LK-JC02
             |    |         Indotherium LK-JC02
             |    |         Gondwanadon tapani LK-JC02, DDL04
             |    |         Indozostrodon LK-JC02
             |    |         Erythrotherium parringtoni LK-JC02, CJ78
             |    |         Eozostrodon Parrington 1941 D07
             |    |           `--E. parvus D07
             |    |--Megazostrodon Crompton & Jenkins 1968 RW12, A02
             |    |    `--M. rudnerae CJ78
             |    `--+--Dinnetherium Jenkins et al. 1983 RW12, CM99
             |       `--Morganucodon Kühne 1949 BW14, A02
             |            |--M. oehleri OB13 [=Eozostrodon oehleri CJ78]
             |            `--M. watsoni Kühne 1949 S05 [=Eozostrodon watsoni CJ78]
             `--+--Megaconus Zhou, Wu et al. 2013 BW14, ZW13
                |    `--*M. mammaliaformis Zhou, Wu et al. 2013 ZW13
                `--+--+--Mammalia KH14
                   |  `--+--Pseudotribos KH14
                   |     `--Shuotherium Chow & Rich 1982 LC07, K-JCL02 [Shuotheridia, Shuotheriidae, Yinotheria]
                   |          |--*S. dongi Chow & Rich 1982 K-JCL02
                   |          |--S. kermacki Sigogneau-Russell 1998 K-JCL02
                   |          `--S. shilongi Wang et al. 1998 K-JCL02
                   `--+--Woutersia Sigogneau-Russell 1983 JL06, A02 [Woutersiidae]
                      `--+--Tikitherium JL06
                         `--Docodonta JL06
                              |  i. s.: Peraiocynodon inexpectatus Simpson 1928 N10
                              |--+--Tashkumyrodon JL06
                              |  `--Tegotheriidae N10
                              |       |--Tegotherium JL06
                              |       `--Sibirotherium JL06
                              `--+--+--Borealestes JL06
                                 |  `--+--Docodon Marsh 1881 JL06, N10
                                 |     `--Haldanodon exspectatus BW14, OB13
                                 `--+--Dsungarodon JL06
                                    `--+--Castorocauda Ji, Luo et al. 2006 BW14, JL06
                                       |    `--*C. lutrasimilis Ji, Luo et al. 2006 JL06
                                       `--+--Simpsonodon JL06
                                          `--Krusatodon JL06

*Type species of generic name indicated


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

[BW14] Bi, S., Y. Wang, J. Guan, X. Sheng & J. Meng. 2014. Three new Jurassic euharamiyidan species reinforce early divergence of mammals. Nature 514: 579–584.

[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.

[CJ78] Crompton, A. W., & F. A. Jenkins Jr. 1978. Mesozoic mammals. In: Maglio, V. J., & H. B. S. Cooke (eds) Evolution of African Mammals pp. 46–55. Harvard University Press: Cambridge (Massachusetts).

[DDL04] Datta, P. M., D. P. Das & Z.-X. Luo. 2004. A Late Triassic dromatheriid (Synapsida: Cynodontia) from India. Annals of Carnegie Museum 73 (2): 12–24.

[D07] Dixon, D. 2007. The Complete Illustrated Encyclopedia of Dinosaurs & Prehistoric Creatures. Hermes House: London.

[JL06] Ji, Q., Z.-X. Luo, C.-X. Yuan & A. R. Tabrum. 2006. A swimming mammaliaform from the Middle Jurassic and ecomorphological diversification of early mammals. Science 311: 1123–1127.

[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.

[KH14] Krause, D. W., S. Hoffmann, J. R. Wible, E. C. Kirk, J. A. Schultz, W. von Koenigswald, J. R. Groenke, J. B. Rossie, P. M. O'Connor, E. R. Seiffert, E. R. Dumont, W. L. Holloway, R. R. Rogers, L. J. Rahantarisoa, A. D. Kemp & H. Andriamialison. 2014. First cranial remains of a gondwanatherian mammal reveal remarkable mosaicism. Nature 515: 512–517.

[LA02] Long, J., M. Archer, T. Flannery & S. Hand. 2002. Prehistoric Mammals of Australia and New Guinea: One Hundred Million Years of Evolution. University of New South Wales Press: Sydney.

[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.

[LCS01] Luo, Z.-X., A. W. Crompton & A.-L. Sun. 2001. A new mammaliaform from the Early Jurassic and evolution of mammalian characteristics. Science 292: 1535–1540.

[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.

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

[OB13] O'Leary, M. A., J. I. Bloch, J. J. Flynn, T. J. Gaudin, A. Giallombardo, N. P. Giannini, S. L. Goldberg, B. P. Kraatz, Z.-X. Luo, J. Meng, X. Ni, M. J. Novacek, F. A. Perini, Z. S. Randall, G. W. Rougier, E. J. Sargis, M. T. Silcox, N. B. Simmons, M. Spaulding, P. M. Velazco, M. Weksler, J. R. Wible & A. L. Cirranello. 2013. The placental mammal ancestor and the post-K–Pg radiation of placentals. Science 339: 662–667.

[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.

[S05] Säilä, L. K. 2005. A new species of the sphenodontian reptile Clevosaurus from the Lower Jurassic of south Wales. Palaeontology 48 (4): 817–831.

[ZW13] Zhou, C.-F., S. Wu, T. Martin & Z.-X. Luo. 2013. A Jurassic mammaliaform and the earliest mammalian evolutionary adaptations. Nature 500: 163–167.

Last updated: 24 August 2018.

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