Lower jaw of Pediomys, from here.

Belongs within: Boreosphenida.
Contains: Marsupialia.

The Metatheria are a clade of mammals including the total group of modern marsupials and all fossil taxa more closely related to marsupials than to other mammals. The earliest metatherians are known from the early Late Cretaceous of Eurasia and North America though they only survived into the Cenozoic in South America and Australia.

Synapomorphies (from Bi et al. 2014, for Sulestes + Marsupialia): Posterior vertical shelf of masseteric fossa connected to dentary condyle as thin crest along angular margin of mandible; dentary condyle continuous with semicircular posterior margin of dentary, condyle facing up due to up-turning of posterior-most part of dentary; molar with cristid obliqua present, contact closest to lowest point of protocristid; mesiolingual vertical crest of paraconid on lower molars forming a keel; entoconid near height of hypoconid; paraconid, metaconid, and entoconid on lower molars aligned; functional talonid basin of lower molars as long as wide; hypoconid/protoconid height ratio between 40% and 60%; stylar cuspule “C” (near ectoflexus) present on penultimate upper molar; wear facets 5 and 6 differentiated on labial face of entoconid; five upper incisors present; upper anterior-most incisor anteriorly projecting, separated from following teeth by diastema; body of calcaneus mediolaterally compressed at level of posterior calcaneoastragalar facet; calcaneal tubercle ventrally curved; lacrimal foramen on facial side of lacrimal; optic foramen not separated from sphenorbital fissure; incisive foramina intermediate in size.

<==Metatheria [Boreometatheria, Marsupialiformes, Marsupicarnivora] VG09
|–Sulestes BW14
`–+–Marsasia LJ03
`–+–+–Kokopellia VG09
|  `–Asiatherium KH14
`–+–Albertatherium BW14
`–+–Anchistodelphys LJ03
`–+–Peradectia [Alphadelphia] CGW04
|    |  i. s.: Caroloameghiniidae CGW04
|    |–Peradectidae GH99
|    |    |–Kasserinotherium tunisiense Crochet 1986 GH99
|    |    |–Peradectes Matthew & Granger 1921 S35
|    |    |    |–*P. elegans Matthew & Granger 1921 S35
|    |    |    `–P. minor OB13
|    |    `–Alphadon [Alphadontidae] CGW04
|    |         |–A. halleyi G03
|    |         |–A. marshi Simpson 1927 FN03
|    |         `–A. perexiguus G03
|    |–+–Pariadens VG09
|    |  `–Didelphodon [Stagodontidae] LJ03
|    |       `–D. vorax Marsh 1889 FN03
|    `–Pediomys [Pediomyidae] LJ03
|         |–P. clemensi G03
|         |–P. elegans G03
|         |–P. hatcheri SBL05
|         |–P. krejcii G03
|         `–P. prokrejcii G03
`–Notometatheria [Ameridelphia, Sparassodonta] RWN98
|–+–Mayulestes [Mayulestidae] WR07
|  |    `–M. ferox WR07
|  `–+–Marsupialia VG09
|     `–+–Pucadelphidae CGW04
|        |    |–Pucadelphys andinus WR07
|        |    |–Incadelphys CGW04
|        |    `–Mizquedelphys CGW04
|        `–Andinodelphys LJ03
`–Borhyaenoidea M77
|  i. s.: Hondadelphys M77 [Hondadelphidae CGW04]
|–Thylacosmilus Riggs 1933 D07 [Thylacosmilidae M77]
|    |–T. ferox D07
|    `–T. lentis D07
`–+–Proborhyaenidae [Proborhyaeninae] CGW04
|    |–Arminiheringia auceta M77, S32
|    `–Proborhyaena M77
`–+–Hathliacynidae [Hathliacyninae] M77
|    |–Sipalocyon M77
|    |–Patene M77
|    |–Cladosictis Amighino 1887 M77, D07
|    |    |–C. bardus D07
|    |    |–C. centralis D07
|    |    `–C. patagonica D07
|    `–Allqokirus CGW05
`–Borhyaenidae RWN98
|  i. s.: Pharsophorus lacerans S32
|         Procladosictis M77
|–Prothylacynus [Prothylacyninae] M77
`–Borhyaeninae M77
|–Nemolestes M77
|–Angelocabrerus M77
`–Borhyaena Ameghino 1894 D07
|–B. excavata D07
|–B. macrodonta D07
`–B. tuberata S32

Metatheria incertae sedis:
Kiruwamaq Goin & Candela 2004 AH07
Arcantiodelphys Vullo, Gheerbrant et al. 2009 VG09
`–*A. marchandi Vullo, Gheerbrant et al. 2009 VG09
Dakotadens VG09
Iqualadelphis RWN98
Turgidodon LJ03
|–T. praesagus G03
|–T. rhaister G03
`–T. russelli G03
Iugomortiferum VG09
Adelodelphys VG09
Sinbadelphys VG09

*Type species of generic name indicated


[AH07] Asher, R. J., I. Horovitz, T. Martin & M. R. Sánchez-Villagra. 2007. Neither a rodent nor a platypus: a reexamination of Necrolestes patagoniensis Ameghino. American Museum Novitates 3546: 1–40.

[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.

[CGW04] Case, J. A., F. J. Goin & M. O. Woodbourne. 2004. “South American” marsupials from the Late Cretaceous of North America and the origin of marsupial cohorts. Journal of Mammalian Evolution 11 (3–4): 223–255.

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

[FN03] Fox, R. C., & B. G. Naylor. 2003. A Late Cretaceous taeniodont (Eutheria, Mammalia) from Alberta, Canada. Neues Jahrbuch für Geologie und Paläontologie—Abhandlungen 229 (3): 393–420.

[GH99] Gheerbrant, E., & J.-L. Hartenberger. 1999. Nouveau mammifère insectivore (?Lipotyphla, ?Erinaceomorpha) de l’Eocène inférieur de Chambi (Tunisie). Paläontologische Zeitschrift 73 (1–2): 143–156.

[G03] Gordon, C. L. 2003. A first look of estimating body size in dentally conservative marsupials. Journal of Mammalian Evolution 10 (1–2): 1–21.

[LJ03] Luo, Z.-X., Q. Ji, J. R. Wible & C.-X. Yuan. 2003. An Early Cretaceous tribosphenic mammal and metatherian evolution. Science 302: 1934–1940.

[M77] Marshall, L. G. 1977. Cladistic analysis of borhyaenoid, dasyuroid, didelphoid, and thylacinid (Marsupialia: Mammalia) affinity. Systematic Zoology 26 (4): 410–425.

[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.

[RWN98] Rougier, G. W., J. R. Wible & M. J. Novacek. 1998. Implications of Deltatheridium specimens for early marsupial history. Nature 396: 459–463.

[S32] Simpson, G. G. 1932. Skulls and brains of some mammals from the Notostylops beds of Patagonia. American Museum Novitates 578: 1–11.

[S35] Simpson, G. G. 1935. The Tiffany fauna, Upper Paleocene. I.—Multituberculata, Marsupialia, Insectivora, and ?Chiroptera. American Museum Novitates 795: 1–19.

[SBL05] Sullivan, R. M., A. C. Boere & S. G Lucas. 2005. Redescription of the ceratopsid dinosaur Torosaurus utahensis (Gilmore, 1946) and a revision of the genus. Journal of Paleontology 79 (3): 564–582.

[VG09] Vullo, R., E. Gheerbrant, C. De Muizon & D. Néraudeau. 2009. The oldest modern therian mammal from Europe and its bearing on stem marsupial paleobiogeography. Proceedings of the National Academy of Sciences of the USA 106 (47): 19910–19915.

[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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