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Shuotherium Temporal range: 167.3–148.4 Ma PreꞒ Ꞓ O S D C P T J K Pg N Middle Jurassic-Late Jurassic
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Synapsida
Clade:	Therapsida
Clade:	Cynodontia
Clade:	Mammaliaformes
Family:	†Shuotheriidae
Genus:	†Shuotherium Chow & Rich, 1982
Type species
†Shuotherium dongi Chow & Rich, 1982
Species
S. dongi Chow & Rich 1982 S. shilongi Wang, Clemens & Hu 1998

Shuotherium is a fossil mammaliaform known from Middle-Late Jurassic of the Forest Marble Formation of England, and the Shaximiao Formation of Sichuan, China.

The original holotype is composed of a partial dentary and seven teeth (two which are incomplete). The holotypes for other species of this genus are solely represented by isolated molars. Shuotherium, along with Pseudotribos has been placed in the family Shuotheriidae as a sister taxon of the Australosphenida (see, Yinotheria), making it a relative of modern monotremes. However, some studies place it and other shuothereres as closer to therian mammals, and another outside of Mammalia altogether.

Description

In the lower molars, the talonid is situated in front of the trigonid, such a unique dental form is distinct from the typical tribosphenic pattern. In this "pseudotribosphenic" trait, the mesial cingulid is expanded to form a pseudotalonid, and its distal talonid is underdeveloped. It shares with Australosphenida a thin, slender lower jaw but differs from the non-monotreme Ausktribosphenida by having more developed postdentary trough. Its dental formula has been reconstructed as: p4, m3 (four premolars, three molars).

Kielan-Jaworowska, Cifelli & Luo 2002 harvnb error: no target: CITEREFKielan-JaworowskaCifelliLuo2002 (help) had this to say regarding the fossil:

In our view, the most compelling evidence as to the affinities of Shuotherium lies in the structure of the last premolar, which shares striking similarities to that of Australosphenida

Lower molar structure of Shuotherium and Australosphenida is obviously quite different, and for this reason we do not place Shuotherium within this Gondwanan clade. Based on the limited evidence available, however, we suggest that Shuotherium is a viable sister-taxon to Australosphenida.

Notes

1. Sigogneau−Russell, D. 1998. Discovery of a Late Jurassic Chinese mammal in the upper Bathonian of England. Comptes Rendus de l’Académie des Sciences, Paris 327: 571–576
2. ^ M. Chow and T. H. V. Rich. 1982. Shuotherium dongi, n. gen. and sp., a therian with pseudo-tribosphenic molars from the Jurassic of Sichuan, China. Australian Mammalogy 54:127-142
3. ^ Kielan−Jaworowska, Z.; Cifelli, R.L.; Luo, Z.−X. (2002). "Dentition and relationships of the Jurassic mammal Shuotherium" (PDF). Acta Palaeontologica Polonica. 47 (3): 479–86
4. ^ Kielan-Jaworowska, Zofia; Cifelli, Richard L.; Luo, Zhe-Xi 2004. Mammals from the Age of Dinosaurs: Origins, Evolution, and Structure. New York: Columbia University Press. ISBN 9780231509275
5. Rougier, Guillermo W.; Martinelli, Agustín G.; Forasiepi, Analía M.; Novacek, Michael J., New Jurassic mammals from Patagonia, Argentina : a reappraisal of australosphenidan morphology and interrelationships; American Museum Novitates, no. 3566, 2007
6. Tom Rich, Patricia Vickers Rich, Palaeobiogeography of Mesozoic Mammals – Revisited, Article · January 2012 DOI: 10.1007/978-90-481-3428-1_32
7. Mao, Fangyuan; Li, Zhiyu; Wang, Zhili; Zhang, Chi; Rich, Thomas; Vickers-Rich, Patricia; Meng, Jin (2024-04-03). "Jurassic shuotheriids show earliest dental diversification of mammaliaforms". Nature. doi:10.1038/s41586-024-07258-7. ISSN 0028-0836.

References

• Chow, M.; Rich, T. H. (1982). "Shuotherium dongi, n. gen. and sp., a therian with pseudo-tribosphenic molars from the Jurassic of Sichuan, China". Australian Mammalogy. 5 (2): 127–42. doi:10.1071/AM82013. S2CID 254714864. Retrieved May 12, 2013.
• Dykes, Trevor. "Mesozoic Mammals: Shuotheriidae & Australosphenida, an internet directory". Archived from the original on July 16, 2012. Retrieved May 12, 2013.
• Kielan−Jaworowska, Z.; Cifelli, R.L.; Luo, Z.−X. (2002). "Dentition and relationships of the Jurassic mammal Shuotherium" (PDF). Acta Palaeontologica Polonica. 47 (3): 479–86. Retrieved May 12, 2013.
• Kielan-Jaworowska, Zofia; Cifelli, Richard L.; Luo, Zhe-Xi (2004). Mammals from the Age of Dinosaurs: Origins, Evolution, and Structure. New York: Columbia University Press. ISBN 9780231509275.
• Sigogneau-Russell, Denise (1998). "Discovery of a Late Jurassic Chinese mammal in the Upper Bathonian of England". Comptes Rendus de l'Académie des Sciences, Série IIA. 327 (8): 571–576. Bibcode:1998CRASE.327..571S. doi:10.1016/S1251-8050(99)80040-8. OCLC 4931582858.
• Wang, Yuanqing; Clemens, William A; Hu, Yaoming (1998). "A Probable Pseudo-Tribosphenic Upper Molar from the Late Jurassic of China and the Early Radiation of the Holotheria". Journal of Vertebrate Paleontology. 18 (4): 777–87. Bibcode:1998JVPal..18..777W. doi:10.1080/02724634.1998.10011106. JSTOR 4523955. OCLC 4899517409.

v t e Cynodontia
Kingdom: Animalia Phylum: Chordata Clade: Synapsida Clade: Therapsida Clade: Eutheriodontia Synapsida see Synapsida Cynodontia see below↓
Cynodontia Cynodontia †Dvinia †Nanocynodon †Madysaurus †Uralocynodon †Charassognathidae Abdalodon Charassognathus Nshimbodon †Procynosuchidae Procynosuchus Sludica Epicynodontia †Bolotridon †Cynosaurus †Nanictosaurus †Nythosaurus †Platycraniellus †Thrinaxodon †Vetusodon †Galesauridae Galesaurus Progalesaurus Eucynodontia †Kataigidodon †Cynognathia see Cynognathia Probainognathia see below↓
Probainognathia Probainognathia †Agudotherium †Candelariodon †Charruodon †Lumkuia †Protheriodon †Tessellatia †Chiniquodontidae Aleodon Chiniquodon Cromptodon? Riojanodon †Probainognathidae Bonacynodon Probainognathus †Ecteniniidae Diegocanis Ecteninion Trucidocynodon Prozostrodontia †Alemoatherium †Deccanodon †Dromatherium †Inditherium †Microconodon †Polonodon †Pseudotriconodon †Rewaconodon †Santacruzgnathus †Therioherpeton †Tricuspes †Prozostrodontidae Prozostrodon Pseudotherium †Tritheledontidae Chaliminia Diarthrognathus Elliotherium Irajatherium Pachygenelus Riograndia? Tritheledon Mammaliamorpha †Adelobasileus †Botucaraitherium †Brasilodon †Sinoconodon †Tikiodon †Tritylodontidae Bienotherium Bienotheroides Bocatherium Dianzhongia Dinnebitodon Fossiomanus Kayentatherium Lufengia Montirictus Nuurtherium Oligokyphus Polistodon Shartegodon Stereognathus Tritylodon Xenocretosuchus Yuanotherium Yunnanodon Mammaliaformes see below↓
Mammaliaformes Mammaliaformes †Bocaconodon †Brachyzostrodon †Bridetherium †Cherwellia †Cifellilestes †Delsatia †Dianoconodon †Dinnetherium †Dyskritodon †Eozostrodon †Erythrotherium †Gondwanadon †Hadrocodium †Hallautherium †Helvetiodon †Indotherium †Indozostrodon †Megazostrodon †Morganucodon †Paceyodon †Paikasigudodon †Purbeckodon †Rosierodon †Sinoconodon? †Storchodon †Stylidens †Wareolestes †Woutersia †Kuehneotheriidae Fluctuodon Kotatherium Kuehneon Kuehneotherium †Shuotheriidae Feredocodon Itatodon? Paritatodon? Pseudotribos Shuotherium †Docodonta Agilodocodon Borealestes Castorocauda Cyrtlatherium Dobunnodon Docodon Docofossor Dsungarodon Ergetiis Gondtherium? Haldanodon Hutegotherium Itatodon? Khorotherium Krusatodon Microdocodon Paritatodon? Peraiocynodon Sibirotherium Simpsonodon Tashkumyrodon Tegotherium †Haramiyida Avashishta? Hypsiprymnopsis? Haramiyavia Kalaallitkigun Kollikodon? Mojo? Theroteinus Thomasia Euharamiyida Allostaffia? Arboroharamiya Baidabatyr? Butlerodon Cryoharamiya Kermackodon? Maiopatagium Megaconus? Qishou Sharypovoia Shenshou Sineleutherus Vilevolodon Woodeatonia Xianshou Gondwanatheria? Hahnodontidae? Cifelliodon Denisodon Hahnodon Crown-Mammalia see Mammalia
See also Incertae sedis †Cistecynodon †Eoraetia †Gaumia †"Hahnia" †Kunminia †Lepagia †Meurthodon †Mitredon †Panchetocynodon †Redondagnathus †Saurodesmus? Paraphyletic / Polyphyletic groups Dromatheriidae Morganucodonta Symmetrodonta Triconodonta
Category

• Shuotheriidae
• Middle Jurassic synapsids of Asia
• Late Jurassic synapsids of Asia
• Middle Jurassic synapsids of Europe
• Fossil taxa described in 1982
• Taxa named by Zhou Mingzhen
• Taxa named by Tom Rich