Symmetrodonta

‎Classis: Mammalia
Cladus: Trechnotheria
Ordo: †Symmetrodonta
Familiae: (lato sensu): †Amphidontidae – †Bondesiidae – †Kuehneotheriidae – †Shuotheriidae – †Spalacotheriidae – †Tinodontidae – †Thereuodontidae – †Woutersiidae – †Zhangheotheriidae
Familiae: (stricto sensu): †Spalacotheriidae – †Zhangheotheriidae

"Symmetrodonta" Simpson, 1925: 560

Taxonomic note: phylogenetic analysis implied that "Symmetrodonta" is artificial (paraphyletic) with the symmetrodont molar pattern representing a structural grade that evolved multiple times. The name is still used informally by some researchers for convenience, in a descriptive sense, or restricted to the Spalacotheriidae and Zhangheotheriidae.

• Simpson, G.G. 1925. Mesozoic Mammalia, III: preliminary comparison of Jurassic mammals except multituberculates. American Journal of Science, series 5 10(60): 559–569.

• Averianov, A.O. 2002. Early Cretaceous “symmetrodont” mammal Gobiotheriodon from Mongolia and the classification of “Symmetrodonta”. Acta Palaeontologica Polonica 47(4): 705–716.
• Kielan-Jaworowska, Z., Cifelli, R.L. & Luo, Z.-X. 2004. Mammals from the Age of Dinosaurs: Origins, Evolution, and Structure. Columbia University Press, New York. 1–630 pp. ISBN 9780231119184 Reference page. 
• Meng, J., Hu, Y., Li, C. & Wang, Y. 2006. The mammal fauna in the Early Cretaceous Jehol Biota: implications for diversity and biology of Mesozoic mammals. Geological Journal 41(3–4): 439–463. DOI: 10.1002/gj.1054
• Averianov, A.O. & Lopatin, A.V. 2011. Phylogeny of Triconodonts and Symmetrodonts and the Origin of Extant Mammals. Doklady Biological Sciences 436: 32–35.
• Bi, S., Zheng, X., Meng, J., Wang, X., Robinson, N. & Davis, B. 2016. A new symmetrodont mammal (Trechnotheria: Zhangheotheriidae) from the Early Cretaceous of China and trechnotherian character evolution. Scientific Reports 6: 26668. DOI: 10.1038/srep26668

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