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Nuvola apps important.svg This taxon is (or may be) paraphyletic


Superregnum: Eukaryota
Cladus: Unikonta
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Megaclassis: Osteichthyes
Cladus: Sarcopterygii
Cladus: Rhipidistia
Cladus: Tetrapodomorpha
Cladus: Eotetrapodiformes
Cladus: Elpistostegalia
Superclassis: Tetrapoda
Cladus: Reptiliomorpha
Cladus: Amniota
Cladus: Synapsida
Cladus: Eupelycosauria
Cladus: Sphenacodontia
Cladus: Sphenacodontoidea
Cladus: Therapsida
Cladus: Theriodontia
Subordo: Cynodontia
Infraordo: Eucynodontia
Cladus: Probainognathia
Cladus: Prozostrodontia
Cladus: Mammaliaformes
Classis: Mammalia
Subclassis: “Symmetrodonta
Familiae overview (historical usage): Amphidontidae – Bondesiidae – Kuehneotheriidae – Shuotheriidae – Spalacotheriidae – Tinodontidae – Thereuodontidae – Woutersiidae – Zhangheotheriidae
Familiae overview (stricto sensu): Spalacotheriidae – Zhangheotheriidae


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.


Primary references[edit]

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

Additional references[edit]

  • 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

Vernacular names[edit]

català: Simetrodonts
English: Symmetrodonts
français: Symmetrodonts
русский: Симметродонты