Yinotheria

Yinotheria
Temporal range: Middle Jurassic–Holocene (possible Late Triassic record[1])
Ambondro mahabo jaw fragment
Shuotherium dongi jawbone
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Subclass: Yinotheria
Chow and Rich, 1982[2]
Subgroups

Yinotheria is a proposed basal subclass clade of crown mammals uniting the Shuotheriidae, an extinct group of mammals from the Jurassic of Eurasia, with Australosphenida, a group of mammals known from the Jurassic to Cretaceous of Gondwana, which possibly include living monotremes.[3] Today, there are only five surviving species of monotremes which live in Australia and New Guinea, consisting of the platypus and four species of echidna. Fossils of yinotheres have been found in Britain, China, Russia, Madagascar and Argentina. Contrary to other known crown mammals, they retained postdentary bones as shown by the presence of a postdentary trough. The extant members (monotremes) developed the mammalian middle ear independently.

Other studies have rejected Yinotheria, finding Shuotheriidae to be unrelated to Australosphenida and outside crown Mammalia.[4]

  1. ^ Hugall, A.F.; et al. (2007). "Calibration choice, rate smoothing, and the pattern of tetrapod diversification according to the long nuclear gene RAG-1". Syst. Biol. 56 (4): 543–63. doi:10.1080/10635150701477825. hdl:2440/44140. PMID 17654361.
  2. ^ 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.
  3. ^ Luo, Zhe-Xi; Ji, Qiang; Yuan, Chong-Xi (2007). "Convergent dental adaptations in pseudo-tribosphenic and tribosphenic mammals". Nature. 450 (7166): 93–97. Bibcode:2007Natur.450...93L. doi:10.1038/nature06221. PMID 17972884. S2CID 609206. Retrieved 26 December 2014.
  4. ^ 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.