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Temporal range: Jurassic
Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Clade: Therapsida
Clade: Cynodontia
Genus: Microdocodon
Zhou et al., 2019
M. gracilis
Binomial name
Microdocodon gracilis
Zhou et al., 2019

Microdocodon is a genus of docodontian primitive mammaliaform ancestor from the Jurassic. It contains a single species, Microdocodon gracilis.


The species is notable for providing insight into the evolution of the ability to chew and suckle in early relatives of mammals, by preserving a nearly intact hyoid that is important in mammals to such motions. The complexity of the structure suggests that chewing and suckle evolved before mammals proper did, in the mammaliaforms, but after the split with cynodonts. This means the primary feature that marks crown mammals apart from nonmammals like mammaliaforms is the evolution of the middle ear disconnecting from the mandible in crown mammals.[1]

The species is thought to have been a small, shrew-like tree dwelling insectivore, weighing about 9 grams. Microdocodon lived at the same time as semiaquatic Castorocauda, the subterranean mammaliaform Docofossor, and Agilodocodon which was also arboreal.

See also[edit]


  1. ^ Zhou, Chang-Fu; Bhullar, Bhart-Anjan; Neander, April; Martin, Thomas; Luo, Zhe-Xi (19 Jul 2019). "New Jurassic mammaliaform sheds light on early evolution of mammal-like hyoid bones". Science. 365 (6450): 276–279. Bibcode:2019Sci...365..276Z. doi:10.1126/science.aau9345. PMID 31320539.