''Docodon'' (meaning 'beam tooth') is an extinct
docodont
Docodonta is an Order (biology), order of extinct Mesozoic Mammaliaformes, mammaliaforms (advanced cynodonts closely related to true Crown group, crown-group mammals). They were among the most common mammaliaforms of their time, persisting from t ...
mammaliaform
Mammaliaformes ("mammalian forms") is a clade of synapsid tetrapods that includes the crown group mammals and their closest extinct relatives; the group radiated from earlier probainognathian cynodonts during the Late Triassic. It is defined a ...
from the
Late Jurassic
The Late Jurassic is the third Epoch (geology), epoch of the Jurassic Period, and it spans the geologic time scale, geologic time from 161.5 ± 1.0 to 143.1 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic stratum, strata.Owen ...
of western North America. It was the first docodont to be named.
Description

''Docodon'' was the first docodontan cynodont found and named, and later gave its name to the family
Docodontidae as well as the order
Docodonta
Docodonta is an Order (biology), order of extinct Mesozoic Mammaliaformes, mammaliaforms (advanced cynodonts closely related to true Crown group, crown-group mammals). They were among the most common mammaliaforms of their time, persisting from t ...
.
[Kretzoi, M. (1946). "On Docodonta, a new order of Jurassic Mammals". ''Anneles Historico-Naturales Musei Nationalis Hungarici''. 39 :108-111.] Docodonts had more complex shaped teeth than other early non-mammalian mammaliaforms, with piercing and crushing surfaces that would have allowed members of this family to eat a wider range of food types. These complex teeth are more similar to those of later mammal groups, but evolved independently of them.
Unlike many of its coexisting mammal relatives from the Mesozoic, ''Docodon'' is known from a large number of teeth and jaws of differing growth stages. This has made it possible to study the growth of this docodontan, and has revealed how docodont jaws change from juvenile stages to adulthood.
Discovery
''Docodon'' was discovered by
William Harlow Reed and named by
Othniel Charles Marsh
Othniel Charles Marsh (October 29, 1831 – March 18, 1899) was an American professor of paleontology. A prolific fossil collector, Marsh was one of the preeminent paleontologists of the nineteenth century. Among his legacies are the discovery or ...
in 1880.
Like many other early small mammaliaforms, it is known mainly from fossilized teeth and jaws, as these are the hardest parts of the body and survive more easily in the fossil record. ''Docodon'' fossils are found most commonly in the
Black Hills region of South Dakota.
Its height is estimated at 10 centimeters with an approximate weight of 30 grams, making it one of the larger mammaliaforms known from the
Morrison Formation
The Morrison Formation is a distinctive sequence of Upper Jurassic sedimentary rock found in the western United States which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltston ...
.
Species
A number of species have been erected, but most are now considered to represent ''D. victor'', with differences being attributed to differing ages of the individuals represented.
[Chure, D. J.; Litwin, R.; Hasiotis, S. T.; Evanoff, E. & Carpenter, K. (2006). "The fauna and flora of the Morrison Formation". In ''Palaeontology and Geology of the Upper Jurassic Morrison Formation''. Foster, J. R & Lucas, S. G. R. M. (eds). ''New Mexico Museum of Natural History and Science Bulletin'' 36.] However, ''D. apoxys'' is still considered a separate species from ''D. victor'' due to differing numbers of tooth roots.
[Schultz, J. A.; Bhullar, B.-A. S. & Luo, Z.-X. (2018)]
"Re-examination of the Jurassic mammaliaform ''Docodon victor'' by computed tomography and occlusal functional analysis"
''Journal of Mammalian Evolution''. in press.
*''Docodon victor''
*''Docodon apoxys''
*''Docodon hercynicus''
See also
*
Morrison Formation
The Morrison Formation is a distinctive sequence of Upper Jurassic sedimentary rock found in the western United States which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltston ...
**
Mammaliaforms of the Morrison Formation
References
External links
DocodonDocodon LibraryMammal Genus
{{Taxonbar, from=Q3232173
Docodonta
Jurassic vertebrates of North America
Morrison fauna
Taxa named by Othniel Charles Marsh
Fossil taxa described in 1881