Docodon

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Docodon
Temporal range: Upper Jurassic
Docodon bronze Deep Time.jpg
Bronze model of upper and lower jaws
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Synapsida
Clade: Therapsida
Clade: Cynodontia
Clade: Mammaliaformes
Order: Docodonta
Family: Docodontidae
Genus: Docodon
Marsh, 1881 [1]
Species
  • D. victor(Marsh, 1880) [1]
  • D. affinis(Marsh, 1880)*
  • D. crassus(Marsh, 1880)*
  • D. striatusMarsh, 1881, type*
  • D. superus(Simpson 1929)*
  • D. apoxys(Rougler, Sheth, Carpenter, Appella-Guiscafre & Davis, 2014) [2]
  • D. hercynicusMartin et al., 2024 [3]

*probable synonyms

Docodon (meaning 'beam tooth') is an extinct docodont mammaliaform from the Late Jurassic of western North America. It was the first docodont to be named.

Description

Docodon striatus American Jurassic Mammals plate IX Docodon striatus.jpg
Docodon striatus

Docodon was the first docodontan cynodont found and named, and later gave its name to the family Docodontidae as well as the order Docodonta. [4] 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. [5]

Discovery

Docodon was discovered by William Harlow Reed and named by Othniel Charles Marsh in 1880. [1] 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. [6]

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. [7] However, D. apoxys is still considered a separate species from D. victor due to differing numbers of tooth roots. [5]

See also

Related Research Articles

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Castorocauda is an extinct, semi-aquatic, superficially otter-like genus of docodont mammaliaforms with one species, C. lutrasimilis. It is part of the Yanliao Biota, found in the Daohugou Beds of Inner Mongolia, China dating to the Middle to Late Jurassic. It was part of an explosive Middle Jurassic radiation of Mammaliaformes moving into diverse habitats and niches. Its discovery in 2006, along with the discovery of other unusual mammaliaforms, disproves the previous hypothesis of Mammaliaformes remaining evolutionarily stagnant until the extinction of the non-avian dinosaurs.

<span class="mw-page-title-main">Docodonta</span> Extinct order of mammaliaforms

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<span class="mw-page-title-main">Mammaliaformes</span> Clade of mammals and extinct relatives

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<span class="mw-page-title-main">Haramiyida</span> Extinct order of mammaliaforms

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<span class="mw-page-title-main">Paleobiota of the Morrison Formation</span>

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<i>Haldanodon</i> Extinct genus of mammaliaforms

Haldanodon is an extinct docodont mammaliaform which lived in the Upper Jurassic. Its fossil remains have been found in Portugal, in the well-known fossil locality of Guimarota, which is in the Alcobaça Formation. It may have been a semi-aquatic burrowing insectivore, similar in habits to desmans and the platypus. Several specimens are known, include a partial skeleton and well-preserved skulls.

<i>Docofossor</i> Extinct genus of mammaliaforms

Docofossor is an extinct mammaliaform from the Jurassic period. Its remains have been recovered in China from 160 million years old rocks. It appears to have been the earliest-known subterranean mammaliaform, with adaptations remarkably similar to the modern Chrysochloridae, the golden moles.

<i>Borealestes</i> Extinct genus of mammaliaforms

Borealestes is a genus of docodontan from the Middle Jurassic of Britain, first discovered on the Isle of Skye near the village of Elgol. It was the earliest mammaliaform from the Mesozoic found and named in Scotland. A second species and was later found in other Middle Jurassic sites in England, but is now shown to be a different genus. A new species, B. cuillinensis was named in 2021, also from Skye.

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Tikitherium is an extinct genus of mammaliaforms from India, known from a single upper tooth. Originally argued to be a primitive mammaliaform from the Late Triassic, a 2024 study argued that it actually represented the remains of a shrew from the Neogene. Tikitherium refers to Tiki, the village located near the Tiki Formation where the specimen was originally thought to have come from, and therium is Greek for “Beast”. The species was named copei in honor of Edward Drinker Cope for his pioneering discoveries towards understanding mammalian molars.

Peraiocynodon is an extinct mammaliaform from the order Docodonta, found in the Middle Jurassic rocks of the United Kingdom. It is only known from isolated molar teeth found in the mammal bed at Kirtlington cement quarry in Oxfordshire, England.

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Krusatodon is a genus of extinct docodont mammaliaform from the Middle Jurassic of the United Kingdom. It is known from the Forest Marble Formation, Kirtlington, in England, and also from a single molar tooth in the Kilmaluag Formation on the Isle of Skye, Scotland.

Gondtherium is a genus of extinct mammaliaform from the Kota Formation in India. It was considered a docodontan by those who described it, but it remains unclear if this is the case.

Simpsonodon is an extinct genus of docodontan mammaliaform known from the Middle Jurassic of England, Kyrgyzstan and Russia. The type species S. oxfordensis was described from the Kirtlington Mammal Bed and Watton Cliff in the Forest Marble Formation of England. It was named after George Gaylord Simpson, a pioneering mammalologist and contributor to the Modern Evolutionary Synthesis. A second species S. sibiricus is known from the Itat Formation of Russia, and indeterminate species of the genus are also known from the Balabansai Formation in Kyrgyzstan

Itatodon is an extinct genus of primitive mammaliaforms known from the Bathonian aged Itat Formation of Russia. The genus is named after the formation, with the species being named after Leonid Petrovich Tatarinov who described the first docodont from Asia. It is known from a holotype right lower molar and referred isolated right lower molar and fragment of the left lower molar. When it was first described, it was thought to be a docodontan, but one recent phylogenetic studies have assigned it, along with its close relative Paritatodon to Shuotheriidae, while others continue to consider it a docodont.

Dobunnodon its an extinct genus of docodont from the Middle Jurassic (Bathonian) Forest Marble Formation of England, first discovered in Oxfordshire near the village of Kirtlington. The type species, D. mussettae, was originally named as a species of Borealestes in 2003.

Sibirotherium is an extinct genus of docodont mammaliaform. It is known from only a single named species, Sibirotherium rossicum, known from jaw fragments and teeth found in the Early Cretaceous (Aptian) aged Ilek Formation in western Siberia, alongside Khorotherium also from Siberia, it is one of the youngest docodonts.

References

  1. 1 2 3 4 Marsh, O. C. (1880). "Notice on Jurassic mammals representing two new orders". American Journal of Science. 20 :235-239.
  2. 1 2 Rougier, G. W.; Sheth, A. S.; Carpenter, K.; Appella-Guiscafre, L. & Davis, B. M. (2014). "A new species of Docodon (Mammaliaformes: Docodonta) from the Upper Jurassic Morrison Formation and a reassessment of selected craniodental characters in basal mammaliaforms". Journal of Mammalian Evolution. 22: 1-16.
  3. 1 2 Martin, T.; Averianov, A. O.; Lang, A. J.; Schultz, J. A.; Wings, O. (2024). "Docodontans (Mammaliaformes) from the Late Jurassic of Germany". Historical Biology: 1–9. doi:10.1080/08912963.2023.2300635. S2CID   267167016.
  4. Kretzoi, M. (1946). "On Docodonta, a new order of Jurassic Mammals". Anneles Historico-Naturales Musei Nationalis Hungarici. 39 :108-111.
  5. 1 2 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. doi : 10.1007/s10914-017-9418-5
  6. Foster, J. R.; Trujillo, K. C.; Madsen, S. K. & Martin, J. E. (2006). "The Late Jurassic mammal Docodon, from the Morrison Formation of the Black Hills, Wyoming: implications for abundance and biogeography of the genus". New Mexico Museum of Natural History and Science Bulletin. 36: 165–169.
  7. 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 Bulletin36.