# Kayentatherium > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Kayentatherium > Markdown URL: https://mediated.wiki/source/Kayentatherium.md > Source: https://en.wikipedia.org/wiki/Kayentatherium > Source revision: 1343744377 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) {{Short description|Extinct genus of mammaliamorphs}} {{Automatic taxobox | fossil_range = {{Fossil range|Early Jurassic}} | image = Kayentatherium wellesi.jpg | image_caption = Skull of ''K. wellesi'' | taxon = Kayentatherium | authority = Kermack, 1982 | type_species = {{extinct}}'''''Kayentatherium wellesi''''' | type_species_authority = Kermack, 1982 | synonyms = * '''''Nearctylodon broomi''''' Lewis, 1986 }} '''''Kayentatherium''''' is an extinct [genus](/source/genus) of [tritylodontid](/source/tritylodontid) [cynodont](/source/cynodont)s that lived during the [Early Jurassic](/source/Early_Jurassic). It is one of two tritylodonts from the [Kayenta Formation](/source/Kayenta_Formation) of northern [Arizona](/source/Arizona), United States. ''Kayentatherium'' means "Kayenta Beast", and is named for the geological formation in which it was found, the [Kayenta Formation](/source/Kayenta_Formation). ''Kayentatherium'' is known from several specimens.Kermack, D. 1982. A new tritylodont from the Kayenta Formation of Arizona. Zoological Journal of the Linnean Society, 76. 1-17.Sues, Hans-Dieter & F. A. Jenkins. 2006. The Postcranial Skeleton of Kayentatherium Wellesi from the Lower Jurassic Kayenta Formation of Arizona and the Phylogenetic Significance of Postcranial Features in Tritylodontid Cynodonts in: Carrano, Matthew T., Gaudin, T. J., Blob, R. W. and Wible, J. R., Amniote Paleobiology: Perspectives on the Evolution of Mammals, Birds, and Reptiles: The University of Chicago Press. pp. 114-152. The specific name honors paleontologist [Samuel Welles](/source/Samuel_Paul_Welles), who worked with the [University of California Museum of Paleontology](/source/University_of_California_Museum_of_Paleontology) in much of the pioneering work on the paleontology of the Kayenta Formation. ==History== The first tritylodontid material found within the Kayenta Formation was collected by members of the [United States Geological Survey](/source/United_States_Geological_Survey) in 1953. Further material was collected in 1977 and 1982 by a team led by [Farish Jenkins](/source/Farish_Jenkins). Also found in the same rocks were ''[Dinnebitodon amarali](/source/Dinnebitodon_amarali)'' and ''Nearctylodon broomi'', but the latter was later considered to be a juvenile specimen of ''Kayentatherium'', and so was synonymised. ==Description== thumb|left|Artist's restoration of ''K. wellesi'' It was about a meter long, the skull was over {{convert|20|cm|inch}} in length. It was a robust and stocky animal with a large head and stout backbone. Some researchers think it might have been semi-aquatic, with adaptations formerly thought to indicate digging habits now interpreted as specialisation towards limb-powered swimming.Anusuya Chinsamy-Turan, Forerunners of Mammals: Radiation • Histology • Biology, Indiana University Press, 18/11/2011 Slight flattening and flaring of the tail vertebrae also suggest specialisms for a semi-aquatic ecology.Hoffman E, and Rowe TB. 2017 Postcranial anatomy of ''Kayentatherium wellesi'': swimming adaptations in a mammaliamorph from the Early Jurassic. Abstract from the Society of Vertebrate Paleontology Annual Conference. If this was the case, it would be one of the earliest examples of semi-aquatic specialism in mammaliamorphs in the mammal fossil record. ==Reproduction== {{multiple image | align = right | direction = horiztontal | width = 150 | perrow=2/2 | footer = Skulls of ''Kayentatherium'' sp. in the [American Museum of Natural History](/source/American_Museum_of_Natural_History) showing a growth series from young to adult. | image1 = Kayentatherium sp AMNH 7659.jpg | image2 = Kayentatherium sp AMNH 7650.jpg | image3 = Kayentatherium sp AMNH 7652.jpg | image4 = Kayentatherium sp AMNH 7651.jpg }} A find in 2000 of ''Kayentatherium wellesi'' from the Kayenta formation of Arizona was examined by [microCT](/source/microCT) scan, and revealed an adult with at least 38 [perinate](/source/perinate)s, a number considerably higher than any living mammal litter. The size of the group suggests a clutch of eggs. Perinates had similar skull proportions to adults, with well-developed teeth, and may have been able to fend for themselves at birth.{{Cite journal|last=Pickrell|first=John|date=2019-10-23|title=How the earliest mammals thrived alongside dinosaurs|journal=Nature|language=en|volume=574|issue=7779|pages=468–472|doi=10.1038/d41586-019-03170-7|pmid=31645742|bibcode=2019Natur.574..468P |doi-access=free}} Allometric study shows that tritylodontids had proportionally smaller brains at this stage than mammal perinates, which supports the hypothesis that the evolution of larger brain size in early mammals was associated with changes in reproductive strategy to invest more parental energy in a smaller number of offspring.{{cite journal | last1 = Hoffman | first1 = Eva A. | last2 = Rowe | first2 = Timothy B. | year = 2018 | title = Jurassic stem-mammal perinates and the origin of mammalian reproduction and growth | url = | journal = Nature | volume = 561 | issue = 7721| pages = 104–108 | doi = 10.1038/s41586-018-0441-3 | pmid = 30158701 }} ==See also== {{Portal|Paleontology}} * ''[Dinnebitodon](/source/Dinnebitodon)'' * ''[Oligokyphus](/source/Oligokyphus)'' * [Tritylodontidae](/source/Tritylodontidae) ==References== {{Reflist}} {{Cynodontia|P.}} {{Taxonbar|from=Q6380561}} Category:Tritylodontidae Category:Early Jurassic synapsids of North America Category:Kayenta Formation Category:Fossil taxa described in 1982 --- Adapted from the Wikipedia article [Kayentatherium](https://en.wikipedia.org/wiki/Kayentatherium) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Kayentatherium?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.