Desmostylus

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Extinct family of mammals

title: "Desmostylus" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["desmostylians", "miocene-mammals", "tortonian-genus-extinctions", "miocene-mammals-of-asia", "miocene-mammals-of-north-america", "prehistoric-placental-genera", "fossil-taxa-described-in-1888", "taxa-named-by-othniel-charles-marsh", "chattian-genus-first-appearances", "fossils-of-japan", "fossils-of-the-united-states", "fossils-of-mexico", "fossils-of-russia"] description: "Extinct family of mammals" topic_path: "geography/japan" source: "https://en.wikipedia.org/wiki/Desmostylus" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Extinct family of mammals ::

| fossil_range = | image = Desmostylus ROM.jpg | image_caption = Desmostylus, Royal Ontario Museum | image2 = Desmostylus_3_NT.jpg | image2_caption = Restoration of D. hesperus | taxon = Desmostylus | authority = | subdivision_ranks = Species | subdivision =

  • †D. hesperus (type)

  • †D. coalingensis

  • †D. japonicus

| synonyms =

  • †Vanderhoofius coalingensis

Desmostylus is an extinct genus of herbivorous mammal of the family Desmostylidae living from the Chattian stage of the Late Oligocene subepoch through the Late Miocene subepoch (28.4 mya–7.250 Mya) and in existence for approximately .

Description

::figure[src="https://upload.wikimedia.org/wikipedia/commons/b/b4/Desmostylus_Skull.jpg" caption="Skull of ''D. japonicus'' at the [[National Museum of Nature and Science]], [[Tokyo]], [[Japan]]. [[Holotype"] ::

Desmostylus was a large, hippopotamus-like creature, with the adult Keton specimen of D. hesperus measuring 275 cm in length, 105 cm in height and 1283 kg in body mass; the largest known humerus, which is 1.3 times that of the Keton specimen in length, probably belonged to an individual with a mass of 2.8 MT. It had a short tail and powerful legs with four hooves. The animal's jaws were elongated and sported forward-facing tusks, which were elongated canines and incisors.

Most likely fully aquatic, Desmostylus is thought to have lived in shallow water in coastal regions, usually less than 30 meters deep. Recent isotope work indicates that Desmostylus more likely lived (or spent a large amount of time) in freshwater or estuary ecosystems foraging for aquatic freshwater plants.

Its less dense bone structure suggests that Desmostylus had a lifestyle of active swimming and possibly feeding at the surface, unlike other desmostylians that were primarily slow swimmers and/or bottom walkers and sea grass feeders.

Species

Desmostylus hesperus (synonyms and invalid names: D. watasei, D. cymatias, D. californicus, D. mirabilis, D. minor, Desmostylella typica), D. coalingensis (syn. Vanderhoofius coalingensis), and D. japonicus.

named the type specimen D. hesperus based on a set of isolated teeth that he had found near Mission San Jose, California (type locality: , paleocoordinates ).{{Cite web | title = Mission San Jose, east (Miocene of the United States) | publisher = Fossilworks | url = https://paleobiodb.org/classic/displayCollResults?collection_no=13093 | access-date = 17 December 2021}} Marsh described his specimen as a sirenian and proposed affinities with Metaxytherium (a genus of extinct dugongs) and Halicore (an obsolete name for dugong).

Several other species were later described based on minor differences in tooth morphology. Most or all of these species have been synonymized with D. hesperus since variation in tooth morphology between individuals assigned to one of these species has proven to be to greater than the differences between species.

Desmostylus japonicus was described by based on a well-preserved partial skull and named by . It has been reproposed as distinct species based on cranial morphology.

Fossil distribution

Fossils have been discovered from along the northern Pacific Rim from Baja California Peninsula northward along the coast of California, Oregon, Washington and west to Sakhalin Island, Hokkaido, and south to the Shimane Prefecture.

Notes

References

  • {{Cite journal | last1 = Clementz | first1 = Mark T. | last2 = Hoppe | first2 = Kathryn A. | last3 = Koch | first3 = Paul L. | title = A paleoecological paradox: the habitat and dietary preferences of the extinct tethythere Desmostylus, inferred from stable isotope analysis | year = 2003 | journal = Paleobiology | volume = 29 | issue = 4 | pages = 506–519 | url = http://paleobiol.geoscienceworld.org/cgi/content/abstract/29/4/506 | doi = 10.1666/0094-8373(2003)0292.0.CO;2 | bibcode = 2003Pbio...29..506C | s2cid = 12567121 | oclc = 211272891| url-access = subscription}}
  • {{Cite journal | last1 = Inuzuka | first1 = Norihisa | last2 = Domning | first2 = Daryl P. | last3 = Ray | first3 = Clayton E. | title = Summary of taxa and morphological adaptations of the Desmostylia | year = 1984 | journal = Island Arc | volume = 3 | issue = 4 | pages = 522–537 | doi = 10.1111/j.1440-1738.1994.tb00131.x}}

  • {{Cite journal | last = Marsh | first = O. C. | author-link = Othniel Charles Marsh | title = Notice of a new fossil sirenian, from California | year = 1888 | journal = American Journal of Science | volume = 25 | issue = 8 | pages = 94–96 | doi = 10.2475/ajs.s3-35.205.94 | bibcode = 1888AmJS...35...94M | s2cid = 129254943 | url = https://www.biodiversitylibrary.org/item/124438#page/106/mode/2up | access-date = 17 December 2021 | oclc = 79838746}}

  • {{Cite book | last = Palmer | first = Douglas | title = The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals | year = 1999 | publisher = Marshall Editions | location = London | isbn = 1-84028-152-9 | oclc = 313633743}}
  • {{Cite journal | last = Reinhart | first = Roy Herbert | author-link = Roy Herbert Reinhart | title = A review of the Sirenia and Desmostylia | year = 1959 | journal = University of California Publications in Geological Sciences | volume = 36 | issue = 1 | pages = 1–146 | oclc = 3474601}}
  • {{Cite journal | last1 = Tokunaga | first1 = Shigeyasu |author1-link=Shigeyasu Tokunaga | last2 =Iwasaki | first2 = C. | title = Notes on Desmostylus japonicus |journal=The Journal of the Geological Society of Japan |volume=21 |issue=255 |page=33 |doi=10.5575/geosoc.21.255_33 |doi-access=free | year = 1914
  • {{Cite journal | last1 = Tomida | first1 = Yukimitsu | last2 = Ohta | first2 = Toshikazu | title = Discovery of a desmostylian tooth from Kitami City, northeastern Hokkaido, Japan | year = 2007 | journal = Memoir of the Fukui Prefectural Dinosaur Museum | volume = 6 | pages = 57–61 | url = http://www.dinosaur.pref.fukui.jp/archive/memoir/memoir006-057.pdf | access-date = 1 December 2013
  • {{Cite journal | last1 = Uno | first1 = Hikaru | last2 = Kimura | first2 = Masaichi | title = Reinterpretation of some cranial structures of Desmostylia hesperus (Mammalia, Desmostylia): A new specimen from the Middle Miocene Tachikaraushinai Formation, Hokkaido, Japan | year = 2004 | journal = Paleontological Research | volume = 8 | issue = 1 | pages = 1–10 | url = http://ci.nii.ac.jp/els/110002664617.pdf?id=ART0002933234&type=pdf | access-date = 1 December 2013 | doi=10.2517/prpsj.8.1| doi-access = free }}
  • {{Cite journal | last1 = Yoshiwara | first1 = Shigeyasu |author1-link=Shigeyasu Tokunaga | last2 = Iwasaki | first2 = Jūzō | title = Notes on a New Fossil Mammal | year = 1902 | journal = Journal of the College of Science, Imperial University, Tokyo, Japan | volume = 16 | url = https://www.biodiversitylibrary.org/item/31353#page/333/mode/1up | format = PDF | access-date = 13 June 2023

References

  1. "bound pillar", from [[Greek language. Greek]] {{lang. grc. δεσμός (''desmos''), bond, and {{lang. grc. στῦλος (''stulos''), pillar, referring to the shape of the molars.
  2. {{Paleodb. 36958. Desmostylus. Retrieved March 2013.
  3. Inuzuka, N. (1996). Body size and mass estimates of desmostylians(Mammalia). The Journal of the Geological Society of Japan, 102(9), 816–819. https://doi.org/10.5575/geosoc.102.816
  4. {{Harvnb. Palmer. 1999
  5. Kumiko Matsui; Katsuo Sashida; Sachiko Agematsu; Naoki Kohno (2017). "Habitat preferences of the enigmatic Miocene tethythere Desmostylus and Paleoparadoxia (Desmostylia; Mammalia) inferred from the depositional depth of fossil occurrences in the Northwestern Pacific realm". Palaeogeography, Palaeoclimatology, Palaeoecology. 471: 254–265. doi:10.1016/j.palaeo.2017.02.005.
  6. {{Harvnb. Clementz. Hoppe. Koch. 2003
  7. (2013). "Bone Inner Structure Suggests Increasing Aquatic Adaptations in Desmostylia (Mammalia, Afrotheria)". PLOS ONE.
  8. {{Harvnb. Tomida. Ohta. 2007
  9. {{Harvnb. Inuzuka. Domning. Ray. 1984
  10. {{Harvnb. Marsh. 1888
  11. {{Harvnb. Uno. Kimura. 2004

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desmostyliansmiocene-mammalstortonian-genus-extinctionsmiocene-mammals-of-asiamiocene-mammals-of-north-americaprehistoric-placental-generafossil-taxa-described-in-1888taxa-named-by-othniel-charles-marshchattian-genus-first-appearancesfossils-of-japanfossils-of-the-united-statesfossils-of-mexicofossils-of-russia