Desmostylus

{{Short description|Extinct family of mammals}} {{Automatic taxobox | fossil_range = {{Fossil range|Oligocene|Miocene}} | image = Desmostylus ROM.jpg | image_caption = ''Desmostylus'', Royal Ontario Museum | image2 = Desmostylus_3_NT.jpg | image2_caption = Restoration of ''D. hesperus'' | taxon = Desmostylus | authority = {{Harvnb|Marsh|1888}} | subdivision_ranks = Species | subdivision = *†''D. hesperus'' (type) {{Harvnb|Marsh|1888}} *†''D. coalingensis'' {{Harvnb|Reinhart|1959}} *†''D. japonicus'' {{Harvnb|Tokunaga|Iwasaki|1914}} | synonyms = *†''Vanderhoofius coalingensis'' }}

'''''Desmostylus'''''<ref>"bound pillar", from Greek {{lang|grc| δεσμός}} (''desmos''), bond, and {{lang|grc|στῦλος}} (''stulos''), pillar, referring to the shape of the molars.</ref> 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 {{Mya|28.4-7.2|million years}}.<ref name="Paleodb36958">{{Paleodb|36958|Desmostylus}}. Retrieved March 2013.</ref>

==Description== [[File:Desmostylus Skull.jpg|thumb|left|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 {{cvt|275|cm|ft}} in length, {{cvt|105|cm|ft}} in height and {{convert|1283|kg|lb}} 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 {{convert|2.8|MT|ST}}.<ref>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</ref> 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.<ref name=EoDP>{{Harvnb|Palmer|1999| p=228}}</ref>

Most likely fully aquatic, ''Desmostylus'' is thought to have lived in shallow water in coastal regions, usually less than 30 meters deep.<ref>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.</ref> 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.<ref>{{Harvnb|Clementz|Hoppe|Koch|2003}}</ref>

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.<ref name="Hayashi2013">{{cite journal|last1= Hayashi|first1= S.|last2= Houssaye|first2= A.|last3= Nakajima|first3= Y.|last4= Chiba|first4= K.|last5= Ando|first5= T.|last6= Sawamura|first6= H.|last7= Inuzuka|first7= N.|last8= Kaneko|first8= N.|last9= Osaki|first9= T.|title= Bone Inner Structure Suggests Increasing Aquatic Adaptations in Desmostylia (Mammalia, Afrotheria)|journal= PLOS ONE|volume= 8|issue= 4|year= 2013|article-number= e59146|doi= 10.1371/journal.pone.0059146|oclc= 837402105 |pmid= 23565143|pmc= 3615000|bibcode= 2013PLoSO...859146H|doi-access= free}}</ref>

==Species== ''Desmostylus hesperus'' (synonyms and invalid names: ''D. watasei'', ''D. cymatias'', ''D. californicus'', ''D. mirabilis'', ''D. minor'', ''Desmostylella typica''),<ref name="Paleodb36958" /> ''D. coalingensis'' (syn. ''Vanderhoofius coalingensis''),<ref name=Tomida>{{Harvnb|Tomida|Ohta|2007|p=60}}</ref><ref name=Inuzuka>{{Harvnb|Inuzuka|Domning|Ray|1984}}</ref> and ''D. japonicus''.

{{Harvnb|Marsh|1888}} named the type specimen ''D. hesperus'' based on a set of isolated teeth that had been found near Mission San Jose, California (type locality: {{Coord|37.6|-121.9|display=inline}}, paleocoordinates {{Coord|36.8|-117.6|display=inline}}).<ref>{{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}}</ref> Marsh described his specimen as a sirenian and proposed affinities with ''Metaxytherium'' (a genus of extinct dugongs) and ''Halicore'' (an obsolete name for dugong).<ref>{{Harvnb|Marsh|1888|p=96}}</ref>

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.<ref name="Uno-Kimura">{{Harvnb|Uno|Kimura|2004|p=1}}</ref>

''Desmostylus japonicus'' was described by {{Harvnb|Yoshiwara|Iwasaki|1902}} based on a well-preserved partial skull and named by {{Harvnb|Tokunaga|Iwasaki|1914}}. It has been reproposed as distinct species based on cranial morphology.<ref name="Uno-Kimura" />

==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.<ref name="Paleodb36958" />

==Notes== {{Commons category}} {{Portal|Paleontology}} {{Reflist}}

==References== {{Refbegin}} * {{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)029<0506:APPTHA>2.0.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 web |title=O. C. Marsh 1888 |website=Fossilworks |url=https://paleobiodb.org/classic/displayRefResults?reference_no=4363}} * {{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 }} {{Refend}}

Category:Desmostylians Category:Miocene mammals Category:Tortonian genus extinctions Category:Miocene mammals of Asia Category:Miocene mammals of North America Category:Prehistoric placental genera Category:Fossil taxa described in 1888 Category:Taxa named by Othniel Charles Marsh Category:Chattian genus first appearances Category:Fossils of Japan Category:Fossils of the United States Category:Fossils of Mexico Category:Fossils of Russia