Urtinotherium

{{Short description|Extinct genus of mammals}} {{Distinguish|Uintatherium}} {{Italic title}}{{Automatic taxobox | name = ''Urtinotherium'' | taxon = Urtinotherium | fossil_range = Eocene to Early Oligocene, {{fossil range|47|35}} | image = Urtinotherium.jpg | image_alt = | image_caption = Drawing of the holotype jaw IVPP V.2769. | authority = Chow & Chiu, 1963 | subdivision_ranks = Species | subdivision = * {{extinct}}'''''U. intermedium''''' * {{extinct}}'''''U. incisivum''''' Chow & Chiu, 1963 * {{extinct}}'''''U. yagouense''''' (Qui ''et al.'', 2004) * {{extinct}}'''''U. parvum''''' (Chow, 1958)<ref name="wangetal2013"/> | synonyms = * ''Turpanotherium''?<ref>{{Cite journal|last1=Lu |first1=X. |last2=Deng |first2=T. |title=Life history of a new paraceratheriid from the Early Oligocene of Northwest China |year=2025 |journal=Scientific Reports |volume=15 |issue=1 |article-number=28740 |doi=10.1038/s41598-025-13365-w |pmid=40770214 |pmc=12328695 |doi-access=free }}</ref> Qui & Wang, 2007 {{collapsible list|bullets=true|title=Species synonyms | {{extinct}}'''''Urtinotherium yagouense:''''' | {{extinct}}''Paraceratherium yagouense'' Qui ''et al.'', 2004 | {{extinct}}''Turpanotherium yagouense'' (Qui ''et al.'', 2004) | {{extinct}}''Turpanotherium elegans'' Qui & Wang, 2007 | {{extinct}}'''''Urtinotherium parvum:''''' | {{extinct}}''Indricotherium parvum'' Chow, 1958 | {{extinct}}''Indricotherium qujigensis'' Tang, 1978 }} }} '''''Urtinotherium''''' (meaning "Urtyn beast" in Ancient Greek) is an extinct genus of paracerathere mammals. It was a large animal that was closely related to ''Paraceratherium'', and found in rocks dating from the Late Eocene to Early Oligocene period. The remains were first discovered in the Urtyn Obo region (now Dorbod Banner, Ulanqab) in Inner Mongolia, which the name ''Urtinotherium'' is based upon. Other referred specimens are from northern China.<ref name="bayshashanov&lucas2001"/>

==Classification== ''Urtinotherium'' pertains to the Paraceratheriidae subfamily Paraceratheriinae. These in turn are part of the superfamily Rhinocerotoidea and therefore represent close relatives of modern rhinoceroses. The paraceratheres are distinguished by the formation of large sharp incisors in their upper and lower jaws, while rhinoceroses only have a two on the lower jaw. ''Urtinotherium'' was thought of by Leonard Radinsky to be a transitional form between earlier paraceratheres, like ''Juxia'', and later forms, such as ''Paraceratherium'' and ''Indricotherium'' (now ''Paraceratherium transouralicum'').<ref name="radinsky1966" />

This genus represents a primitive form of paracerathere that developed in the late Eocene. It is possibly descended from ''Juxia'', which lived during the Middle Eocene in northern China, and which shares with it having a full set of teeth in its jaws. However, ''Urtinotherium'' differs by its larger body size and greater specialization in the incisors.<ref name="chow&chiu1964" /> ''Urtinotherium'' and later ''Paraceratherium'' form the most derived section of the largest known rhinocerotoid lineage. In their specialization emphasizes that compared to ''Urtinotherium'', they possessed significantly reduced dentition with only a couple of incisors in the lower jaw.<ref name="lucas&sobus1989" />

The first description of ''Urtinotherium'' was published in 1963 by Zhou Ming-Zhen and Chiu Chan-Siang, based on the lower jaw. The type species is recognized as ''Urtinotherium incisivum''. The genus name comes from the location, and from the Ancient Greek word {{lang|grc|θηρίον}} ({{Transliteration|grc|therion}}) meaning "beast". The species name refers to its elongated incisivos.<ref name="chow&chiu1963" />

==Description== [[File:Urtinotherium NNHM.jpg|left|thumb|150x150px|Tooth, National Natural History Museum of China]] ''Urtinotherium'' was a representative of the large family Paraceratheriidae, and almost reached the proportions of ''Paraceratherium''. ''Urtinotherium'' evolved from Juxia and represents the beginning of paracerathere gigantism. ''U. parvum'' was the smallest species within the genus, weighing {{Convert|2.6|tonne|lb|}}. ''U. intermedium'' was the largest species within the genus {{Convert|4.9-6.1|tonne|lb|}}, based on limb bones and m1 regressions respectively. This made ''U. intermedium'' among the largest animals living in its environment, alongside the brontothere ''Embolotherium''.<ref>{{Cite journal | last1 = Deng | first1 = Tao | year = 2022 | title = Body mass of the giant rhinos (Paraceratheriinae, Mammalia) and its tendency in evolution | journal = Historical Biology | pages = 1–12 | doi = 10.1080/08912963.2022.2095908 | s2cid = 250366746 | url = https://www.tandfonline.com/doi/full/10.1080/08912963.2022.2095908 | url-access = subscription }}</ref> It is known from several findings in central and eastern Asia, though no complete skeletons are known. The holotype fossil (catalog number IVPP V.2769) includes a complete lower jaw {{convert|71.5|cm|in|abbr=on}} in length, comparable to the smallest known of ''Paraceratherium''. The jaw is wedge shaped, very low in height, and with elongated branches. The symphysis was solid and extended to the beginning of the second premolars. The jaw's dentition is complete, having three front incisors and canine. The first two incisors protrude forward with a crown length of {{convert|4.9|cm|in|abbr=on}}, with forms similar to daggers. The other incisors and canines had much smaller crowns. Between each tooth is a small space, similar to its phylogenetically primitive relatives such as ''Juxia''. Its back teeth, which are separated from the front teeth by a small diastema, consist of four premolars and three molars. These are similar in structure to those of ''Paraceratherium'', with small premolars and larger molars. The latter have low crowns (are brachyodont) and had few enamel folds.<ref name="chow&chiu1963"/>

==Paleoecology == The remains of ''Urtinotherium'' are found mainly in the eastern and central Asia, consisting mostly of jaw fragments and isolated teeth. The holotype jaw was found in the early 1960s in the Urtyn-Obo Formation of Inner Mongolia, which dates from the Late Eocene.<ref name="chow&chiu1963"/> Additional findings came from Yunnan province in China and Late Eocene deposits of Khoer-Dzan in Mongolia. Further findings have been made in Saissansee Aksyir Svita basin in eastern Kazakhstan, also of the same age.<ref name="bayshashanov&lucas2001"/> ''Urtinotherium'' likely survived into the Early Oligocene, as fossils probably from it have been found in the Mera Formation of Transylvania, Romania.<ref name="codrea2000"/>

The Ergilin Dzo Formation was initially to have been a relatively closed environment, with a warm and humid climate, based on the presence of brontotheres and the abundance of low crowned herbivores. Despite this, the absence of primates and rarity of crocodyliforms suggests there were more open areas and it was more arid than other contemporary formations.<ref name=":02">{{Cite journal |last1=Tsubamoto |first1=Takehisa |last2=Tsogtbaatar |first2=Khishigjav |last3=Chinzorig |first3=Tsogtbaatar |last4=Egi |first4=Naoko |date=2022 |title=A brief review of the updated fossil vertebrate fauna of the upper Eocene Ergilin Dzo Formation, southeastern Mongolia |url=http://earth.sci.ehime-u.ac.jp/~tsubamoto/TBM_Papers/Tsubamoto_etal_2022_Mem_Fac_Sci_Ehime_Univ_24.pdf |journal=Memoirs of the Faculty of Science, Ehime University |volume=24 |pages=64–83}}</ref> Sedimentary analysis within Khoer-Dzan found sediments of red soils, which are associated with floodplain environments, with no evidence of lacustrine environments.<ref name="Tsubamoto1">Tsubamoto, T., Saneyoshi, M., Watabe, M., Tsogbataar, K., Mainbayar, B. (2011). [https://bioone.org/journals/paleontological-research/volume-15/issue-4/1342-8144-15.4.258/The-Entelodontid-Artiodactyl-Fauna-from-the-Eocene-Ergilin-Dzo-Formation/10.2517/1342-8144-15.4.258.full The Entelodontid Artiodactyl Fauna from the Eocene Ergilin Dzo Formation of Mongolia with Comments on Brachyhyops and the Khoer Dzan Locality]. Paleontological Research, 15(4):258-268</ref>

''U. parvum'' coexisted with other herbivores such as the rhinocerotid ''Ronzotherium orientale'', the anthracothere ''Bothriodon'', the praetragulid ''Praetragulus electus'', the brontothere ''Embolotherium andrewsi'', and the chalicothere ''Schizotherium avitum''. Contemporary predators within the fauna include the hyaenodont ''Hyaenodon'', nimravids such as ''Eofelis'' and ''Nimravus intermedius'', and entelodonts ''Brachyhyops trofimovi'' and ''Entelodon gobiensis''.<ref>[https://paleobiodb.org/classic/basicCollectionSearch?collection_no=174716&is_real_user=1 PBDB: Khoer Dzan slope]</ref>

==References== <references> <ref name="bayshashanov&lucas2001">{{cite journal |last1=Bayshashanov |first1=U.B. |last2=Lucas |first2=S.G. |year=2001 |title=The giant rhinoceros ''Urtinotherium'' from the upper Eocene of the Zayan Basin, Kazakhstan |url=https://rhinoresourcecenter.com/wp-content/uploads/2011/02/1297032925.pdf |journal=Zoological Journal of Kazakhstan |pages=185–187 |issn=1024-7688 |authorlink2=Spencer G. Lucas}}</ref> <ref name="chow&chiu1963">{{cite journal|last1=Chow|first1=M.|last2=Chiu|first2=C.-S.|year=1963|title=New genus of giant rhinoceros from Oligocene of Inner Mongolia|url=http://www.ivpp.cas.cn/cbw/gjzdwxb/xbwzxz/201003/P020100323307682977746.pdf|journal=Vertebrata PalAsiatica|volume=7|issue=9|pages=230–239}}</ref> <ref name="codrea2000">{{cite book|last=Codrea|first=V.A.|year=2000|title=Rinoceri și Tapiri Terțiari din România|trans-title=Tertiary Rhinoceroses and Tapirs of Romania|publisher=Presa Universitara Clujeana|url=http://www.rhinoresourcecenter.com/index.php?s=1&act=pdfviewer&id=1359147399&folder=135|language=French|pages=145–147|isbn=973-8095-18-2}}</ref> <ref name="radinsky1966">{{cite journal|last=Radinsky|first=L.B.|year=1966|title=The families of the Rhinocerotoidea (Mammalia, Perissodactyla)|journal=Journal of Mammalogy|volume=47|issue=4|pages=631–639|jstor=1377893|doi=10.2307/1377893}}</ref> <ref name="chow&chiu1964">{{cite journal|last1=Chow|first1=M.|last2=Chiu|first2=C.-S.|year=1964|title=An eocene giant rhinoceros|journal=Vertebrata PalAsiatica|issue=8|pages=264–268}}</ref> <ref name="wangetal2013">{{cite journal|last1=Wang|first1=H.-B.|last2=Bai|first2=B.|last3=Gao|first3=F.|last4=Huang|first4=W.-C.|last5=Wang|first5=Y.-K.|year=2013|title=New eggysodontid (Mammalia, Perissodactyla) material from the Paleogene of the Guangnan Basin, Yunnan Province, China|url=http://lveho.ivpp.cas.cn/kycg/lw/201404/P020140409574695477775.pdf|journal=Vertebrata PalAsiatica|volume=51|issue=4|pages=307–322|archive-date=2023-02-06|access-date=2014-10-08|archive-url=https://web.archive.org/web/20230206044942/http://lveho.ivpp.cas.cn/kycg/lw/201404/P020140409574695477775.pdf|url-status=dead}}</ref> <ref name="lucas&sobus1989">{{cite book|last1=Lucas|first1=S.G.|last2=Sobus|first2=J.C.|year=1989|chapter=The Systematics of Indricotheres|editor-last=Prothero|editor-first=David R.|editor2-last=Schoch|editor2-first=Robert M.|title=The Evolution of Perissodactyls|url=https://archive.org/details/evolutionperisso00prot|url-access=limited|publisher=Oxford University Press|pages=[https://archive.org/details/evolutionperisso00prot/page/n185 358]–378|isbn=978-0-19-506039-3|oclc=19268080}}</ref> </references>

Category:Paraceratheriidae Category:Eocene rhinoceroses Category:Inner Mongolia Category:Oligocene rhinoceroses Category:Hyracodonts Category:Fossil taxa described in 1963