Urtinotherium

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Urtinotherium
Temporal occurrence
Upper Eocene to Lower Oligocene
37 to 30 million years
Locations
  • East Asia: northern China, Mongolia
  • Central Asia: Kazakhstan
  • Southeast Europe: Romania
Systematics
Mammals (mammalia)
Higher mammals (Eutheria)
Laurasiatheria
Unpaired ungulate (Perissodactyla)
Indricotheriidae
Urtinotherium
Scientific name
Urtinotherium
Chow & Chiu , 1963

Urtinotherium is an extinct genus from the also extinct family of the Indricotheriidae , which was closely related to today's rhinos and sometimes developed huge forms. The genus lived from the late Eocene to the middle Oligocene about 37 to 30 million years ago and was distributed over East and Central Asia, individual finds also come from southeastern Europe . Overall, however, a few finds are known, described was urtinotherium in 1963 by Chow Minna and Chiu Chan Siang basis of a complete lower jaw from the Inner Mongolia . Urtinotherium did not quite reach the enormous proportions of Paraceratherium , the largest known land mammal, but is closely related to it.

features

Urtinotherium was a large representative of the Indricotheriidae and almost reached the size of Paraceratherium . It is known from a few finds from East and Central Asia or Southeastern Europe ; a comprehensive skeleton is not available. The holotype (copy number IVPP V.2769) includes a complete lower jaw . This was 72 cm long and thus had a slightly shorter length than that of Paraceratherium , which measured a total of 83 cm in large specimens. It had a wedge-like shape and was very elongated, the body of the lower jaw had only a relatively small height, which was 14.2 cm behind the third molar . The symphysis was massive and extended to the beginning of the second premolar . The joint ends protruded up to 35.4 cm. The lower jaw had the complete dentition of early mammals. As a result, the front dentition consisted of three incisors and one canine . The inner pair of incisors was directed forward and significantly enlarged with a crown length of 4.9 cm so that it had a dagger-like shape. The other incisors and the canine, however, were noticeably smaller. There was a small gap between each tooth, similar to its ancestral older relative Juxia . Due to the structure of the anterior dentition, the inner, elongated incisor can be seen as the only functional tooth here. The posterior dentition, which was separated from the anterior by a likewise small diastema , comprised four premolars and three molars. These were similar in structure to those of Paraceratherium with small vomahl and large molars. The latter were clearly low-crowned and had only a little folded enamel . The size of the teeth increased towards the rear, the third molar represented the largest tooth with a length of 7.9 cm and a width of 5.3 cm. The entire length of the row of teeth was 33 cm, the three rear molar teeth took up 61% of this .

Fossil finds

Remains of Urtinotherium come mainly from East and Central Asia, but mostly only jaw fragments and isolated teeth are present, and postcranial skeletal elements are rare . They date to the Upper Eocene and Lower Oligocene and are between 37 and 30 million years old. The holotype mandible was found in the Urtyn obo formation of the early to mid-Oligocene in Inner Mongolia ( China ) in the late 1950s . Finds from the Chinese province of Yunnan are also significant . For example, some isolated upper jaw teeth, which are placed in the Lower Oligocene, come from the Lunan pelvis , as well as other molars of the upper jaw from Qujing and possibly also an isolated upper second molar and individual hand and foot bones such as a metacarpal and an ankle bone from Loping . In addition, finds came to light in the late Eocene deposits of Khoer-Dzam in Mongolia . In addition, finds in the form of isolated outer and inner incisors and rear molars of the lower jaw from Aksyir svita in the Lake Saissan basin in eastern Kazakhstan , which also have a lateocene age, were discovered. Urtinotherium probably reached its westernmost distribution area in south-eastern Europe , where it was detected in the early Oligocene Mera formation near Fildu de Jos in the Sălaj district in Romania . From here comes from the lower section of the formation an approximately 30 cm long fragment of the tibia , which is generally assigned to Urtinotherium due to its age and size, which is in the lower range of variation of Paraceratherium .

Systematics

Internal systematics of the family of the Indricotheriidae according to Wang et al. 2016
 Indricotheriidae 


 Pappaceras


   

 Forstercooperia



   

 Juxia


   

 Urtinotherium


   

 Paraceratherium





Template: Klade / Maintenance / Style

Urtinotherium is a genus from the extinct family of the Indricotheriidae within the superfamily of the Rhinocerotoidea . The Indricotheria are thus closely related to today's rhinos . The Indricotheriidae differ from these by the lack of horn formation on the nose. Other anatomical differences include the front teeth. The Indricotheria have short, conical incisors, from which a pair of large dagger-like incisors develop in the upper and lower jaw in more recent forms. Rhinos, on the other hand, are characterized by only one dagger-like pair in the lower jaw and by chisel-like incisors in the upper dentition. The genus Urtinotherium represents next to Paraceratherium one of the more modern forms of the Indricotherium and developed in the late Eocene . Presumably it goes back to Juxia from the Middle Eocene of northern China, with whom it shares the complete mammalian dentition of the lower jaw. The differences are the significantly larger physique and the greater specialization of the front dentition in Urtinotherium combined with the size reduction of the two outer pairs of incisors. Paraceratherium , the largest land mammal known to date , later developed from Urtinotherium . Compared to Urtinotherium, this has a significantly reduced set of teeth with only one pair of incisors in the lower jaw and the loss of the canine and the anterior premolar. The most recent finds of this large rhinoceros come from the Middle Oligocene.

The first description of urtinotherium was in 1963 by Chow Minna and Chiu Chan-siang basis of the mandible from the Urtyn-Obo formation, in 1959 during a Sino- Soviet was discovered expedition. It is one of the best preserved lower jaws of the Indricotheria. The authors named U. incisivum as a species . The generic name is made up of the name for the site of the same name and the Greek word θηρίον ( thērion ) for "animal". The species poor refers to the elongated incisors ( lat. Dens incisivus ). The first remains to be found date back to 1958 and were discovered in the Lunan Basin in Yunnan, but at that time Chow Minchen classified them as Indricotherium parvum . The description was based on several upper jaw teeth, the small size of which is alluded to by the specific epithet taken from Latin (from parvus for "small"). Due to the little molarized front molar teeth and the clearly low tooth crowns, the first description of the species saw the species as particularly originally within the genus Indricotherium (today Paraceratherium ). In 1989 Indricotherium parvum was synonymous with U. incisivum , as was Indricotherium qujingensis , whose name from 1978 is based on isolated upper molars from Qujing , also Yunnan, which differ only slightly in size from those of Indricotherium parvum . Some scientists suggested in 2007 that Indricotherium parvum was introduced before Urtinotherium incisivum . Following the priority rule of the zoological nomenclature, the type species should therefore be Urtinotherium parvum .

In addition to the type species, U. intermedium is occasionally listed as an independent species. Their description comes from Chiu Chan-siang under the name Indricotherium intermedium from 1962 with reference to an upper molar and a metacarpal bone from Loping in eastern Yunnan. In some cases, Turpanotherium is also seen as identical to Urtinotherium . This genus is based on Indricotherium yagouense , a smaller representative of the late Indricotheria, which is characterized by higher-crowned molars and the absence of the upper incisors. The description was made in 2004 by Chiu Chan-siang and research colleagues on the basis of a complete skull without a lower jaw, which was discovered in the lower part of the Jaozigou Formation near Yagou in the Linxia Basin in the Chinese province of Gansu . The age of the finds there is given as the Upper Oligocene. The hochkronigen molars of Indricotherium yagouense led Chiu and his colleagues Wang Ban Yue in 2007 to the new genus Turpanotherium introduce, in addition, they established then there are the new way Turpanotherium elegans , of a jaw and some limb bones from the Turpan Depression underlies . In 2013 Donald R. Prothero temporarily synonymized Turpanotherium with Urtinotherium due to almost identical molar sizes , but at the same time referred to the need for new studies to be carried out.

literature

  • Zhan-Xiang Qiu and Ban-Yue Wang: Paracerathere fossils of China. Palaeontologia Sinica 193 (New Series C, 29), 2007, pp. 1–396 (pp. 247–386 in English)
  • Donald R. Prothero: Rhino giants: The palaeobiology of Indricotheres. Indiana University Press, 2013, pp. 1-141 (p. 81) ISBN 978-0-253-00819-0

Individual evidence

  1. ↑ Demberelyin Dashzeveg: A new Hyracodontid (Perissodactyla, Rhinocerotoidea) from the Ergilin Dzo formation (Oligocene Quarry 1) in Dzamyn Ude, Eastern Gobi Desert, Mongolia. American Museum Novitates 3178, 1996, pp. 1-12
  2. ↑ a b c Chow Minchen and Chiu Chan-Siang: New genus of giant rhinoceros from oligocene of inner Mongolia. Vertebrata Palasiatica 7 (3), 1963, pp. 230-239
  3. ^ Qi Tao: A new species of Dzungariotherium (Perissodactyla, Mammalia). Vertebrata Palasiatica 27 (4), 1989, pp. 301-305
  4. ↑ a b Chow Minchen: Some Oligocene mammals from Lunan, Yunnan. Vertebrata Palasiatica 2 (4), 1958, pp. 263-267
  5. ↑ Chow Minchen, Chang Yu-Ping and Ting Su-Yin: Some Early Tertiary Perissodactyla from from Lunan Basin, E. Yunnan. Vertebrata Palasiatica 12 (4), 1974, pp. 262-273
  6. ↑ Chow Minchen and Xu Yu-xuan: Indricotherium from Hami basin, Sinkiang. Vertebrata Palasiatica 3 (2), 1959, pp. 93-96
  7. ↑ a b Chiu Chan-Siang: Giant rhinoceros from Loping, Yunnan, and discussion on the taxonomic characters of Indricotherium grangeri. Vertebrata Palasiatica 6 (1), 1962, pp. 57-71
  8. ↑ Bolat Uapovich Bayshashov and Spencer George Lucas: The giant rhinoceros Urtinotherium from the Upper Eocene of the Zaisan basin, Kazakhstan. Selevinia (Kazakhstansky zoologichesky churnal - The Zoological Journal of Kazakhstan) 1-4, 2001, pp. 185-187.
  9. ↑ Vlad A. Codrea and Nicolae Şuraru: New remains of indricotheriin (Perissodactyla, Mammalia) in the Lower Oligocene at Fildu de Jos (Sălaj District, Nw Transylvania). Romanian Journal of Paleontology 76, 1995, pp. 81-87
  10. ↑ Vlad A. Codrea: Rinoceri și Tapiri Terțiari din România. Presa Universitara Clujeana, Cluj-Napoca, 2000, French abstract pp. 145-147
  11. ↑ Haibing Wang, Bin Bai, Jin Meng and Yuanqing Wang: Earliest known unequivocal rhinocerotoid sheds new light on the origin of Giant Rhinos and phylogeny of early rhinocerotoids. Scientific Reports 6, 2016, p. 39607 doi: 10.1038 / srep39607
  12. ^ Leonard B. Radinsky: The families of the Rhinocerotoidea (Mammalia, Perissodactyla). Journal of Mammalogy 47 (4), 1966, pp. 631-639
  13. ^ Leonard B. Radinsky: A review of the Rhinocerotoid Family Hyracodontidae (Perissodactyla). Bulletin of the American Museum of Natural History 136 (1), 1967, pp. 1-47
  14. ↑ Chow Minchen and Chiu Chan-Siang: An eocene giant rhinoceros. Vertebrata Palasiatica 8 (3), 1964, pp. 264-268
  15. ↑ Donald R. Prothero, Earl Manning and C. Bruce Hanson: The phylogeny of the Rhinocerotoidea (Mammalia, Perissodactyla). Zoological Journal of the Linnean Society 87, 1986, pp. 341-366
  16. ^ A b Donald R. Prothero: Rhino giants: The palaeobiology of Indricotheres. Indiana University Press, 2013, pp. 1-141 (p. 81) ISBN 978-0-253-00819-0
  17. ^ Spencer George Lucas and Jay C. Sobus: The systematics of Indricotheres. In: Donald R. Prothero and R. Schoch (Eds.): The evolution of Perissodactyls. New York, Oxford Univ. Press., 1989, pp. 358-378
  18. ^ A b c Zhan-Xiang Qiu and Ban-Yue Wang: Paracerathere fossils of China. Palaeontologia Sinica 193 (New Series C, 29), 2007, pp. 1–396 (pp. 247–386 in English)
  19. ↑ Wang Hai-Bing, Bai Bin, Gao Feng, Huang Wang-Chong and Wang Yuan-Qing: New eggysodontid (Mammalia, Perissodactyla) material from the Paleogene of the Guangnan Basin, Yunnan Province, China. Vertebrata Palasiatica 51 (4), 2013, pp. 305-320
  20. ↑ Qiu Zhan-Xiang, Wang Ban-Yue and Deng Tao: Indricotheres (Perissodactyla, Mammalia) from Oligocene in Linxia Basin, Gansu, China. Vertebrata Palasiatica 42 (3), 2004, pp. 177-192
  21. ↑ Deng Tao, Qiu Zhan-Xiang, Wang Ban-Yue, Wang Xiao-Ming and Hou Su-Kuan: Late Cenozoic biostratigraphy of the Linxia Basin, Northwestern China. In: Wang Xiaoming, Lawrence J. Flynn and Mikael Fortelius (Eds.): Fossil Mammals of Asia. Neogene biostratigraphy and chronology. Columbia University Press, New York, 2013, pp. 243-270

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