Indricotheriidae

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Indricotheriidae
Live reconstruction of Paraceratherium

Live reconstruction of Paraceratherium

Temporal occurrence
Lower Eocene ( Ypresian ) to early Miocene ( Aquitanium )
52 to 20.44 million years
Locations
  • Asia (West, Central, South and East Asia)
  • Europe (Southeast Europe)
Systematics
Mammals (mammalia)
Higher mammals (Eutheria)
Laurasiatheria
Unpaired ungulate (Perissodactyla)
Rhinocerotoidea
Indricotheriidae
Scientific name
Indricotheriidae
Borissiak , 1923

The Indricotheriidae are an extinct family closely related to the rhinoceros . Its members lived from the Middle Eocene to the Lower Miocene 48 to 20 million years ago. Mainly the representatives were widespread in Asia , some later also occurred in Southeast Europe . They are closely related to the rhinos and with Paraceratherium they represent the largest known land mammal in geological history .

features

Skull of Paraceratherium

The Indricotheriidae (Indricotherien) include medium-sized to very large animals. Early representatives in particular were relatively small and reached the size of today's ponies , as was the case with Forstercooperia . Later representatives such as Urtinotherium and Paraceratherium, however, developed huge forms, so some representatives of Paraceratherium with a head-trunk length of sometimes over 8 m and a body weight of around 15 to 20 t were the largest known land mammals in geological history to this day. Their physique was characteristic with a relatively long neck and also long limbs , each ending in three toes, although ancestral older forms had an additional toe on the forefoot, which was later lost. Despite the sometimes extremely high body weight, there was hardly any adaptation to a rather clumsy gait comparable to elephants in the whole body structure . The limbs generally had quite long metapodia , and the forelegs in particular gave further indications of the descent of relatively good runners, as the humerus was rather short compared to the spoke , which is a clear difference to the closely related rhinos. The skull was again quite small in relation to the body proportions, which is also in contrast to the rhinos with their large heads. This had a rather elongated and rather flat shape. Some slight bony elevations, especially in the facial area, served as muscle attachment points and suggest that the Indricotheria representatives had a highly flexible upper lip, which probably resembled the short trunk of today's tapirs.

For the original representatives, the dentition comprised the complete dentition of modern mammals , consisting of three incisors , one canine , four premolars and three molars per jaw arch. Tribal historically younger representatives mainly reduced their front teeth, so that some species only had one incisor per jaw branch. The dagger-like shape of the second upper (I2) and first lower incisor (I1), which were significantly enlarged in later genera and thus resembled small tusks, is significant . The molars had a bilophodontic structure, that is, characterized by two transverse enamel cusps , and usually had low crowns.

Systematics

Internal systematics of the rhinocerotoid according to Wang et al. 2016
 Rhinocerotoidea  

 Hyracodontidae (†) 


   


 Amynodontidae (†) 


   

 Indricotheriidae (= Paraceratheriidae †) 



   

 Eggysodontidae (†) 


   

 Rhinocerotidae 





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The Indricotheriidae represent a family within the superfamily of the Rhinocerotoidea . They are among the closest fossil relatives of today's rhinos . The distinctive features of the two families are the characteristics of the upper and lower incisors. While the Indricotheriidae each have a dagger-like pair of incisors in the upper and lower row of teeth, the rhinos only have one in the lower jaw, while the upper ones are shaped like chisels (so-called "chisel-tusk formation"). The also extinct families of the Amynodontidae , Eggysodontidae and Hyracodontidae belong to the further close relationship within the Rhinocerotoidea .

The name Indricotheriidae was introduced by the Russian-Soviet paleontologist Alexej Alexejewitsch Borissiak (1872-1944) in 1923, initially under the name Indricotheriinae as a subfamily of rhinos, in 1939 he raised them to family level. The names Baluchitheriinae and Paraceratheriinae, also proposed by the US geologist Henry Fairfield Osborn (1857-1935) in 1923, were in use for a while, but are invalid. The name "Indric" after Borissiak referred to a mythical creature from the Book of Doves ( Russian : Голубиная книга ), a work of Slavic folk literature whose beginnings go back to the 13th century and in which "Indric" as the "father of Animals ”. M. Pavlova, on the other hand, attributes “Indric” etymologically to the name Heinrich and locates its origin in Bohemia .

Originally the Indricotheriidae were regarded by most experts as a member of the rhinoceros, the differences already mentioned prompted Leonard Radinsky to assign this subfamily to the Hyracodontidae in 1966 and 1967, which was welcomed by the majority. Some researchers see this critically and refer to the formation of a fourth toe on the forefoot in ancestral older Indricotheria representatives, which could be seen as an indication of a position within the rhinos. However, since this feature occurs in numerous basal rhinoceros (Rhinocerotoidea), this is usually rejected.

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


 Pappaceras


   

 Forstercooperia



   

 Juxia


   

 Urtinotherium


   

 Paraceratherium





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Numerous genera have been described within the family, five are generally recognized today:

The originally described genus Baluchitherium (1913) (ie S. Baluchitherium grangeri Osborn, 1923) was recognized by Vera Gromova in 1959 in her general revision of the Indricotherium as a synonym of Indricotherium (1915). In the same study, the researcher assigned Aralotherium (1939) to the Paraceratherium described in 1911 (including the smaller Baluchitherium osborni Forster Cooper 1913). The Dzungariotherium discovered in 1973 and Indricotherium were in turn understood in a further revision in 1989 as synonyms of Paraceratherium . The study sees the differences in size between the giant Indricotherium and the smaller Paraceratherium , some of which are heavily discussed in science , but also the higher number of incisors in Indricotherium and Dzungariotherium, as well as the clear morphological differences in teeth and teeth as intraspecific sexual dimorphism of the individual Paraceratherium species, which is true is often rejected. The study also equated the rather small- stature Pappaceras , described in 1963, with Forstercooperia . A total of four genres remained in the family after this last overall treatment. However, since 2016 , Pappaceras has been considered independent again, so that the family now contains five genera. There are also problems with the location of the relatively small Benaratherium , described by L. Gabunia in 1955 , which lived in the Oligocene and so far comprised only a few fossil remains. In the 1989 revision, this genus was classified as difficult to classify, a closer relationship with Urtinotherium might come into question, but more recent finds from Mongolia could possibly help to further clarify the taxonomic status.

Tribal history

The first representatives of the Indricotherien appeared with Pappaceras and Forstercooperia in the late Lower and Middle Eocene and are proven from Mongolia . Originally it was assumed that this genus was also native to North America with Forstercooperia grandis , but later investigations assigned this species to the newly described genus Uintaceras with an unclear family status , so that the development of the Indricotheriidae remains limited to Eurasia . The Indricotheria in the Oligocene reached the greatest extent in southeastern Europe . They last appeared in the early Miocene .

Individual evidence

  1. ^ Mikael Fortelius and John Kappelmann: The largest land mammal ever imagined. Zoological Journal of the Linnean Society 107, 1993, pp. 85-101
  2. ^ A b Donald R. Prothero, Claude Guérin and Earl Manning: The history of Rhinocerotoidea. In Donald R. Prothero and RM Schoch (eds.): The evolution of the Perissodactyls. New-York, London, Oxford University Press, 1989, pp. 321-340
  3. ^ A b Walter Granger and William K. Gregory: Further notes on the gigantic extinct rhinoceros, Baluchitherium, from the Oligocene of Mongolia. Bulletin of the American Museum of Natural History 72, 1936, pp. 1-73
  4. ↑ a b c Chow Minchen and Chiu Chan-Siang: An eocene giant rhinoceros. Vertebrata Palasiatica 1964 (8), 1964, pp. 264-268
  5. ^ A b Luke T. Holbrook and Spencer George Lucas: A new genus of rhinocerotoid from the Eocene of Utah and the status of North American "Forstercooperia". Journal of Vertebrate Paleontology 17 (2), 1997, pp. 384-396
  6. ↑ 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
  7. ↑ a b c d e Haibing Wang, Bin Bai, Jin Meng, Yuanqing Wang: Earliest known unequivocal rhinocerotoid sheds new light on the origin of Giant Rhinos and phylogeny of early rhinocerotoids. In: Scientific Reports. 6, 2016, p. 39607 doi: 10.1038 / srep39607 .
  8. ^ Donald R. Prothero and Robert M. Schoch: Classification of the Perissodactyla. In: Donald R. Prothero and Robert M. Schoch (Eds.): The evolution of perissodactyls. New York and London, Clarendon Press and Oxford University Press, 1989, pp. 530-537
  9. ^ Leonard B. Radinsky: The families of the Rhinocerotoidea (Mammalia, Perissodactyla). Journal of Mammalogy 47 (4), 1966, pp. 631-639
  10. ↑ a b Алексей Алексеевич Борисяк: О роде Indricotherium ng (сем. Rhinocerotidae). Записки Российской Академик Наукъ 35 (8), 1923, pp. 1–128
  11. ^ A b Henry Fairfield Osborn: Baluchitherium grangeri, a giant hornless rhinoceros from Mongolia. American Museum Novitates 78, 1923, pp. 1-15
  12. ↑ MV Pavlova: Indricotherium transouralicum n. Sp. provenent you district de Tourgay. Bulletin de la Societe des Naturalistes de Moscou, Section Geologique 31, 1922, pp. 95-116
  13. ^ Leonard B. Radinsky: The families of the Rhinocerotoidea (Mammalia, Perissodactyla). Journal of Mammalogy 47 (4), 1966, pp. 631-639
  14. ↑ 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
  15. ↑ Kurt Heissig: The rhinocerotidae. In: Donald R. Prothero and RM Schoch (eds.): The evolution of perissodactyls. New York, London, Oxford University Press, 1989, pp. 399-417
  16. ↑ Horace Elmer Wood: A primitive rhinoceros from the late eocene of Mongolia. American Museum Novitates 2146, 1963, pp. 1-12
  17. ^ A b Horace Elmer Wood: Cooperia totadentata, a remarkable rhinoceros from the eocene of Mongolia. American Museum Novitates 1012, 1938, pp. 1-22
  18. ↑ Chow Minchen and Chiu Chan-Siang: New genus of giant rhinoceros from oligocene of inner Mongolia. Vertebrata Palasiatica 1963 (9), 1963, pp. 230-239
  19. ↑ Clive Forster-Cooper: Paraceratherium bugtiense, a new genus of Rhinocerotidae from the Bugti Hills of Baluchistan - preliminary notice. The Anals and Magazine of Natural History 8, 1911, pp. 711-716
  20. ↑ Вера Громова: Гигантские носороги. Академия Наук СССР 71, Moscow 1959
  21. ^ A b c 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 University Press, 1989, pp. 358-378
  22. ↑ Ye Jie, Meng Jin and Wu Wen: Discovery of Paraceratherium in the northern Junggar Basin of Xinjiang. Vertebrata Palasiatica 41 (3), 2003, pp. 220-229
  23. ↑ Pierre-Olivier Antoine, Levent Karadenizli, Gerçek Saraç and Sevket Sen: A giant rhinocerotoid (Mammalia, Perissodactyla) from the late Oligocene of north-central Anatolia (Turkey). Zoological Journal of the Linnean Society 152 (3), 2008, pp. 581-592
  24. ↑ Kurt Heissig: Rhinocerotidae (Perissodactyla, Mammalia). In: Gudrun Daxner-Höck (Ed.): Oligocene-Miocene Vertebrates from the Valley of Lakes (Central Mongolia): Morphology, phylogenetic and stratigraphic implications. Annals of the. Naturhistorisches Museum zu Wien 108 A, 2007, pp. 233–269
  25. ^ 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
  26. ↑ Spencer George Lucas, Bolat U. Bayshashov, Lyubov A. Tyut'kova, Ayzhan K. Dzhamangaraeva and Bolat Zh. Aubekerov: Mammalian biochronology of the Paleogene-Neogene boundary at Aktau Mountain, Eastern Kazakhstan. Paläontologische Zeitschrift 71 (3-4), 1997, pp. 305-314