Tarbosaurus

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Tarbosaurus
Reconstructed skeleton in CosmoCaixa, Barcelona

Reconstructed skeleton in CosmoCaixa , Barcelona

Temporal occurrence
Upper Cretaceous ( Maastrichtian )
72 to 66 million years
Locations
Systematics
Lizard dinosaur (Saurischia)
Theropoda
Tyrannosauroidea
Tyrannosauridae
Tyrannosaurinae
Tarbosaurus
Scientific name
Tarbosaurus
Maleev , 1955
Art
  • Tarbosaurus bataar

Tarbosaurus ("terrifying lizard", from ancient Greek τὸ τάρβος, -εος tarbos , German 'horror, fear' and ὁ σαῦρος, σαύρου sauros , German 'lizard' ) is a genus of theropod dinosaur fromthe late Cretaceous family of the Tyrannosaurs ( Maastrichtium )livedin Asia .

Fossils come mainly from Mongolia ( Nemegt formation ), but fragmentary remains have also been discovered in parts of China . Although different species have been named, only one species, the type species Tarbosaurus bataar , is recognized today. Some experts believe Tarbosaurus to be an Asian representative of the North American genus Tyrannosaurus - if so, the genus Tarbosaurus would be invalid.

Tarbosaurus and Tyrannosaurus are considered closely related, although some paleontologists consider the Alioramus, also from Mongolia, to be the closest relative of Tarbosaurus . Like most known tyrannosaurids, Tarbosaurus was a large bipedal carnivore with a large skull and very small, two-fingered arms - the latter were smaller in relation to body size in Tarbosaurus than in any other tyrannosaurid.

Tarbosaurus lived in a flooded area crossed by rivers. In this habitat he was at the top of the food pyramid and likely hunted large dinosaurs such as the hadrosaurids Saurolophus or the sauropod Nemegtosaurus . He is known from dozens of finds, including complete skulls and skeletons, which allowed scientific studies of its phylogeny , brain structure, and skull mechanics.

features

Live reconstruction of Tarbosaurus
Tarbosaurus bataar in size comparison with a human

Tarbosaurus was one of the largest tyrannosaurids and was only slightly smaller than Tyrannosaurus . The largest known individuals were between ten and twelve meters long and had their heads up to five meters above the ground. An estimate of the weight of an adult individual has never been published, but it is believed that the Tarbosaurus was slightly lighter than the Tyrannosaurus .

The largest known Tarbosaurus skull is more than 1.3 meters long, larger than any other tyrannosaurid except Tyrannosaurus . The skull was similar in height to that of the Tyrannosaurus , but not so wide, especially at the back of the head, that the eyes were not directed straight ahead - this suggests that Tarbosaurus, unlike Tyrannosaurus, could not see in three dimensions . There were between 60 and 64 teeth in the jaw; slightly more than with Tyrannosaurus , but less than with smaller tyrannosaurids like Gorgosaurus or Alioramus . While most of the teeth were oval in cross-section, the teeth of the intermaxillary bone (premaxillary) at the front end of the upper jaw had a “D” -shaped cross-section. This heterodontia is characteristic of the entire family. The longest teeth were in the upper jaw and had crowns up to 85 millimeters long . As with Alioramus, the lower jaw was stabilized by a ridge on the outer surface of the angular bone, which was hooked to the back of the dental bone. This mechanism is absent in other tyrannosaurids, whose jaws were therefore more flexible.

Systematics

Tarbosaurus is classified within the Tyrannosauridae family and within the Tyrannosaurinae subfamily . Other members of the Tyrannosaurinae include Tyrannosaurus and the earlier Daspletosaurus from North America, and likely Alioramus from Asia. The Tyrannosaurinae differs from the other subfamily, the Albertosaurinae, by their more robust construction and their proportionally larger skull and longer thigh bones.

Tarbosaurus bataar was originally described as a species of Tyrannosaurus , which has been supported by recent studies. Other scientists prefer to separate both taxa and consider them merely as sister genera. A cladistic analysis from 2003 based on skull features, however, sees Alioramus as the closest relative of Tarbosaurus , since both genera share skull features that were not found in other tyrannosaurins. This theory suggests different lineages in Asia and North America; if it can be proven, a synonymity between Tyrannosaurus and Tarbosaurus would be excluded.

 Tyrannosauridae  
  Albertosaurinae  

 Albertosaurus


   

 Gorgosaurus



  Tyrannosaurinae  

 Daspletosaurus


  NN  

 Alioramus (?)


  NN  

 Tarbosaurus


   

 Tyrannosaurus






Cladogram of the Tyrannosauridae according to Holtz, 2004

 Tyrannosauridae  
  Albertosaurinae  

 Albertosaurus


   

 Gorgosaurus



  Tyrannosaurinae  
  NN  

 Daspletosaurus


  NN  

 Tarbosaurus


   

 Alioramus




  NN  

 Nanotyrannus


   

 Tyrannosaurus





Alternative cladogram of the Tyrannosauridae according to Currie and others 2003

Discovery history and naming

Tarbosaurus foot, South Gobi

In 1946, a joint Soviet- Mongolian expedition discovered a large theropod skull and some vertebrae in the Gobi desert. The site is in the Mongolian Aimag Ömnö-Gobi and, stratigraphically , belongs to the Nemegt formation . These fossils described the Russian paleontologist Evgeny Maleev in 1955 as the type material of a new species, which he Tyrannosaurus bataar called - the Artepitheth bataar is a misspelling of the Mongolian word баатар / baatar and means "hero." In the same year, Maleev described and named three other theropod skulls associated with skeletal material that were discovered by the same expedition in 1948 and 1949. Maleev named the first of these finds (PIN 551-2) Tarbosaurus efremovi , whereby the new genus name Tarbosaurus is derived from the Greek words ταρβος / tarbos (“ fearful ”, “awe”) and σαυρος / sauros (“lizard”) and so much as "fearsome lizard" means. The Artepitheth efremovi honors Ivan Yefremov , a Russian paleontologist and science fiction writer. The other two finds (PIN 553-1 and PIN 552-2) also described Maleev as new species, but placed them in the North American genus Gorgosaurus - each as Gorgosaurus lancinator and Gorgosaurus novojilovi . These last three specimens were smaller than the first specimen described as Tyrannosaurus bataar .

Ömnö-Gobi-Aimag, the Mongolian aimag (province) where most of the Tarbosaurus remains were discovered

In a publication from 1965, Anatoly Roshdestvensky assumes that all four finds described by Maleev belong to the same species and merely represent different stages of development . Since he saw differences to Tyrannosaurus , he set up the new combination Tarbosaurus bataar , which includes both the findings described in 1955 and more recent material. Later authors, including Maleev himself, agreed with Roshdestvensky's analysis, although others used the name Tarbosaurus efremovi instead of Tarbosaurus bataar . The American paleontologist Kenneth Carpenter re- examined the material in 1992 and concluded that it belongs to the genus Tyrannosaurus , as originally assumed by Maleev. Carpenter assigned all known Tarbosaurus finds to the species Tyrannosaurus bataar , except for the remains, which Maleev called Gorgosaurus novojilovi - for this find he described the new genus Maleevosaurus novojilovi . George Olshevsky (1995) established the new genus name Jenghizkhan (after Genghis Khan) for Tyrannosaurus bataar and at the same time considered Tarbosaurus efremovi and Maleevosaurus novojilovi to be valid, which results in a total of three different contemporary tyrannosaurid genera from the Nemegt formation. A study published in 1999 classified Maleevosaurus as a juvenile Tarbosaurus . All publications since 1999 recognize only a single species, which is named either Tarbosaurus bataar or Tyrannosaurus bataar .

After the Russian-Mongolian expeditions in the 1940s, Polish-Mongolian expeditions to the Gobi desert took place from 1963 to 1971 and discovered many new fossils from the Nemegt formation, including new Tarbosaurus finds. Expeditions by Japanese and Mongolian researchers between 1993 and 1998, as well as private expeditions organized by the American paleontologist Phillip Currie at the turn of the 21st century, discovered further Tarbosaurus material. More than 30 finds are known to date, including more than 15 skulls and several complete postcranial skeletons (residual skeletons).

Possible synonyms

Chinese paleontologists discovered a partial skeleton with skull of a small theropod ( IVPP V4878) in the Xinjiang Autonomous Region of China in the mid-1960s. This find from the Subashi Formation was described by Dong Zhiming in 1977 as a new genus and species, Shanshanosaurus huoyanshanensis . Gregory Paul (1988) saw a tyrannosaurid in Shanshanosaurus and assigned it to the genus Aublysodon , which is now considered a noun dubium and is therefore no longer used. Dong and Currie later re-examined the find and considered it to be a juvenile specimen of a larger tyrannosaurid species, but without ascribing the find to a specific species. However, these researchers noted that Tarbosaurus would be a possibility. Over the years, other Chinese sites brought more tyrannosaurid teeth and fragmentary remains to light, some of which have been named. Albertosaurus periculosis , Tyrannosaurus luanchuanensis , Tyrannosaurus turpanensis and Chingkankousaurus fragilis are often synonymous with Tarbosaurus .

Alioramus , which was named by Kurzanov in 1976, is another genus of tyrannosaurids from somewhat older sediments in Mongolia. Some analysis suggests that Alioramus was very closely related to Tarbosaurus . The only specimen found was described as an adult individual; however, the long, low skull is characteristic of juvenile tyrannosaurids. Currie speculated that Alioramus might have beena juvenile Tarbosaurus , but noted that the much larger number of teeth and the row of bony cusps on the top of the skull speak against this hypothesis.

Paleobiology

Like some other tyrannosaurids, Tarbosaurus is also known for a relatively large number of well-preserved finds - in fact, a quarter of all fossils come from the Nemegt formation of Tarbosaurus . Although Tarbosaurus has not been studied as intensively as the North American tyrannosaurids, the available material allows conclusions to be drawn about the biology of this animal.

Skull mechanics

Tarbosaurus skull

The Tarbosaurus skull was first fully described by Hurum and Sabath in 2003. The scientists listed differences between Tarbosaurus and the North American tyrannosaurids, most of which are related to the transmission of stress during a bite. When the upper jaw bites an object, force is transmitted through the maxillary (the primary tooth-bearing bone in the upper jaw) to the surrounding skull bones. In North American tyrannosaurids, the force migrates from the maxillary into the fused, paired nasal bone (nasals) on the top of the skull, which was closely connected to the paired tear bone (lacrimal) on the back by bony struts . These struts closed these bones together, suggesting that the force from the nasal bone was transferred to the tear bone.

Tarbosaurus lacked these struts and the connection between the nasal bone and the tearbone was weak. Instead, a rearward protrusion of the maxillary in Tarbosaurus was very pronounced, which fits into a hollow formed by the tear bone. In North American tyrannosaurids, this protrusion was just a thin, bony plate. The large projection suggests that the force in Tarbosaurus was transferred directly from the maxillary to the tearbone. The tear bone was also closely anchored to the frontal and prefrontal bones; the well-developed connections between the maxillary, lacrimal, frontal and prefrontals have made the entire maxilla more rigid.

Another significant difference between Tarbosaurus and its North American relatives was the more rigid lower jaw. While many theropods, including the North American tyrannosaurids, had a certain degree of flexibility between the bones of the lower jaw, Tarbosaurus had a locking mechanism: For example, a comb sat on the angular bone, which was hooked with a square process on the back of the lower jaw .

Some researchers hypothesized that Tarbosaurus's more rigid skull may have been an adaptation for hunting the large titanosaurs found in the Nemegt Formation but often lacking in Late Cretaceous North America. The differences in the skull mechanics also allow conclusions to be drawn about the relationships between the tyrannosaurids: Tarbosaurus -like connections between skull bones are also known from the Mongolian Alioramus , which suggests that this species, and not Tyrannosaurus , was the closest relative of Tarbosaurus . Similarities between Tarbosaurus and Tyrannosaurus could also be due to their gigantic size and evolved independently through convergent evolution .

Brain structure

Cast of a Tarbosaurus bataar skull

In a Tarbosaurus skull (PIN 553-1), which was discovered by the Soviet-Mongolian expedition in 1948 and originally called Gorgosaurus lancinator , the skull had been preserved - this enables casts of the brain. Maleev made preliminary observations on the shape of a Tarbosaurus brain using a plaster cast ; however, a more recent cast made of polyurethane rubber allowed a more detailed study of brain structure and function.

Another study looked at the Tyrannosaurus rex brain structure , which was very similar to that of Tarbosaurus - the only differences are in the positions of some nerves, such as the trigeminal and accessory nerves . The brains of the tyrannosaurids resembled those of recent crocodiles and other reptiles more than those of birds and were comparatively small; the brain volume of a twelve-meter-long Tarbosaurus is only 184 cubic centimeters. The large olfactory bulbs and the well-developed terminal nerve and olfactory nerve (olfactory nerve) suggest that Tarbosaurus had a good sense of smell, as was the case with Tyrannosaurus . The Jacobson organ was well developed; an olfactory organ that many animals today use primarily to perceive pheromones . This could suggest that Tarbosaurus had complex mating behavior. The vestibulocochlear nerve was also large and shows a strong auditory perception as well as a good sense of coordination and balance. In contrast to this, the nerves and brain structures that were responsible for the sense of sight were smaller and underdeveloped: The roof of the midbrain , which is responsible for processing visual stimuli in reptiles, was very small in Tarbosaurus ; as well as the optic nerve and the oculomotor nerve , which controls eye movements. Unlike Tyrannosaurus , which had forward-facing eyes that allowed three-dimensional vision, Tarbosaurus had a thinner skull with side-facing eyes, as was typical for other tyrannosaurids. All of this suggests that Tarbosaurus relied more on its sense of smell and hearing than its sight.

Paleoecology

Tarbosaurus skeleton in the Geological-Paleontological Museum in Münster

The vast majority of Tarbosaurus fossils come from the Nemegt Formation in southern Mongolia. The age of this geological formation has never been determined radiometrically , but the fauna documented in the fossil record suggests a deposition period during the Maastrichtian (72 to 66 million years ago), the last stage of the Cretaceous period. The Subashi Formation , which contained the Shanshanosaurus remains, was also dated to the Maastrichtian. The sediments of the Nemegt Formation contain remains of flood plains, large rivers and paleo-soils , which suggest a humid climate with periodic droughts - in contrast to the semi-arid environments of the underlying Barun-Goyot Formation and Djadochta Formation . The vertebrate fauna in the water consisted of fish, turtles and crocodiles such as Shamosuchus , which was represented by several species and specialized in cracking mussels. Mammalian fossils are extremely rare in the Nemegt Formation, but many birds are known, such as the Enantiornithe Judinornis , the Hesperornithiforme Gurilynia and the Anseriforme Teviornis . Scientists have also described many dinosaur species from the Nemegt Formation, including ankylosaurs like Tarchia and pachycephalosaurs like Homalocephale and Prenocephale . As by far the largest predators of the time, adult Tarbosaurus probably hunted large hadrosaurs like Saurolophus and Barsboldia or sauropods like Nemegtosaurus and Opisthocoelicaudia . Smaller theropods of the formation include troodontids ( Borogovia , Tochisaurus , Saurornithoides ), oviraptorosaurs ( Elmisaurus , Nemegtomaia , Rinchenia ), or Bagaraatan , which is sometimes classified as a basal tyrannosauroid. Other theropods, such as the gigantic Therizinosaurus , may have been herbivorous , while ornithomimosaurs such as Anserimimus , Gallimimus, and Deinocheirus may have been omnivorous . In the absence of medium-sized predators, juvenile Tarbosaurus may have filled this gap.

Others

The Ambassador of the European Union Andrew Jacobs in the East Timor’s Presidential Palace , with the Tarbosaurus in the background

The skeleton of a Tarbosaurus bataar is exhibited in the Presidential Palace of East Timor . It was excavated by a team from the Australian Monash University in Mongolia and is now on loan in East Timor as a display object for school children.

Individual evidence

  1. ↑ Takanobu Tsuihiji, Mahito Watabe, Khishigjav Tsogtbaatar, Takehisa Tsubamoto, Rinchen Barsbold , Shigeru Suzuki, Andrew H. Leed, Ryan C. Ridgely, Yasuhiro Kawahara, Lawrence M. Witmer : Cranial osteology of a juvenile specimen of Tarbosauridae, Tyrannosauridae ) from the Nemegt Formation (Upper Cretaceous) of Bugin Tsav, Mongolia. In: Journal of Vertebrate Paleontology. Vol. 31, No. 3, 2011, ISSN  0272-4634 , pp. 497-517, doi : 10.1080 / 02724634.2011.557116 .
  2. ↑ a b Евгений А. Малеев: Новый хищный динозавр из верхнего мела Монголии. In: Доклады Академии наук СССР. Vol. 104, No. 5, 1955, ISSN  0002-3264 , pp. 779-783 (In English: New carnivorous dinosaurs from the Upper Cretaceous of Mongolia. Online (PDF; 12.41 KB) ).
  3. ↑ a b c d e f g h i Thomas R. Holtz Jr .: Tyrannosauroidea. In: David B. Weishampel , Peter Dodson , Halszka Osmólska (eds.): The Dinosauria . 2nd edition. University of California Press, Berkeley CA et al. 2004, ISBN 0-520-24209-2 , pp. 111-136.
  4. ↑ a b c d e f g h i j k l Jørn H. Hurum, Karol Sabath: Giant theropod dinosaurs from Asia and North America: Skulls of Tarbosaurus bataar and Tyrannosaurus rex compared . In: Acta Palaeontologica Polonica. Vol. 48, No. 2, 2003, ISSN  0567-7920 , pp. 161-190.
  5. ↑ a b c Thomas D. Carr, Thomas E. Williamson, David R. Schwimmer: A new genus and species of tyrannosauroid from the Late Cretaceous (middle Campanian) Demopolis Formation of Alabama. In: Journal of Vertebrate Paleontology. Vol. 25, No. 1, 2005, pp. 119-143, doi : 10.1671 / 0272-4634 (2005) 025 [0119: ANGASO] 2.0.CO; 2 .
  6. ↑ a b c d e Philip J. Currie , Jørn H. Hurum, Karol Sabath: Skull structure and evolution in tyrannosaurid dinosaurs . In: Acta Palaeontologica Polonica. Vol. 48, No. 2, 2003, pp. 227-234, (PDF; 137 kB).
  7. ↑ a b Евгений А. Малеев: Гигантские хищные динозавры Монголии. In: Доклады Академии наук СССР. Vol. 104, No. 4, 1955, ISSN  0002-3264 , pp. 634-637.
  8. ^ A b Ken Carpenter : Tyrannosaurids (Dinosauria) of Asia and North America. In: Niall J. Mateer, Chen Pei-ji (Eds.): Aspects of Nonmarine Cretaceous Geology. China Ocean Press, Beijing 1992, ISBN 7-5027-1463-4 , pp. 250-268.
  9. ^ Henry George Liddell , Robert Scott : A Lexicon abridged from Liddell and Scott's Greek-English Lexicon. 24th edition, carefully revised throughout. Ginn, Boston 1891 (Reprinted edition. Clarendon Press, Oxford 2010, ISBN 978-0-19-910207-5 ).
  10. ↑ Анатолий К. Рождественский: Возрастная изменчивость и некоторые вопросы систематики динозавров Азии. In: Палеонтологический Журнал. No. 3, 1965, ISSN  0031-031X , pp. 95-109.
  11. ↑ Евгений А. Малеев: Гигантские карнозавры семейства Tyrannosauridae. In: Совместная советско-монгольская палеонтологическая экспедиция. Труды. Vol. 1, 1974, ZDB -ID 751007-x , pp. 132-191.
  12. ↑ Ринченгийн Барсболд: Хищные динозавры мела Монголии. Совместная Советско-Монгольская палеонтологическая экспедиция (= Труды. 19). Наука, Москва 1983, pp. 5–119 (In English: Rinchen Barsbold: Carnivorous dinosaurs from the Cretaceous of Mongolia. The Joint Soviet-Mongolian Paleontological Expedition (= Transaction of the Joint Soviet-Mongolian Paleontological Expedition. Vol. 19). Self-published by the author, Berkeley CA 1983, 5-119, online ).
  13. ↑ George Olshevsky, Tracy L. Ford: The origin and evolution of the tyrannosaurids, part 1. In: Kyoryugaku Saizensen. = Dinosaur Frontline. Vol. 9, 1995, pp. 92-119 (Japanese).
  14. ↑ Thomas D. Carr: Craniofacial ontogeny in Tyrannosauridae (Dinosauria, Coelurosauria). In: Journal of Vertebrate Paleontology. Vol. 19, No. 3, 1999, pp. 497-520, doi : 10.1080 / 02724634.1999.10011161 .
  15. ↑ Xing Xu , Mark A. Norell , Xuewen Kuang, Xiaolin Wang, Qi Zhao, Chengkai Jia: Basal tyrannosauroids from China and evidence for protofeathers in tyrannosauroids. In: Nature . Vol. 431, No. 7009, 2004, pp. 680-684, doi : 10.1038 / nature02855 , PMID 15470426 .
  16. ↑ Masato Watabe, Shigeru Suzuki: Cretaceous fossil localities and a list of fossils collected by the Hayashibara Museum of Natural Sciences and Mongolian Paleontological Center Joint Paleontological Expedition (JMJPE) from 1993 through 1998. In: Hayashibara Museum of Natural Sciences Research Bulletin. Vol. 1, 2000, ISSN  1345-7225 , pp. 99-108.
  17. ^ Philip J. Currie: Nomadic Expeditions, Inc., report of fieldwork in Mongolia, September 2000. In: Alberta Palaeontological Society, Fifth Annual Symposium. Abstract volume. Mount Royal College, Calgary 2001, pp. 12-16.
  18. ^ Philip J. Currie: Report on fieldwork in Mongolia, September 2001. In: Alberta Palaeontological Society, Sixth Annual Symposium, "Fossils 2002". Abstract volume. Mount Royal College, Calgary 2002, pp. 8-12.
  19. ↑ Dong Zhiming : On the dinosaurian remains from Turpan, Xinjiang. In: Vertebrata PalAsiatica. Vol. 15, No. 1, 1977, ISSN  0042-4404 , pp. 59-66, (Chinese).
  20. ^ Gregory S. Paul : Predatory Dinosaurs of the World. A complete and illustrated guide. Simon & Schuster, New York NY et al. 1988, ISBN 0-671-61946-2 .
  21. ↑ Philip J. Currie, Dong Zhiming: New information on Shanshanosaurus huoyanshanensis, a juvenile tyrannosaurid (Theropoda, Dinosauria) from the Late Cretaceous of China. In: Canadian Journal of Earth Sciences. Vol. 38, No. 12, 2001, ISSN  0008-4077 , pp. 1729-1737, doi : 10.1139 / cjes-38-12-1729 .
  22. ↑ Сергей М. Курзанов: Новый позднемеловой карнозавр из Ногон-Цава, Монголия. In: Совместная советско-монгольская палеонтологическая экспедиция. Труды. Vol. 3, 1976, pp. 93-104.
  23. ^ Philip J. Currie, Cranial anatomy of tyrannosaurids from the Late Cretaceous of Alberta . In: Acta Palaeontologica Polonica. Vol. 48, No. 2, 2003, ISSN  0567-7920 , pp. 191-226, (PDF; 1.8 MB).
  24. ↑ a b c Tomasz Jerzykiewicz, Dale Russell: Late Mesozoic stratigraphy and vertebrates of the Gobi Basin. In: Cretaceous Research. Vol. 12, No. 4, 1991, ISSN  0195-6671 , pp. 345-377, doi : 10.1016 / 0195-6671 (91) 90015-5 .
  25. ↑ Евгений А. Малеев: О головном мозге хищных динозавров. In: Палеонтологический Журнал. No. 2, 1965, pp. 141-143.
  26. ↑ a b Sergei V. Saveliev, Vladimir R. Alifanov: A new study of the brain of the predatory dinosaur Tarbosaurus bataar (Theropoda, Tyrannosauridae). In: Paleontological Journal. Vol. 41, No. 3, 2007, ISSN  0031-0301 , pp. 281-289, doi : 10.1134 / S0031030107030070 .
  27. ↑ Christopher A. Brochu: A digitally-rendered endocast for Tyrannosaurus rex. In: Journal of Vertebrate Paleontology. Vol. 20, p. 1, 2000, p. 1-6, doi : 10.1671 / 0272-4634 (2000) 020 [0001: ADREFT] 2.0.CO; 2 .
  28. ^ Felix M. Gradstein, James G. Ogg, Alan G. Smith: A Geologic Time Scale 2004. Cambridge University Press, Cambridge et al. 2004, ISBN 0-521-78673-8 .
  29. ↑ Yanbin Shen, J. Niall Mateer: An outline of the Cretaceous system in northern Xinjiang, western China. In: Niall J. Mateer, Chen Pei-ji (Eds.): Aspects of Nonmarine Cretaceous Geology. China Ocean Press, Beijing 1992, ISBN 7-5027-1463-4 , pp. 49-77.
  30. ^ Halszka Osmólska: Nemegt Formation. In: Philip J. Currie, Kevin Padian (Eds.): Encyclopedia of dinosaurs. Academic Press, San Diego CA et al. 1997, ISBN 0-12-226810-5 , pp. 471-472.
  31. ↑ Михаил Б. Ефимов: Обзор ископаемых крокодилов Монголии. In: Совместная советско-монгольская палеонтологическая экспедиция. Труды. Vol. 24, 1983, pp. 76-95.
  32. ^ Dinosaurs in the Presidential Palace

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