Qufutitan
| Qufutitan | ||||||||||||
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| Temporal occurrence | ||||||||||||
| Middle Eocene ( Sharamurunian ) | ||||||||||||
| 41.1 to 37.7 million years | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Qufutitan | ||||||||||||
| Wang & Wang , 1997 | ||||||||||||
Qufutitan is a now extinct representative of the Brontotherien , a group of unpaired ungulates , whichalso no longer exists, and livedin East Asia in the Middle Eocene around 41 to 38 million years ago. The animal was relatively large, but did not yet have any bony horns typical of later Brontotheria. So far, Qufutitan is only known from a single, incomplete skull.
features
Qufutitan represents a relatively large representative of the Brontotheria, but is largely only known from a partial skull over 50 cm long, which includes the front skull including the entire dentition. The frontal bone was very broad and flat and thus typical of similarly developed Brontotheria, such as Telmatherium . The overall width of the skull is unclear, as the zygomatic arches are only partially preserved. The preserved course of the forehead line shows that the rear, unknown part of the skull was not deeply saddled. Such distinctive cranial saddles are characteristic of the later, horn-bearing Brontotheria. The nasal bone was long and quite wide, but today's downward curve is a result of later deformations in the sediment, so that it was originally rather straight. On the nasal bone there were only small beginnings of bony swellings, so that the animal originally had no real horn formations. The interior of the nose was relatively little expanded and only reached as far as the first premolar . The rostrum had a great length due to the extended upper jaw and middle jaw bone , in connection with the short inner space of the nose, this feature is untypical for more developed Brontotheria. Again, characteristic of this, the orbit was very far forward in the skull and was above the first and second molars .
The upper jaw showed the complete dentition of the early mammals with three incisors , one canine , four premolars and three molars per jaw arch. The incisors were small and spherical in shape and formed a clear arch. The spherical expression is rather untypical for hornless Brontotheria, since such incisors only appeared in the phylloxially younger horn-bearing representatives. The canine, which was over 4 cm long and had a curved shape, turned out to be very massive and large. The subsequent diastema reached a width of 3.5 cm and was therefore moderately large. The molars were generally low-crowned ( brachyodont ), the anterior premolar was only small and square, the other premolars were rectangular. In addition, these were only partially molarized and did not completely resemble the rear molars, which had the W-shaped folded enamel pattern on the chewing surface , which is typical for Brontotheria . The size of the molars increased significantly towards the back, the last molar was over 7 cm long. The entire back row of teeth reached 29.8 cm in length (measured from P1 to M3).
References
The only known find to date was discovered in 1984 in the Huangzhuang Formation near Dong Huangzhuang, 15 km northeast of Qufu in the Chinese province of Shandong . The formation is placed in the late Middle Eocene (locally stratigraphically called Sharamurunian ) and is therefore around 41 to 38 million years old. The skull was one of the first proven fossil finds from this formation, which also contained the remains of other odd ungulates such as Eomoropus or Forstercooperia , but also of pantodons such as Eudinoceras . In addition to the skull of Qufutitan , two remains of the lower jaw from Brontotheria came to light, but they are difficult to classify due to the fragmentation, but their size is comparable to Rhinotitan .
Systematics
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Internal systematics of the Brontotheriini according to Mihlbachler 2008
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The genus Qufutitan belongs to the family of Brontotheriidae (originally Titanotheriidae), a group of mammals from the order of the odd-toed ungulates that is now extinct . According to dental morphological features, the family is considered a distant relative of today's horses . Within the Brontotheriidae, Qufutitan is a member of the subfamily Brontotheriinae and the sub-tribus of the Telmatheriina . Telmatherium and Wickia are closely related genera , both of which have been found in North America . Originally the genus was placed in the subfamily Metatelmatheriinae, which was first introduced in 1943 by Walter W. Granger and William King Gregory and, in addition to Metatelmatherium, included two other polled Asian genera. The subfamily was equated in 1945 with the Telmatheriinae established by Henry Fairfield Osborn in 1929, which in turn included polled North American representatives such as Telmatherium and Sthenodectes . Bryn J. Mader expanded the concept of Telmatheriinae in 1989 to include all Brontotheri with bony horn attachments and later renamed them completely to Brontotheriinae. In a revision of the Brontotherien from 2008, Matthew C. Mihlbachler took up the Telmatheriinae again and shifted them to the rank of sub-tribus. Today they unite all developed Brontotheriina that do not have horn attachments and are opposite to the group of Brontotheriina that show this characteristic.
Qufutitan was first described in 1997 on the basis of the only skull find so far from the Huangzhuang Formation in eastern China ( holotype specimen number: IVPP V8067). The only recognized species is Q. zhoui . The generic name Qufutitan is composed on the one hand from the name of the find area and on the other hand from the Greek word τιτάν ( titan "titanium" or "giant"). The species name zhoui honors the Chinese vertebrate specialist Zhou Mingzhen .
Individual evidence
- ↑ a b c d Matthew C. Mihlbachler: Species taxonomy, phylogeny, and biogeography of the Brontotheriidae (Mammalia: Perissodactyla). Bulletin of the American Museum of Natural History 311, 2008, ISSN 0003-0090 , pp. 1-475
- ↑ a b c d e Wang Yuan and Wang Jinweng: A new brontothere from late middle Eocene of Qufu, Shandong. Vertebrata Palasiatica 35 (1), 1997, pp. 68-77
- ↑ Sha Yexue and Wang Jingwen: The first discovery of Late Eocene locality of Mammalian fauna in East China. Vertebrata Palasiatica 23 (4), 1985, pp. 295-300
- ↑ Shi Ronglin: Late Eocene Mammalian fauna of Huangzhuang, Qufu, Shandong. Vertebrata Palasiatica 27 (2), 1989, pp. 87-101
- ^ Walter W. Granger and William K. Gregory: A revision of zhe Mongolian Titanotheres. Bulletin of the American Museum of Natural History 80, 1943, pp. 349-389
- ↑ Bryn J. Mader: Brontotheriidae: A systematic revision and preliminary phylogeny of North American genera. In: Donald R. Prothero and Robert M. Schoch (Eds.): The evolution of perissodactyls. New York and London, 1989, pp. 458-484
- ↑ Bryn J. Mader: Brontotheriidae In: Christine M Janus, Kathleen M Scott and Louis L Jacobs (eds.): Evolution of Tertiary mammals from North America, Vol. 1. Cambridge 1998, pp. 525-536