Omeisaurus

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Omeisaurus
Skeletal reconstruction of Omeisaurus tianfuensis in Hong Kong.

Skeleton reconstruction of Omeisaurus tianfuensis in Hong Kong.

Temporal occurrence
Middle Jurassic ( Bathonian to Callovian )
168.3 to 163.5 million years
Locations
Systematics
Dinosaur (dinosauria)
Lizard dinosaur (Saurischia)
Sauropods (Sauropoda)
Eusauropoda
Omeisaurus
Scientific name
Omeisaurus
Young , 1939
Omeisaurus skeleton cast in the Miami Museum of Science .

Omeisaurus is a genus of dinosaurs from the group of sauropods , whose fossils come from the Central Jurassic of China . Characteristic of this sauropod was a relatively extremely long neck, which was one of the longest of all sauropods. Thanks to numerous finds, the skeleton of this genus is almost completely known, making it one of the best surviving sauropods - a full description of the skeleton is still pending. In addition to the type Omeisaurus junghsiensis , six other species have been described, of which only three are currently recognized.

The name Omeisaurus ( Chinese. Omei or Emei , Greek saurus - "lizard") points to the Emei Shan , one of the four holy Buddhist mountains in China, which rises about 100 kilometers west of the site of the first skeleton.

features

Omeisaurus was a medium to large-sized sauropod. The type species , Omeisaurus junghsiensis , reached body lengths of about 10 to 15 meters; the species Omeisaurus tianfuensis became larger and measured between 16 and 20 meters. Weight estimates of Omeisaurus tianfuensis vary between 9.8 and 11.8 tons, depending on the study.

The blueprint of this sauropod was characterized by a relatively short trunk and short legs as well as a relatively extremely long neck, which in Omeisaurus junghsiensis measured a length of about 8.5 meters. This made the neck one of the proportionally longest of all sauropods. The cervical spine consisted of 16 to 17 cervical vertebrae, with the individual cervical vertebrae being greatly elongated - the middle cervical vertebrae were almost five times as long as they were deep. The vertebral column consisted of 12 vertebrae, the sacrum of 4 sacral vertebrae fused together; the tail spine, on the other hand, is not fully known. In contrast to Mamenchisaurus , all of the spinous processes were not bifurcated, the spinous processes of the cervical vertebrae were very low. From the 16th or 17th caudal vertebrae, forked chevron bones are found . It is unclear whether Omeisaurus had a club-like ossification at the end of the tail, as it is known from the contemporary Shunosaurus : Although such tail clubs were attributed to Omeisaurus , they were not found in direct connection with the skeletons.

The skull is similar to that of Shunosaurus , but is shorter and taller. The jaws had 4 teeth on each side in the intermaxillary bone, 11 teeth in the upper jaw and 13 to 15 teeth in the lower jaw. The spatulate teeth were proportionally much larger than those of Shunosaurus .

Systematics and types

Omeisaurus is considered to be an original representative of the Eusauropoda , but the exact relationships of this genus are disputed. Many researchers suspect a closer relationship with the also very long-necked Mamenchisaurus and summarize both genera in a group called Mamenchisauridae ; occasionally this grouping is also referred to as Omeisauridae or Euhelopodidae . Other researchers suspect, however, that Omeisaurus and Mamenchisaurus split off independently from the lineage of the more advanced sauropods (the Neosauropoda ).

Although about seven different species have been described so far, only two are known from complete finds and generally recognized as valid - the type species Omeisaurus junghsiensis and the larger species Omeisaurus tianfuensis . Two other species, Omeisaurus maoianus and Omeisaurus jiaoi , were not scientifically described until 2001 and 2011, respectively, both species are based on almost complete skeletons. Three other species, Omeisaurus changshouensis , Omeisaurus luoquanensis and Omeisaurus fuxiensis , on the other hand, are only known from fragmentary remains and are probably invalid. Omeisaurus fuxiensis is sometimes considered a separate genus - Zigongosaurus - or classified as a species of Mamenchisaurus . In 2020, a Chinese research group described Omeisaurus puxiani , from which vertebral bones and extremities were found.

Research history

The first skeleton was discovered in 1936 in Rong County , Zigong , and was recovered that summer by paleontologists Yang Zhongjian (also known as CC Young) and Charles Camp . The fossils, some of which were still surrounded by rock, weighed a total of 2.3 tons and had to be transported in 24 boxes by coolies to the nearest road, about 200 Li (approx. 100 km) away. The fossils were then prepared in the Cenozoic Research Laboratory in Beijing and scientifically described by Yang Zhongjian in 1939 as a new species and genus, Omeisaurus junghsiensis .

Since then, other skeletons and species have been described. The second well-known species, Omeisaurus tianfuensis , was described in 1984 by researchers working with He Xinlu on the basis of an incomplete skeleton that was discovered at Dashanpu near Zigong , about 40 kilometers east of the Omeisaurus junghsiensis site. These researchers mentioned about 10 other skeletons that are believed to be related to this species as well. He Xinlu (1988) imagined Omeisaurus as a rather slow animal that perhaps lived aquatic life. This researcher also saw a mass collection of Omeisaurus fossils in a very small space as an indication of a possible herd life.

In the more recent past the species Omeisaurus maoianus and Omeisaurus jiaoi have been described. The former is based on a skeleton discovered in Jingyan County in Leshan , while the latter is known from a skeleton discovered in Zigong. In 2020 the species Omeisaurus puxiani was described, the fossil material of which was found in Yunyang , China .

Individual evidence

  1. ↑ a b c d Paul Upchurch , Paul M. Barrett , Peter Dodson : Sauropoda. 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. 259-324, here pp. 262, 297 and 301.
  2. ^ A b c John S. McIntosh: Sauropoda. In: David B. Weishampel, Peter Dodson, Halszka Osmólska (eds.): The Dinosauria . University of California Press, Berkeley CA et al. 1990, ISBN 0-520-06726-6 , pp. 345-401, here p. 380.
  3. ↑ CC Young : On a New Sauropoda, with Notes on Other Fragmentary Reptiles from Szechuan. In: Bulletin of the Geological Society of China. Vol. 19, No. 3, 1939, ISSN  1000-9515 , pp. 279-315, here pp. 309-310, doi : 10.1111 / j.1755-6724.1939.mp19003005.x .
  4. ↑ Zhiming Dong , Shiwu Zhou, Yihong Zhang: Dinosaurs from the Jurassic of Sichuan. In: Palaeontologica Sinica. No. 162 = New Series C, No. 23, 1983, pp. 1–136, (PDF; 2.79 MB) .
  5. ↑ a b c Donald F. Glut : Omeisaurus. In: Donald F. Glut: Dinosaurs. The Encyclopedia. McFarland & Company, Jefferson NC et al. 1997, ISBN 0-89950-917-7 , pp. 635-639.
  6. ↑ P. Martin Sander , Andreas Christian, Marcus Clauss, Regina Fechner, Carole T. Gee, Eva-Maria Griebeler, Hanns-Christian Gunga , Jürgen Hummel, Heinrich Mallison, Steven F. Perry, Holger Preuschoft, Oliver WM Rauhut , Kristian Remes , Thomas Tütken, Oliver Wings, Ulrich Witzel: Biology of the sauropod dinosaurs: the evolution of gigantism. In: Biological Reviews. Vol. 86, No. 1, 2011, ISSN  0006-3231 , pp. 117-155, doi : 10.1111 / j.1469-185X.2010.00137.x .
  7. ↑ Philip Senter: Necks for sex: sexual selection as an explanation for sauropod dinosaur neck elongation. In: Journal of Zoology . Vol. 271, No. 1, 2007, pp. 45-53, doi : 10.1111 / j.1469-7998.2006.00197.x .
  8. ↑ a b c d Jeffrey A. Wilson, Paul C. Sereno : Early Evolution and Higher-level Phylogeny of Sauropod Dinosaurs (= Journal of Vertebrate Paleontology. Vol. 18, Supplement to No. 2 = Society of Vertebrate Paleontology. Memoir. Vol . 5, ISSN  1062-161X ). Society of Vertebrate Paleontology, Chicago IL 1998, p. 15.
  9. ↑ P. Martin Sander, Andreas Christian, Marcus Clauss, Regina Fechner, Carole T. Gee, Eva-Maria Griebeler, Hanns-Christian Gunga, Jürgen Hummel, Heinrich Mallison, Steven F. Perry, Holger Preuschoft, Oliver WM Rauhut, Kristian Remes , Thomas Tütken, Oliver Wings, Ulrich Witzel: Biology of the sauropod dinosaurs: the evolution of gigantism. In: Biological Reviews. Vol. 86, No. 1, 2011, pp. 117–155, here p. 10, doi : 10.1111 / j.1469-185X.2010.00137.x .
  10. ↑ a b c Shan Jiang, Fei Li, Guang-Zhao Peng, Yong Ye: A new species of Omeisaurus from the Middle Jurassic of Zigong, Sichuan. In: Vertebrata PalAsiatica. Vol. 49, No. 2, 2011, ISSN  1000-3118 , pp. 185-194, digitized version (PDF; 616.32 kB) .
  11. ^ Ronan Allain, Najat Aquesbi: Anatomy and phylogenetic relationships of Tazoudasaurus naimi (Dinosauria, Sauropoda) from the late Early Jurassic of Morocco. In: Geodiversitas. Vol. 30, No. 2, 2008, ISSN  1280-9659 , pp. 345-424, here p. 403, online .
  12. ↑ Junchang Lü, Shaoxue Li, Qiang Ji, Guofu Wang, Jiahua Zhang, Zhiming Dong: New Eusauropod Dinosaur from Yuanmou of Yunnan Province, China. In: Acta Geologica Sinica. English edition. Vol. 80, No. 1, 2006, ISSN  1000-9515 , pp. 1-10, here p. 9, doi : 10.1111 / j.1755-6724.2006.tb00788.x .
  13. ↑ Omeisaurus Taxonomy. In: The Paleobiology Database. Retrieved August 16, 2014 .
  14. ↑ a b c Feng Tang, Xin-Sheng Jin, X.-M. Kang, G.-J. Zhang: Omeisaurus maoianus: a complete Sauropoda from Jingyan, Sichuan (= Research Works of Natural Museum of Zehjiang. ). China Ocean Press, Beijing 2001, ISBN 7-5027-5382-6 .
  15. ↑ a b Chao Tan; Ming Xiao; Hui Dai; Xu-Feng Hu; Ning Li; Qing-Yu Ma; Zhao-Ying Wei; Hai-dong Yu; Can Xiong; Guang-Zhao Peng; Shan Jiang; Xin-Xin Ren; Hai-Lu You (2020). "A new species of Omeisaurus (Dinosauria: Sauropoda) from the Middle Jurassic of Yunyang, Chongqing, China fauna". Historical Biology: An International Journal of Paleobiology . in press. doi: 10.1080 / 08912963.2020.1743286 .
  16. ↑ CC Young: On a New Sauropoda, with Notes on Other Fragmentary Reptiles from Szechuan. In: Bulletin of the Geological Society of China. Vol. 19, No. 3, 1939, pp. 279-315, here pp. 279-261, doi : 10.1111 / j.1755-6724.1939.mp19003005.x .
  17. ↑ a b Xinlu He, Kui Li, Kaiji Cai, Yuhui Gao: Omeisaurus tianfuensis - a new species of Omeisaurus from Dashanpu, Zigong, Sichuan. In: Journal of Chengdu College of Geology. Supplement 2, 1984, ISSN  0256-2197 , pp. 31-32.

Web links

Commons : Omeisaurus  - collection of images, videos and audio files