Oviraptorosauria

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Oviraptorosauria
Skeleton of a Citipati

Skeleton of a Citipati

Temporal occurrence
Lower to Upper Cretaceous ( Barremium to Maastrichtian )
130.7 to 66 million years
Locations
Systematics
Dinosaur (dinosauria)
Lizard dinosaur (Saurischia)
Theropoda
Coelurosauria
Maniraptora
Oviraptorosauria
Scientific name
Oviraptorosauria
Barsbold , 1976

The Oviraptorosauria (derived from Latin ovis - "egg"; raptor - "robber" and ancient Greek σαῦρος (saũros) = lizard, reptile) are a group of dinosaurs within the theropods .

They were bipedal , small to medium-sized theropods that varied in size from the turkey -sized caudipteryx to the 8-meter-long gigantoraptor . The short and deep skull had an often toothless beak, which suggests a herbivorous or omnivorous diet. Some genera also showed a conspicuous crest of the skull. Oviraptorosauria were very bird-like in appearance and were believed to be closely related to the ancestors of today's birds - some researchers even suspect that they were actually flightless birds that evolved from flightless ancestors. At least some basic (primitive) genera were pinnate .

Oviraptorosauria can systematically be divided into primitive genera such as Caudipteryx and into the groups Oviraptoridae and Caenagnathidae . Within the theropods they are counted among the Maniraptora , whereby the Therizinosauroidea are regarded as closest relatives. Together with the Therizinosauroidea, the Oviraptorosauria form the taxon Oviraptoriformes .

features

skull

Oviraptorosauria were characterized by a short snout and deep jaws shaped into a beak. The jaws were toothless, but the basal genera Avimimus , Caudipteryx , Protarchaeopteryx and Incisivosaurus showed four teeth in the intermaxillary bone (at the front end of the upper jaw) and sometimes much smaller teeth in the lower and upper jaw. In Caudipteryx , the tooth crowns were needle-like. Incisivosaurus showed pronounced heterodontic dentition: the first tooth on each side of the intermaxillary bone was flattened to an incisor and extremely elongated. The intermaxillary bone was short but very deep and had a notched cutting edge on the underside. The jawbones were probably surrounded by a horny beak .

As with all theropods, the skull showed several skull windows. The antorbital window, a skull window in front of the eye sockets, was short and high. The Caenagnathide Chirostenotes showed an elongated antorbital region, which could mean that some Caenagnathids had a longer skull than Oviraptorids. The nostrils were large and usually elongated in oviraptorids. They were located high up, mostly elliptical and almost vertically aligned. The eye socket (orbit) and the mandibular window in the lower jaw were large. The infratemporal window, a skull window behind the eye socket, was square and about the same size as the eye socket.

Except for Caudipteryx, the cranial bones were heavily pneumatized (had cavities), while Incisivosaurus had at least the nasal , lacrimal and square bones pneumatized. In contrast to other theropods, the parietal bone was at least as long as the frontal bone in the Oviraptorosauria .

In some representatives of the Oviraptoride, different skull bones formed a conspicuous, strongly pneumatized skull crest, which resembled today's cassowaries . Since a skull crest has only been detected on large skulls, it is assumed that, similar to cassowaries, it only developed in adult animals, while it was still missing in young animals ( allometry ).

Trunk skeleton and limbs

Almost complete spinal columns are known from many oviraptorids. The neck was relatively long and showed 1 to 2 cervical vertebrae more than other theropods. Since the tail was short, the neck was strongly “S” -shaped curved in order to carry the head as upright as possible so that the balance could be maintained. A total of 12 to 13 cervical vertebrae were likely present - with the neck being more than twice as long as the skull. In addition, there are 9 to 10 back, 6 to 8 sacrum (synsacrum), and 22 to 32 caudal vertebrae, with the tail being shorter than most other theropods. In Nomingia , Similicaudipteryx Citipati, and Conchoraptor , the last two to four caudal vertebrae were fused into a pygostyle , a feature that is otherwise only known from birds. Probably the tails wore long, ranging tail feathers that the display behavior was or is placed or spread courtship. In the case of the oviraptorids, all vertebrae except for the last caudal vertebrae showed pleurocoeles, which means that the front side was hollowed out. Another characteristic of many Oviraptorosauria were deep pituitary glands, which ran on the front half of the vertebral centers from two to three vertebrae at the junction between the neck and back. The vortex centers were pneumatized, that is, with possibly air-filled chambers.

The paired collarbone in the shoulder region was fused together to form the furcula (forkbone) , as in today's birds . The pelvic bones were not fused together, except for Avimimus . The arms made up 40 to 65 percent of the length of the hind legs. The hand was three-pronged and longest at the second ray. The first finger was strong, while the third finger was thin and often reduced - in Caudipteryx it consisted of only two phalanges. The thighbone (femur) made up 30 percent of the hind leg length , with the shinbone (tibia) being 15 to 20 percent longer than the thighbone. The foot made up 30 to 35 percent of the length of the hind legs.

The metatarsus of Avimimus and the Caenagnathids is designed as an arctometatarsus , which means that the third (middle) metatarsal bone was only about as wide in the lower part as the other two and was strongly tapered in the upper part. However, this feature is absent in the oviraptorids and caudipteryx .

Paleoecology

Undoubted remains of the Oviraptorosauria so far only come from the northern hemisphere from Asia and North America, although there are reports of possible fragmentary oviraptorid remains from the southern hemisphere as well. Representatives of the group have been identified in many different ecosystems. Remains are most often found in the Upper Cretaceous Central Asia in rocks, which indicate a very dry habitat with sand dunes. In North America, fossil remains are rarer and appear sporadically in sediments deposited by rivers in the Upper Cretaceous ( Campanium and Maastrichtian ).

Systematics

literature

Web links

Commons : Oviraptorosauria  - Collection of images, videos and audio files

Individual evidence

  1. ^ Gregory S. Paul : The Princeton Field Guide To Dinosaurs. Princeton University Press, Princeton NJ et al. 2010, ISBN 978-0-691-13720-9 , pp. 144-155, online .
  2. Ji Qiang, Philip J. Currie, Mark A. Norell , Ji Shu-An: Two feathered dinosaurs from northeastern China. In: Nature . Vol. 393, No. 6687, 1998, pp. 753-761, doi : 10.1038 / 31635 .
  3. ^ Rinchen Barsbold, Halszka Osmólska, Mahito Watabe, Philip J. Currie, Khishigjaw Tsogtbaatar: A new oviraptorosaur (Dinosauria, Theropoda) from Mongolia: The first dinosaur with a pygostyle. In: Acta Palaeontologica Polonica. Vol. 45, No. 2, 2000, ISSN  0567-7920 , pp. 97-106.
  4. Tao He, Xiao-Lin Wang, Zhong-He Zhou : A new genus and species of caudipterid dinosaur from the Lower Cretaceous Jiufotang Formation of western Liaoning, China. In: Vertebrata PalAsiatica. Vol. 46, No. 3, 2008, ZDB -ID 2485763-4 , pp. 178-189, digitized version (PDF; 1.82 MB) ( memento of the original from March 3, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and not yet tested. Please check the original and archive link according to the instructions and then remove this notice. . @1@ 2Template: Webachiv / IABot / www.ivpp.cas.cn
  5. ^ A b W. Scott Persons IV, Philip J. Currie, Mark A. Norell: Oviraptorosaur tail forms and functions. In: Acta Palaeontologica Polonica. 2013, S., doi : 10.4202 / app.2012.0093 .
  6. a b c Halszka Osmólska, Philip J. Currie, Rinchen Barsbold: Oviraptorosauria. In: David B. Weishampel, Peter Dodson, Halszka Osmólska (eds.): The Dinosauria . 2nd edition. University of California Press, Berkeley CA 2004, ISBN 0-520-24209-2 , pp. 165-183.
  7. Rui Qiu, Xiaolin Wang, Qiang Wang, Ning Li, Jialiang Zhang and Yiyun Ma. 2019. A New Caudipterid from the Lower Cretaceous of China with Information on the Evolution of the Manus of Oviraptorosauria. Scientific Reports. 9, 6431. DOI: 10.1038 / s41598-019-42547-6
  8. Junchang Lü, Laiping Yi, Hui Zhong, Xuefang Wei: A New Oviraptorosaur (Dinosauria: Oviraptorosauria) from the Late Cretaceous of Southern China and Its Paleoecological Implications. In: PLoS ONE . Vol. 8, No. 11, 2013, e80557, doi : 10.1371 / journal.pone.0080557 .
  9. ^ Matthew C. Lamanna, Hans-Dieter Sues , Emma R. Schachner, Tyler R. Lyson: A New Large-Bodied Oviraptorosaurian Theropod Dinosaur from the Latest Cretaceous of Western North America. In: PLoS ONE. Vol. 9, No. 3, 2014, e92022, doi : 10.1371 / journal.pone.0092022 .
  10. ^ Gregory F. Funston and Philip J. Currie. 2016. A New Caenagnathid (Dinosauria: Oviraptorosauria) from the Horseshoe Canyon Formation of Alberta, Canada, and A Reevaluation of The Relationships of Caenagnathidae. Journal of Vertebrate Paleontology. DOI: 10.1080 / 02724634.2016.1160910
  11. Junchang Lü, Guoqing Li, Martin Kundrát, Yuong-Nam Lee, Zhenyuan Sun, Yoshitsugu Kobayashi, Caizhi Shen, Fangfang Teng and Hanfeng Liu. 2017. High Diversity of the Ganzhou Oviraptorid Fauna Increased by A New “Cassowary-like” Crested Species. Scientific Reports. 7, Article number: 6393. DOI: 10.1038 / s41598-017-05016-6
  12. Sungjin Lee, Yuong-Nam Lee, Anusuya Chinsamy, Junchang Lü, Rinchen Barsbold & Khishigjav Tsogtbaatar. 2019. A New Baby Oviraptorid Dinosaur (Dinosauria: Theropoda) from the Upper Cretaceous Nemegt Formation of Mongolia. PLoS ONE. 14 (2): e0210867. DOI: 10.1371 / journal.pone.0210867
  13. Junchang Lü, Rongjun Chen, Stephen L. Brusatte, Yangxiao Zhu, Caizhi Shen. A Late Cretaceous diversification of Asian oviraptorid dinosaurs: evidence from a new species preserved in an unusual posture. Scientific Reports , 2016; 6: 35780 DOI: 10.1038 / srep35780
  14. Junchang Lü, Philip J. Currie, Li Xu, Xingliao Zhang, Hanyong Pu, Songhai Jia: Chicken-sized oviraptorid dinosaurs from central China and their ontogenetic implications. In: Natural Sciences . Vol. 100, No. 2, 2013, pp. 165-175, doi : 10.1007 / s00114-012-1007-0 .
  15. Junchang Lü, Hanyong Pu, Yoshitsugu Kobayashi, Li Xu, Huali Chang, Yuhua Shang, Di Liu, Yuong-Nam Lee, Martin Kundrát & Caizhi Shen (2015): A New Oviraptorid Dinosaur (Dinosauria: Oviraptorosauria) from the Late Cretaceous of Southern China and Its Paleobiogeographical Implications Scientific Reports 5, 11490, doi: 10.1038 / srep11490