Oviraptoridae
Oviraptorids | |
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Montage of four oviraptorids. Clockwise from top left: Citipati? sp., Nemegtomaia, Huanansaurus and Conchoraptor | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | Saurischia |
Clade: | Theropoda |
Superfamily: | †Caenagnathoidea |
Family: | †Oviraptoridae Barsbold, 1976 |
Type species | |
† Oviraptor philoceratops
, 1924 | |
Subgroups | |
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Oviraptoridae is a group of bird-like, herbivorous and omnivorous maniraptoran dinosaurs. Oviraptorids are characterized by their toothless, parrot-like beaks and, in some cases, elaborate crests. They were generally small, measuring between one and two metres long in most cases, though some possible oviraptorids were enormous. Oviraptorids are currently known only from the Late Cretaceous of Asia, with the most well-known species and complete specimens found only in the Gobi Desert of Mongolia and northwestern China.
Description
The most characteristic feature of this group is the skull structure. Oviraptorids had short snouts and very deep
Classification
The classification of the oviraptorids has been controversial. Most studies divide oviraptorosaurs into two primary sub-groups, the Caenagnathidae and the Oviraptoridae. However, some phylogenetic studies have suggested that many traditional members of the Caenagnathidae may be more closely related to the crested oviraptorids. Because of this, and the fact that at least one study found that Caenagnathus itself may not have been part of the 'caenagnathid' group, Tom Holtz (2010) placed that group close to the Oviraptoridae and termed it the Elmisauridae,[1] though this idea has not gained consensus among other researchers.
The Oviraptoridae itself is traditionally divided into two "subfamilies": the small, short-armed, and mainly crestless subfamily Heyuanniinae and the larger, crested, long-armed Oviraptorinae (
Other possible oviraptorids include
Caenagnathoidea |
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In 2020, during their description of Oksoko, Funston et al. recovered a slightly different cladogram.[3] Because Oviraptor did not clade with Citipati and the other "oviraptorines", they named the latter's clade Citipatiinae, although they did not provide a formal definition. However, according to Mickey Mortimer, the clade can be considered valid because its describers explicitly name it as new, which satisfies ICZN Article 16.1.[4]
Oviraptoridae |
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Paleobiology
Diet
The diet of oviraptorids is not fully understood. Though some appear to have been at least partially carnivorous, they were probably primarily herbivorous or omnivorous.[5]
Originally, oviraptorids were thought to be specialized egg raiders, based on a Mongolian find showing Oviraptor on top of a nest erroneously attributed to the
Their beaks also share similarities with the beaks of herbivorous parrots and tortoises.[7]
Evidence of partial carnivory among some oviraptorines comes from a lizard skeleton preserved in the body cavity of the
Reproduction
Although fossilized
Oviraptorid eggs are shaped like elongated ovals (
The first oviraptorid eggs (of the genus Oviraptor, which mean "Egg thief") were found in close proximity to the remains of the
An oviraptorosaurian specimen from China described in 2005 was found to have two unlaid eggs within the pelvic canal. This suggests that, unlike modern crocodilians, oviraptorosaurs did not produce and lay many eggs at the same time. Rather, the eggs were produced within the reproductive organs in pairs, and laid two at a time, with the mother positioned in the center of the nest and rotating in a circle as each pair was laid. This behavior is supported by the fact that the eggs oval shape, with the more narrow end pointing backward from the birth canal, matching their orientation toward the center of the nest after being laid.[14]
The presence of two shelled eggs within the birth canal shows that oviraptorosaurs were intermediate between the reproductive biology of crocodilians and modern birds. Like crocodilians, they had two oviducts. However, crocodilians produce multiple shelled eggs per oviduct at a time, whereas oviraptorosaurs, like birds, produced only one egg per oviduct at a time.[14]
In 2017, paleontologists discovered colored pigments in some fossilized oviraptorid embryos of the egg-shell genus
Metabolism
A study by Robert Eagle et al. of the University of California-Los Angeles indicates that from specimens of eggs found in Mongolia and examination of the isotopes carbon-13 and oxygen 18 found within, Oviraptorids had body temperatures that could be elevated higher than that of the surrounding environment but lower than that of birds. This is very different from the isotope ratios of sauropod dinosaurs like Brachiosaurus, which had body temperatures of up to 100 °F (38 °C) and were fully endothermic.[16]
Feathers
Oviraptorids were probably feathered, since some close relatives were found with feathers preserved (including species of Caudipteryx, Protarchaeopteryx and Similicaudipteryx).[17][18] Another finding pointing to this is the discovery in Nomingia of a pygostyle, a bone that results from the fusion of the last tail vertebrae and is responsible in birds to hold a fan of feathers in the tail.[19] Finally, the arm position of the brooding Citipati would have been far more effective if feathers were present to cover the eggs.[20]
Pathology
The brooding oviraptorid specimen
Paleoenvironment
Almost all oviraptorids come from
See also
References
- ^ Holtz, Thomas R. Jr. (2011) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages, Winter 2011 Appendix.
- ^ PMID 24647078.
- PMID 33204472.
- ^ "Oviraptorosauria".
- ^ .
- ^ S2CID 22333224.)
{{cite journal}}
: CS1 maint: multiple names: authors list (link - hdl:10852/11785.
- ^ S2CID 4245228.
- ^ Bever, G.S. and Norell, M.A. (2009). "The perinate skull of Byronosaurus (Troodontidae) with observations on the cranial ontogeny of paravian theropods." American Museum Novitates, 3657: 51 pp.
- ^ a b c d Clark, J.M., Norell, M.A., & Chiappe, L.M. (1999). "An oviraptorid skeleton from the Late Cretaceous of Ukhaa Tolgod, Mongolia, preserved in an avianlike brooding position over an oviraptorid nest." American Museum Novitates, 3265: 36 pp., 15 figs.; (American Museum of Natural History) New York. (5.4.1999).
- PMID 22347465.
- ^ Varricchio, D.J. (2000). "Reproduction and Parenting," in Paul, G.S. (ed.). The Scientific American Book of Dinosaurs. New York: St. Martin's Press, pp. 279–293.
- ^ Osborn, H.F. (1924). "Three new Theropoda, Protoceratops zone, central Mongolia." American Museum Novitates, 144: 12 pp., 8 figs.; (American Museum of Natural History) New York. (11.7.1924).
- ^ S2CID 19470371.
- PMID 28875070.
- ^ "Sun-warmed dinosaurs may have been surprisingly good sprinters: Some had the ability to warm themselves by drawing heat from the sun".
- S2CID 205001388. Archived from the original(PDF) on 2008-12-17.
- ^ Ji, Q., and Ji, S. (1997). "A Chinese archaeopterygian, Protarchaeopteryx gen. nov." Geological Science and Technology (Di Zhi Ke Ji), 238: 38–41. Translated By Will Downs Bilby Research Center Northern Arizona University January, 2001
- ^ Barsbold, R.; Osmólska, H.; Watabe, M.; Currie, P.J.; Tsogtbaatar, K. (2000). "New Oviraptorosaur (Dinosauria, Theropoda) From Mongolia: The First Dinosaur With A Pygostyle". Acta Palaeontologica Polonica. 45 (2): 97–106.
- ^ Paul, G.S. (2002). Dinosaurs of the Air: The Evolution and Loss of Flight in Dinosaurs and Birds. Baltimore: Johns Hopkins University Press.
- ^ Molnar, R. E., 2001, Theropod paleopathology: a literature survey: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, p. 337-363.