This timeline of oviraptorosaur research is a chronological listing of events in the history of paleontology focused on the oviraptorosaurs, a group of beaked, bird-like theropod dinosaurs. The early history of oviraptorosaur paleontology is characterized by taxonomic confusion due to the unusual characteristics of these dinosaurs. When initially described in 1924 Oviraptor itself was thought to be a member of the Ornithomimidae, popularly known as the "ostrich" dinosaurs, because both taxa share toothless beaks.[1] Early caenagnathid oviraptorosaur discoveries like Caenagnathus itself were also incorrectly classified at the time, having been misidentified as birds.[1]
Drawing of the left arm and both hands of the Oviraptor type specimen AMNH 6517
1920s
1923
A specimen of the species that would come to be named Oviraptor philoceratops was found preserved on top of a nest of eggs.[2]
1924
Osborn described the new genus and species Oviraptor philoceratops.[3] He classified it as an ornithomimid because it didn't have any teeth in its jaws[1] and interpreted the genus as being adapted to a diet of eggs.[2] Since a specimen was found preserved on top of a nest of eggs presumed to belong to Protoceratops, Osborn thought that it was smothered by a sandstorm while in the act of raiding the nest.[2]
Drawing of the skull of Oviraptor, type specimen AMNH 6517
1940
R. M. Sternberg described the new genus and species Caenagnathus collinsi and named the Caenagnathidae and Caenagnathoidea.[3] He thought they were birds.[1]
1950s
1956
Romer followed Osborn's original classification of Oviraptor as an ornithomimid. He also observed that caenagnathids had reptilian characteristics and may have been coelurosaurs.[1]
1960s
1960
Wetmore questioned the hypothesis that caenagnathids were birds because their remains exhibit some reptilian traits.[1]
1966
Romer continued to follow Osborn's original classification of Oviraptor as an ornithomimid.[1]
Ostrom described the new genus and species Microvenator celer.[4]
Steel followed Osborn's original classification of Oviraptor as an ornithomimid.[1] He also questioned the avian status of caenagnathids and proposed that they might actually be coelurosaurs instead.[1]
Artist's restoration of Microvenator
1971
Cracroft named the new species Caenagnathus sternbergi.[3] He thought it was a bird.[1]
1972
Russell argued against the classification of Oviraptor as an ornithomimid.[1]
1976
Osmolska recognized that caenagnathids were theropods and classified Oviraptor as a member of the family.[1]
Barsbold classified Oviraptor as a member of the new taxa Oviraptorinae and Oviraptoridae.[1]
Kurzanov described the new genus and species Avimimus portentosus.[3]
Known skeletal material of Ajancingenia, formerly "Ingenia"
Barsbold described the new genus and species Ingenia yanshini.[4] He also named the subfamily Ingeniinae[4] and classified the family Caenagnathidae in the Oviraptorosauria.[1]
Osmolska described the new genus and species Elmisaurus rarus.[4]
1983
Barsbold proposed that oviraptorosaurs used their powerful beaks to feed on shelled mollusks.[2]
1986
Barsbold described the new species Oviraptor mongoliensis.[3]
Barsbold described the new genus and species Conchoraptor gracilis.[4]
Gauthier considered oviraptorosaurs, deinonychosaurs, and avialans to be maniraptorans.[1]
1988
Currie and Russell observed that caenagnathids had arctometatarsalian feet.[2]
1990s
Fossilized Oviraptor nest, specimen AMNH FR 6508
1991
Jerzykiewicz and Russell observed that oviraptorosaurs seem to have been most common during the Djadokhta stage.[2]
Currie and others built a case for interpreting oviraptorosaurs as egg-eaters who supplemented their diet with small prey. They noted supporting traits like the animals' ability to give a "powerful nipping bite" with the front of its beak. Oviraptorosaurs also had tooth-like projections from the roof of the mouth, which resemble similar adaptations in modern egg-eating mammals.Nesting Citipati specimen nicknamed "Big Auntie" The orientation of the throat on the underside of the jaw is also consistent with this reconstruction of oviraptorosaur paleoecology.[2]
Russell and Dong argued that the Maniraptora (which includes Oviraptorosauria) was a polyphyletic assemblage of unrelated groups. Instead they classified the traditional oviraptorosaurs with the ornithomimids, therizinosauroids, and troodontids in a new, greatly expanded Oviraptorosauria.[5]
1994
Norell and others reported the discovery of a tiny theropod skeleton in an oviraptorid nest. They suggested this find was evidence that oviraptorosaur hunted tiny game. They also noted that the supposed Protoceratops eggs of the Central Asiatic Expeditions actually preserved the embryonic remains of oviraptorosaurs.[2]
1996
Currie reported the presence of nests of large eggs more than 40 centimetres (16 in) long in China. Oviraptorosaurs would come to be considered possible candidates for the egg layers.[2]Fossilized Citipati egg with preserved embryo
Dong and Currie reported the discovery of an oviraptorid from the Djadokhta Formation of northern China preserved on top of a nest of eggs. This overturned more than 60 years of interpreting the Oviraptor of the Central Asiatic Expeditions as a rapacious egg-thief in favor of it likely being a faithful mother at her nest. The researchers reconstructed the way mother oviraptorosaurs built their nests. The standing mother would lay a pair of eggs and bury them by hand. Then she would turn and repeat the process until she had made a ring of egg-pairs completely around herself. Since by then the area where she was standing would be higher than the eggs, she would repeat the process with another ring of egg-pairs as a second layer. This process would gradually build an egg mound containing as many as 30 eggs in up to three layers.[2]
1997
Sues published a critical review of earlier interpretations of the oviraptorosaurs' evolutionary relationships and formulated the clade's first synapomorphy-based diagnosis. He also performed a cladistic analysis and found oviraptorosaurs to be the sister group of the therizinosaurs.[6]
Sereno regarded oviraptorosaurs as maniraptorans and found them to be the sister group of Paraves (which includes deinonychosaurs and birds) in a cladistic analysis.[6]
Padian and others published a cladistic definition for Oviraptorsauris for the first time; all taxa closer to Oviraptor than to birds.[6]
Cast of a Caudipteryx zoui specimen, Houston Museum of Natural Science
Barsbold described the new genus Rinchenia for the species Oviraptor mongoliensis.[3] Barsbold credited Currie and Padian for defining Oviraptorosauria as the Oviraptoridae and all taxa closer to Oviraptor.[6]
1998
Sereno regarded oviraptorosaurs as maniraptorans and found them to be the sister group of Paraves (which includes deinonychosaurs and birds) in a cladistic analysis.[6] He defined oviraptorosaurs as all maniraptorans closer to Oviraptor than to Neornithes.[6]
Currie, Norell, and Ji described the new genus and species Caudipteryx zoui.[3]
Ji and others reported the presence of gastroliths in Caudipteryx. These are evidence for an herbivorous diet.[2]
Makovicky and Sues considered oviraptorosaurs to be the sister group of the therizinosaurs.[6]
1999
Sereno found Caudipteryx to be a basal oviraptorosaur. He also erected the clade Caenagnathoidea for the caenagnathids and oviraptorids.[6]
Elzanowski performed a cladistic analysis and found a group consisting of oviraptorosaurs, ornithomimosaurs and therizinosaurs were more closely related to birds than deinonychosaurs. No other cladistic study in the history of dinosaur research had come up with this result.[6]
Padian and others changed the definition of Oviraptorosauria from a stem-based clade to a node-based one. They defined the oviraptorosaurs as "Oviraptor and Chirostenotes (=Caenagnathus) and all the descendants of their most recent common ancestor."[6]
Clark and others observed that oviraptorosaurs are among the most common dinosaurs found at Ukhaa Tolgod in Mongolia.[2] They reported further specimens preserved on nests in brooding position. They suggested contrary to Dong and Currie's 1996 reconstruction of oviraptorosaur nest-building behavior that the animals may have constructed their nests by maneuvering the eggs into position by hand. However, this explanation is less parsimonious and has less evidentiary support, so it never gained favor among paleontologists.[2]
Citipati osmolskae and an unnamed Citipati species
Clark, Norell, and Barsbold described the new genus and species Citipati osmolskae.[4]
Clark, Norell, and Barsbold described the new genus and species Khaan mckennai.[4]
David J. Varrichio reported the first occurrences of oviraptorosaurs from Montana.[7] The first find was an articular region from the lower jaw of Caenagnathus sternbergi of Campanian age from the Two Medicine Formation.[7] This species had previously only been known from the Canadian province of Alberta.[7] Another new Montanan oviraptorosaur specimen, a foot found in the Hell Creek Formation, was assigned to Leptorhynchus elegans (as Elmisaurus elegans).[7]
Kevin Padian, Ji Qiang and Ji Shu-an published a review of known feathered dinosaurs and their implications for the origin of flight.[8] The authors observe that many aspects of the distribution of feather homologues meet the expectations of earlier phylogenetic hypotheses, including a gradual transition from primitive filaments in Sinosauropteryx to the shared filaments and "rudimentary" true feathers in Caudipteryx and Protarchaeopteryx, to flight feathers in Archaeopteryx.[9] The team speculates that the plumulaceous feathers in Cauditeryx and Protarchaeopteryx may have originated as tufts of Sinosauropteryx-style filaments, the shafts of which possibly formed by the consolidation of individual filaments.[10] The parallel nature of the barbs in Caudipteryx and Protarcheopteryx suggest the existence of barbules.[11] This suggests that barbules, which are necessary for flight-worthy wings, evolved prior to flight.[11]
Cladogram of feathered dinosaurs from Padian et al. 2001
Taxa marked with a P were known to bear plumulaceous or pennaceous feathers at the time of the study. Taxa marked with F were known to bear simple filamentous integumentary structures.
2002? Teresa Maryańska and others confirmed Sereno's finding that Caudipteryx was an oviraptorosaur. They also found Avimimus to be an oviraptorosaur as well.[6]
2002
Xu and others described the new genus and species Incisivosaurus gauthieri.[3] Their research supported recent findings that Caudipteryx and Avimimus were oviraptorosaurs.[6]
Maryanska and others performed a cladistic analysis that found oviraptorosaurs to be avialans.[6]
Zelenitsky and others studied the shape and shell histology of the large fossil eggs reported from China by Currie in 1996 and concluded that they may have been laid by oviraptorosaurs. Given their large size, this implied that giant oviraptorosaurs remained to be discovered.[2]
2003
Lü described the new genus and species Heyuannia huangi.[4]
Easter, J. (2013). "A new name for the oviraptorid dinosaur "Ingenia" yanshini (Barsbold, 1981; preoccupied by Gerlach, 1957)". Zootaxa3737 (2): 184–190. doi:10.11646/zootaxa.3737.2.6. PMID25112747.
Ji Qiang; Lü Jun-Chang; Wei Xue-Fang; Wang Xu-Ri (2012). "A new oviraptorosaur from the Yixian Formation of Jianchang, Western Liaoning Province, China". Geological Bulletin of China31 (12): 2102–2107.
Nicholas R. Longrich; Philip J. Currie; Dong Zhi-Ming (2010). "A new oviraptorid (Dinosauria: Theropoda) from the Upper Cretaceous of Bayan Mandahu, Inner Mongolia". Palaeontology53 (5): 945–960. doi:10.1111/j.1475-4983.2010.00968.x. Bibcode: 2010Palgy..53..945L.
Longrich, N. R.; Barnes, K.; Clark, S.; Millar, L. (2013). "Caenagnathidae from the Upper Campanian Aguja Formation of West Texas, and a Revision of the Caenagnathinae". Bulletin of the Peabody Museum of Natural History54: 23–49. doi:10.3374/014.054.0102.
Lü, J.; Currie, P. J.; Xu, L.; Zhang, X.; Pu, H.; Jia, S. (2013). "Chicken-sized oviraptorid dinosaurs from central China and their ontogenetic implications". Naturwissenschaften100 (2): 165–175. doi:10.1007/s00114-012-1007-0. PMID23314810. Bibcode: 2013NW....100..165L.
Lü, J.; Tomida, Y.; Azuma, Y.; Dong, Z.; Lee, Y.-N. (2004). "New oviraptorid dinosaur (Dinosauria: Oviraptorosauria) from the Nemegt Formation of southwestern Mongolia". Bulletin of the National Science Museum, Tokyo, Series C30: 95–130.
Lu, J.; Zhang, B.-K. (2005). "A new oviraptorid (Theropoda: Oviraptorosauria) from the Upper Cretaceous of the Nanxiong Basin, Guangdong Province of southern China". Acta Palaeontologica Sinica44 (3): 412–422.
Varrichio, D. J. (2001). "Late Cretaceous oviraptorosaur (Theropoda) dinosaurs from Montana". in Tanke, D. H.; Carpenter, K. (in en). Mesozoic Vertebrate Life. Life of the Past. Indiana University Press. pp. 42–57.
Wang, S.; Sun, C.; Sullivan, C.; Xu, X. (2013). "A new oviraptorid (Dinosauria: Theropoda) from the Upper Cretaceous of southern China". Zootaxa3640 (2): 242–257. doi:10.11646/zootaxa.3640.2.7. PMID26000415.
Wei Xuefang, Pu Hanyong, Xu Li, Liu Di and Lü Junchang (2013). "A New Oviraptorid Dinosaur (Theropoda: Oviraptorosauria) from the Late Cretaceous of Jiangxi Province, Southern China". Acta Geologica Sinica (English Edition)87 (4): 899–904. doi:10.1111/1755-6724.12098.
Xu, X.; Han, F.-L. (2010). "A new oviraptorid dinosaur (Theropoda: Oviraptorosauria) from the Upper Cretaceous of China". Vertebrata PalAsiatica48 (1): 11–18.
Zanno, Lindsay E.; Sampson, Scott D. (2005). "A new oviraptorosaur (Theropoda; Maniraptora) from the Late Cretaceous (Campanian) of Utah". Journal of Vertebrate Paleontology25 (4): 897–904. doi:10.1671/0272-4634(2005)025[0897:ANOTMF2.0.CO;2].
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