OVIRAPTOROSAURIA, BARSBOLD, 1976

Pittman, Michael & Xu, Xing, 2020, Pennaraptoran Theropod Dinosaurs Past Progress And New Frontiers, Bulletin of the American Museum of Natural History 2020 (440), pp. 1-353 : 38-43

OVIRAPTOROSAURIA

Oviraptorosaurian fossils were first discovered in the 1920s and are now represented by more than 40 genera spanning a size range across three orders of magnitude (table 1). The 1920s to 1940s, the 1970s, 1980s, 1990s, and the past 20 years have been key periods in our documentation of the oviraptorosaurian fossil record, which is limited to Laurasian continents and dominated by discoveries from Asia and North America (fig. 1). The last 30 years have seen the discovery of most known oviraptorosaurian taxa, particularly from the Cretaceous of China and the Late Cretaceous of North America and Mongolia. These discoveries have greatly broadened our understanding of this group, including in regard to the evolution of their beaked and strangely pneumatized skulls, as well as the origin of brooding in theropod dinosaurs.

ASIA: This continent is the home of the first described oviraptorosaurian species (Osborn, 1924), the eponymous species Oviraptor . Asia is also home to more than 75% of valid oviraptorosaurian genera. The most important sources of Asian oviraptorosaurians are the Early Cretaceous (Hauterivian-Aptian) Jehol Lagerstätte of northeastern China, the Campanian-Maastrichtian Ganzhou oviraptorid fauna of southern

TABLE 1 Oviraptorosaurian fossil record Geological Country Period Age Age Reference Taxa Reference Unit Jehol Group Incisivosaurus , Caudipteryx, Ji and Ji, 1997 ; Ji et al., 1998; 2012; (Yixian Ningyuansaurus , Protarchaeop- Early Barremian- Chang et al., 2009, 2017; Zhou et al., 2000; Xu et al., 2002 a, Formation; China teryx, Similicaudipteryx (possibly Cretaceous Aptian Pan et al., 2013 2010a; He et al., 2008; Balanoff et Jiufotang Incisivosaurus ), Xingtianosaurus ; al., 2009; Qiu et al., 2019 Formation) Similicaudipteryx Bureau of Geology and Banji , Corythoraptor, Xu and Han, 2010 ; Lü et al., 2013a; Nanxiong Late Campanian- Mineral Ganzhousaurus , Huanansaurus , China Wang et al., 2013a; Wei et al., Formation Cretaceous Maastrichtian Resources of Jiangxi Jiangxisaurus , Nankangia , 2013; Lü et al., 2015, 2016, 2017 Province, 1984 Tongtianlong Haoling Early China Aptian/Albian Xu et al., 2012a Luoyanggia Lü et al., 2009 Formation Cretaceous Bureau of Geology and Dalangshan Late Mineral Resources of China Maastrichtian Heyuannia Lü, 2003 Formation Cretaceous Guangdong Province, 1988 Pingling Late China Maastrichtian Zhao et al., 1991 Shixinggia Lü and Zhang, 2005 Formation Cretaceous Qiupa Late Campanian- China Jiang et al., 2011 Yulong Lü et al., 2013b Formation Cretaceous Maastrichtian Gaogou Late Cenomanian- China Liang et al., 2009 Beibeilong Pu et al., 2017 Formation Cretaceous Turonian Erlian van Itterbeeck et al. , Late Campanian- Avimimus , Caenagnathasia, Kurzanov, 1981 ; Xu et al., 2007; (Iren Dabasu) China 2005; Bonnetti et al., Cretaceous Maastrichtian Gigantoraptor Yao et al., 2015 ; Ma et al., 2017 Formation 2014 Wulansuhai (Bayan Late Longrich et al., 2010; Xu et al., China Campanian Godefroit et al., 2008 Machairasaurus , Wulatelong Mandahu ) Cretaceous 2013b Formation Wangshi Late China Campanian An et al., 2016 Anomalipes Yu et al., 2018 Group Cretaceous van Itterbeeck et al., Osborn, 1924; Kurzanov, 1981; Djadokhta Late 2005; Dingus et al., Avimimus , Citipati , Khaan , Mongolia Campanian Clark et al., 2001; Clark et al., Formation Cretaceous 2008; Hasegawa et al., Oviraptor 2002; Balanoff and Norell, 2012 2009

1 continued

China (Nanxiong Formation) as well as the southern Mongolian Campanian Djadokhta Formation (and the similar Wulansuhai (Bayan Mandahu) Formation in China), Campanian-Maastrichtian Barun Goyot Formation, and the Maastrichtian Nemegt Formation.

Jehol oviraptorosaurians represent the oldest unequivocal oviraptorosaurian records, and the six described taxa include some articulated specimens preserving feathers, gastroliths, and stomach contents. The early-diverging oviraptorosaurians Incisivosaurus , Protarchaeopteryx , Similicaudipteryx , Caudipteryx , Xingtianosaurus , and Ningyuansaurus are the only known toothed forms and have less specialized skulls compared to later oviraptorosaurians ( Ji et al., 1998; Zhou et al., 2000; Xu et al., 2002 a; Balanoff et al., 2009; Qiu et al., 2019). Caudipteryx is known for its pennaceous feathered arms, gastroliths, and a tail plume probably used for display purposes ( Ji et al., 1998; Zhou et al., 2000; Pittman et al., 2013; Persons et al., 2014). It is known from two species ( Ji et al., 1998; Zhou et al., 2000), although this is contested. Both specimens were recovered from the ~125 Ma Yixian Formation in Liaoning province, with both 2-D and 3-D preservations. Two specimens of Similicaudipteryx , another Yixian Formation genus, show radical changes to feather morphology during ontogeny (Xu et al., 2010a). However, these two specimens might be specimens of Incisivosaurus (Xu, 2020) . Ningyuansaurus possibly preserves seeds within its body cavity ( Ji et al., 2012). Xingtianosaurus is the most recently named Jehol genus, which is known from an articulated postcranial skeleton (Qiu et al., 2019). Luoyanggia is an Aptian- to Albian-aged oviraptorid from the Haoling Formation of Henan, central China, which was previously thought to be Late Cretaceous in age (Lü et al., 2009; Xu et al., 2012a).

The Late Cretaceous Ganzhou fauna of Jiangxi, southern China, has the greatest known diversity of oviraptorid oviraptorosaurians with seven reported genera in the Campanian-Maastrichtian Nanxiong Formation: Banji , Huanansaurus , Jiangxisaurus , Tongtianlong , Ganzhousaurus , Nankangia , and Corythoraptor (Xu and Han, 2010; Lü et al., 2013a, 2015, 2016, 2017; Wang et al., 2013a; Wei et al., 2013). Embryos of an oviraptorid have also been recovered from this formation (Wang et al., 2016a). Heyuannia is an oviraptorid genus described from a partial skeleton from the Maastrichtian Dalangshan Formation of Guangdong, southern China (Lü, 2003). “ Ingenia ,” or Ajancingenia yanshini , from the Campanian-Maastrichtian Barun Goyot Formation of southern Mongolia (Barsbold, 1981; Easter, 2013) has been referred to this genus as a second species, H. yanshini , but this involves a very large geographical and temporal separation between species (Funston et al., 2017). Shixinggia is another described Guangdong oviraptorid from the Maastrichtian Pingling Formation (Lü and Zhang, 2005). Yulong is a chicken-sized oviraptorid represented by excellent fossil material from the Upper Cretaceous Qiupa Formation of Henan, central China (Lü et al., 2013b), while Beibeilong is a caenagnathid known from a perinate skeleton and some eggs from the Cenomanian-Turonian Gaogou Formation of the same province (Pu et al., 2017). Anomalipes is a recently reported caenagnathid from the Campanian Wangshi Group of Shandong Province, known only from hind-limb elements (Yu et al., 2018). The largest known oviraptorosaurian—the caenagnathid Gigantoraptor —was recovered in the northernmost frontier of China from the Campanian-Maastrichtian Erlian (Iren Dabasu) Formation of Nei Mongol (Inner Mongolia) ( Xu et al., 2007). This is also the locality for one of the smallest oviraptorosaurians, Avimimus , which was first reported from similarly aged rocks in Mongolia (Kurzanov, 1981), although these assignments would benefit from review, as they may represent different taxa. The Campanian Wulansuhai (Bayan Mandahu) Formation, also in the Gobi Desert region, is the home to the oviraptorids Machairasaurus and Wulatelong and some other indeterminate oviraptorid material (Longrich et al., 2010; Xu et al., 2013b).

Mongolian oviraptorosaurians are dominated by oviraptorids, with three genera from the Campanian Djadokhta Formation ( Oviraptor , Citipati , and Khaan ) (Osborn, 1924; Clark et al., 2001, 2002; Balanoff and Norell, 2012), four genera from the Maastrichtian Nemegt Formation ( Gobiraptor , Nomingia , Rinchenia , and Nemegtomaia ) (Barsbold, 1986; Barsbold et al., 2000; Lü et al., 2004, 2005; Fanti et al., 2012; Funston et al., 2017; Lee et al., 2019) and three from the Campanian-Maastrichtian Barun Goyot Formation (“ Ingenia ”/ Ajancingenia / Heyuannia yanshini , Conchoraptor , and Nemegtomaia [also from the Nemegt]; see Fanti et al., 2012, for details of Maastrichtian portion) (Barsbold, 1981; 1986; Longrich et al., 2010; Funston et al., 2017). Several skeletons are known for Khaan and Citipati from the rich fossil beds of Ukhaa Tolgod, including brooding specimens, single species group associations and embryos (Norell et al., 1995, 2001; Clark et al., 2001).

Avimimus is a small, early-diverging oviraptorosaurian closer to Caenagnathidae and Oviraptoridae that is known from multiple formations in Mongolia, including the Djadokhta, Nemegt, and Barun Goyot (Kurzanov, 1981; Longrich et al., 2010). Elmisaurus is a caenagnathid from the Nemegt Formation (Osmólska, 1981; Currie et al., 2016). The holotype of the caenagnathid Caenagnathasia is a pair of dentaries from a single individual recovered from the Turonian Bissekty Formation of Uzbekistan ( Currie et al., 1993). A partial dentary referred to Caenagnathasia is known from the Erlian (Iren Dabasu) Formation of Nei Mongol, China ( Yao et al., 2015). Few caenagnathid skull elements have been reported in Asia; these are from the perinate Beibeilong and the mandible of Gigantoraptor and a similarly sized specimen from the Gobi Desert ( Xu et al., 2007; Tsuihiji et al., 2015; Ma et al., 2017; Pu et al., 2017).

NORTH AMERICA: The early-diverging caenagnathid Microvenator was recovered from the Aptian-Albian Cloverly Formation and is a historically important specimen and likely that of a juvenile. It is the continent’s oldest oviraptorosaurian (Makovicky and Sues, 1998). Late Cretaceous caenagnathids dominate the North American oviraptorosaurian fossil record. Chirostenotes , currently known from the species C. pergracilis , was the first discovered caenagnathid as well as the first described North American oviraptorosaur (Gilmore, 1924). The Campanian Dinosaur Park Formation of Canada is the most important source of North American caenagnathids including Chirostenotes (also referred to possible material in the Campanian Two Medicine and Maastrichtian Hell Creek formations of the northern United States [ Osmólska et al., 2004]), Leptorhynchos ( Longrich et al., 2013) (also the Campanian-Maastrichtian Aguja Formation of the southern United States) as well as Caenagnathus , the caenagnathid that lends its name to the clade ( Currie et al., 1993). Hagryphus is a caenagnathid from the Campanian Kaiparowits Formation of Utah, known from forelimb material (Zanno and Sampson, 2005). Moving into the latest Cretaceous, Epichirostenotes and Apatoraptor are caenagnathids from the Campanian-Maastrichtian Horseshoe Canyon Formation of Canada. Both have preserved skull elements, and the holotype of Apatoraptor is a largely articulated partial skeleton. Ojoraptorsaurus is a caenagnathid known from pubic bones recovered from the Maastrichtian Ojo Alamo Formation of the southwestern United States (Sullivan et al., 2011; Funston and Currie, 2016). Anzu is the largest described caenagnathid from North America and is one of the best-preserved North American oviraptorosaurians ( Lamanna et al., 2014). It is known from the Maastrichtian Hell Creek Formation of North and South Dakota ( Lamanna et al., 2014). Fossil eggshell material and undescribed skeletal material from the top of the Cedar Mountain Formation (Cenomanian-Turonian) of Utah represents an even larger taxon that was similarly sized to Gigantoraptor (Makovicky et al., 2015; Tucker et al., 2020).

EUROPE: Oviraptorosaurians are poorly known from Europe with representation from only isolated postcranial material (Naish et al., 2001; Csiki and Grigorescu, 2005) whose referrals have been subsequently challenged (Csiki et al., 2010; Allain et al., 2014).

Isolated elements from Cretaceous strata of Gondwana have been interpreted as deriving from oviraptorosaurians, but these records have not withstood subsequent reevaluation. An isolated cervical from the Maastrichtian El Brete Formation of Argentina was described as an oviraptorosaurian (Frankfurt and Chiappe, 1999), but has since been reinterpreted as a noasaurid theropod (Agnolín and Martinelli, 2007). Elements from the Lower Cretaceous Otway Group of Australia described as an oviraptorosaurian lower jaw fragment and dorsal vertebra (Currie et al., 1996), have since been attributed to Unenlagiinae or other theropod clades (Agnolín et al., 2010). To date, no unambiguous records of oviraptorosaurians from Gondwanan continents exist.