Oviraptoridae
Encyclopedia
Oviraptoridae is a group of bird-like, herbivorous and omnivorous maniraptora
n dinosaur
s. 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 gigantic. The most well-known species and complete specimens all are found only in the Gobi Desert
of Mongolia
and northwestern China
, though one possible sub-group, the elmisaurines, as well as the possible primitive species Microvenator celer lived in what is now North America. Definitive oviraptorids first appeared in the Cenomanian
stage of the late Cretaceous
Period (84 million years ago), although the possible oviraptorid Microvenator is known from the Aptian
stage of the Early Cretaceous
Period. The last known members became extinct at the end of the Maastrichtian
stage, 65.5 million years ago.
s. Some taxa (Oviraptor, Citipati, Rinchenia) had a midline crest on top of the skull, resembling that of a cassowary
. Other distinguishing characters include a bony spike intruding on the mandibular fenestra, nostrils placed very high and far back on the snout, an extremely thin bony bar beneath the eye, and highly pneumatized skull bones. Like their relatives the caenagnathids, the jaws were edentulous (with no teeth), having instead two small bony projections on the top jaw.
The classification of the oviraptorids has been controversial. Most early studies divided oviraptorosaurs into two primary sub-groups, the Caenagnathidae and the Oviraptoridae. The Oviraptoridae was further divided into the small, short-armed, and crestless subfamily "Ingeniinae" (the name was preoccupied by an invertebrate group), and the larger, crested, long-armed Oviraptorinae. However, later phylogenetic studies showed that many traditional members of the Caenagnathidae were in fact more closely related to the crested oviraptorids. Because Caenagnathus
itself is no longer considered part of this group, the subfamily is usually now termed the Elmisaurinae. The taxonomy below follows the one presented by Thomas Holtz, Jr. in 2010.
Other possible oviraptorids include Nomingia gobienisis
, Shixinggia oblita
, and the early Microvenator celer
. All three have been suggested to be oviraptorines, elmisaurines, or more primitive than either group.
deposits of the Gobi Desert
. Even in the late Cretaceous period, much of this area was desert, or at least very dry, habitat. In many of the localities where they are found, oviraptorids are among the most abundant dinosaurs present, second only to ankylosaurs and protoceratopsid
s. This is consistent with the idea that they were primarily herbivores, which tend to far outnumber carnivores in a given environment. Oviraptorids appear to have been far more abundant in arid habitats dominated mainly by small dinosaurs (such as those preserved in the Barun Goyot
and Djadochta Formation
s) than in wetter ecosystems where large dinosaurs are common (such as the Nemegt Formation
). The same pattern holds true for protoceratopsids, indicating that both groups preferred dry, desert-like habitat, and fed mainly on the types of tough, low-growing plant life that grows in arid climates.
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 ceratopsia
n dinosaur Protoceratops
. However, discoveries in the 1990s, including Citipati specimens clearly brooding (rather than predating) the same types of nests, and a Citipati embryo
inside the same type of egg preserved in these nests, showed that the "specialized egg thief" idea was incorrect. Still, some scientists have suggested that oviraptorids may have fed on shelled food items like eggs or shellfish. However, animals specialized for eating shelled food typically have broad, crushing beaks or teeth. In contrast, the jaws of oviraptorids had thin, sharp edges probably supporting shearing beaks, ill suited for cracking shells. Among other known animals, the beaks of oviraptorids most closely resemble those of herbivorous dicynodont
synapsid
s, which are usually considered herbivorous. Their beaks also share similarities with the beaks of herbivorous parrot
s and tortoise
s.
Evidence of partial carnivory among some oviraptorines comes from a lizard skeleton preserved in the body cavity of the type specimen of Oviraptor and two hatchling Byronosaurus
skulls found in a Citipati nest. Some scientists have also suggested that some oviraptorids (especially the small-handed, weak-clawed "ingeniines") fed mainly on plant material.
Although fossilized dinosaur eggs are generally rare, oviraptorid eggs are relatively well known. Several oviraptorid nests, eggs, and embryos are known, mostly uncovered in the Gobi Desert
. Some specimens of the Oviraptor philoceratops
and Citipati osmolskae
have been found in brooding
positions. described in 1999, All of the nesting specimens are situated on top of egg clutches, with their limbs spread symmetrically on each side of the nest, front limbs covering the nest perimeter. This brooding posture is found today only in birds and supports a behavioral link between birds and theropod dinosaurs.
Oviraptorid eggs are shaped like elongated ovals (elongatoolithid) and resemble the eggs of ratite
birds (such as ostrich
es) in texture and shell structure. In the nest, eggs are typically found in pairs and arranged in concentric circles of up to three layers, with complete clutches consisting of as many of 22 eggs in some species. The eggs of Citipati are the largest known definitive oviraptorid eggs, at 18 cm. In contrast, eggs associated with Oviraptor are only up to 14 cm long.
Ironically, it was the association with eggs that gave oviraptorids their name (which means 'egg thieves'). The first oviraptorid eggs (of the genus Oviraptor) were found in close proximity to the remains of the ceratopsian dinosaur Protoceratops
and it was assumed that the oviraptorids were preying upon the eggs of the ceratopsians. It was not until 1993, when a Citipati embryo was discovered inside an egg of the type assigned to Protoceratops, that the error was corrected. Norell et al., who recognized the embryo as oviraptorid, assigned it to the genus Citipati. The egg containing the embryo was smaller than most known Citipati eggs at only 12 cm, though it was partially eroded and broken into three pieces, making an accurate estimate of its original size difficult. The embryo-bearing egg was otherwise identical to other oviraptorid eggs in shell structure and was found in an isolated nest, again arranged in a circular pattern.
An oviraptorosaurian specimen from China
described in 2005 was found to have two unlaid eggs within the pelvic canal. This suggests that, unlike modern crocodilia
ns, 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.
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 oviduct
s. However, crocodilians produce multiple shelled eggs per oviduct at a time, whereas oviraptorosaurs, like birds, produced only one egg per oviduct at a time.
ed, since some close relatives were found with feathers preserved (Caudipteryx
and possibly Protarchaeopteryx
). 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. Finally, the arm position of the brooding Citipati would have been far more effective if feathers were present to cover the eggs.
and possible longitudinal
groove leftover from a healed fracture of the right ulna
. Other oviraptorids have had pathological features reported in their phalanges but these have not been described in detail in the scientific literature.
Maniraptora
Maniraptora is a clade of coelurosaurian dinosaurs which includes the birds and the dinosaurs that were more closely related to them than to Ornithomimus velox. It contains the major subgroups Avialae, Deinonychosauria, Oviraptorosauria and Therizinosauria. Ornitholestes and the Alvarezsauroidea...
n dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
s. 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 gigantic. The most well-known species and complete specimens all are found only in the Gobi Desert
Gobi Desert
The Gobi is a large desert region in Asia. It covers parts of northern and northwestern China, and of southern Mongolia. The desert basins of the Gobi are bounded by the Altai Mountains and the grasslands and steppes of Mongolia on the north, by the Hexi Corridor and Tibetan Plateau to the...
of Mongolia
Mongolia
Mongolia is a landlocked country in East and Central Asia. It is bordered by Russia to the north and China to the south, east and west. Although Mongolia does not share a border with Kazakhstan, its western-most point is only from Kazakhstan's eastern tip. Ulan Bator, the capital and largest...
and northwestern China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
, though one possible sub-group, the elmisaurines, as well as the possible primitive species Microvenator celer lived in what is now North America. Definitive oviraptorids first appeared in the Cenomanian
Cenomanian
The Cenomanian is, in the ICS' geological timescale the oldest or earliest age of the Late Cretaceous epoch or the lowest stage of the Upper Cretaceous series. An age is a unit of geochronology: it is a unit of time; the stage is a unit in the stratigraphic column deposited during the corresponding...
stage of the late Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
Period (84 million years ago), although the possible oviraptorid Microvenator is known from the Aptian
Aptian
The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous epoch or series and encompasses the time from 125.0 ± 1.0 Ma to 112.0 ± 1.0 Ma , approximately...
stage of the Early Cretaceous
Early Cretaceous
The Early Cretaceous or the Lower Cretaceous , is the earlier or lower of the two major divisions of the Cretaceous...
Period. The last known members became extinct at the end of the Maastrichtian
Maastrichtian
The Maastrichtian is, in the ICS' geologic timescale, the latest age or upper stage of the Late Cretaceous epoch or Upper Cretaceous series, the Cretaceous period or system, and of the Mesozoic era or erathem. It spanned from 70.6 ± 0.6 Ma to 65.5 ± 0.3 Ma...
stage, 65.5 million years ago.
Description
The most characteristic feature of this group is the skull structure. Oviraptorids had short snouts and very deep mandibleMandible
The mandible pronunciation or inferior maxillary bone forms the lower jaw and holds the lower teeth in place...
s. Some taxa (Oviraptor, Citipati, Rinchenia) had a midline crest on top of the skull, resembling that of a cassowary
Cassowary
The cassowaries are ratites, very large flightless birds in the genus Casuarius native to the tropical forests of New Guinea, nearby islands and northeastern Australia. There are three extant species recognized today...
. Other distinguishing characters include a bony spike intruding on the mandibular fenestra, nostrils placed very high and far back on the snout, an extremely thin bony bar beneath the eye, and highly pneumatized skull bones. Like their relatives the caenagnathids, the jaws were edentulous (with no teeth), having instead two small bony projections on the top jaw.
Classification and species
The classification of the oviraptorids has been controversial. Most early studies divided oviraptorosaurs into two primary sub-groups, the Caenagnathidae and the Oviraptoridae. The Oviraptoridae was further divided into the small, short-armed, and crestless subfamily "Ingeniinae" (the name was preoccupied by an invertebrate group), and the larger, crested, long-armed Oviraptorinae. However, later phylogenetic studies showed that many traditional members of the Caenagnathidae were in fact more closely related to the crested oviraptorids. Because Caenagnathus
Caenagnathus
Caenagnathus is a genus of oviraptorosaurian dinosaur from the late Cretaceous . It is known from a single lower jaw, found in the Dinosaur Park Formation of Alberta, Canada.-Taxonomic history:...
itself is no longer considered part of this group, the subfamily is usually now termed the Elmisaurinae. The taxonomy below follows the one presented by Thomas Holtz, Jr. in 2010.
- Oviraptoridae
- Gigantoraptor erlianensisGigantoraptorGigantoraptor is a genus of giant oviraptorosaurian theropod dinosaur that lived 70 million years ago during the late Cretaceous Period. It was discovered in 2005 in the Iren Dabasu Formation, Erlian basin, in Inner Mongolia.-Discovery and naming:...
- Luoyanggia liudianensisLuoyanggiaLuoyanggia is a genus of oviraptorid dinosaur first reported from the Ruyang Basin, Henan Province of central China in 2009. The formation dates to the Cenomanian stage of the late Cretaceous period, around 96 million years ago. The type species is L. liudianensis....
- Microvenator celer
- Nomingia gobiensis
- Shixinggia oblita
- ElmisaurinaeElmisaurinaeElmisaurinae is a subfamily of bird-like maniraptoran theropod dinosaurs within the clade Oviraptorosauria or Oviraptoridae...
- OviraptorinaeOviraptorinaeOviraptorinae is a subfamily of bird-like maniraptoran theropod dinosaurs within the clade Oviraptoridae.-Classification and species: The classification of the oviraptorids has been controversial...
- Gigantoraptor erlianensis
Other possible oviraptorids include Nomingia gobienisis
Nomingia
Nomingia is a genus of oviraptorid theropod dinosaur hailing from the Late Cretaceous Bugin Tsav Beds of Mongolia.-Discovery and naming:...
, Shixinggia oblita
Shixinggia
Shixinggia is a genus of oviraptorosaurian dinosaur from the Late Cretaceous period of Shixing County, Guangdong, China. While no skull was recovered, the specimen is known from a fair amount of post-cranial material that shows it was a fairly derived oviraptorosaur , of superfamily Caenagnathoidea...
, and the early Microvenator celer
Microvenator
Microvenator is a genus of dinosaur from the Early Cretaceous Cloverly Formation in what is now south central Montana. Microvenator was an oviraptorosaurian theropod. The holotype fossil is an incomplete skeleton, most likely a juvenile, with a living length of about four feet. The adult size of...
. All three have been suggested to be oviraptorines, elmisaurines, or more primitive than either group.
Habitat
Almost all oviraptorids come from desertDesert
A desert is a landscape or region that receives an extremely low amount of precipitation, less than enough to support growth of most plants. Most deserts have an average annual precipitation of less than...
deposits of the Gobi Desert
Gobi Desert
The Gobi is a large desert region in Asia. It covers parts of northern and northwestern China, and of southern Mongolia. The desert basins of the Gobi are bounded by the Altai Mountains and the grasslands and steppes of Mongolia on the north, by the Hexi Corridor and Tibetan Plateau to the...
. Even in the late Cretaceous period, much of this area was desert, or at least very dry, habitat. In many of the localities where they are found, oviraptorids are among the most abundant dinosaurs present, second only to ankylosaurs and protoceratopsid
Protoceratopsid
A protoceratopsid is a dinosaur of the family Protoceratopsidae. The name 'protoceratopsid' is derived from Greek for 'first horned face'. They resembled and were closely related to, ceratopsids but were generally smaller and more primitive...
s. This is consistent with the idea that they were primarily herbivores, which tend to far outnumber carnivores in a given environment. Oviraptorids appear to have been far more abundant in arid habitats dominated mainly by small dinosaurs (such as those preserved in the Barun Goyot
Barun Goyot Formation
The Barun Goyot Formation , dating from the Late Cretaceous Period, is located within and is widely represented in the Gobi Desert basin, in the Ömnögovi Province of Mongolia....
and Djadochta Formation
Djadochta Formation
The Djadochta Formation is situated in central Asia and dates from the Late Cretaceous Period. Laid down in the early Campanian, possibly starting in the latest Santonian, it is dated somewhat uncertainly at about 84-75 mya...
s) than in wetter ecosystems where large dinosaurs are common (such as the Nemegt Formation
Nemegt Formation
The Nemegt Formation is a geological formation dating from the Late Cretaceous sedimentary from the Gobi Desert of Mongolia. It overlies and sometimes forms folds with the Barun Goyot Formation. It consists of river channel sediments and contains fossils of fish, turtles, crocodilians, birds and a...
). The same pattern holds true for protoceratopsids, indicating that both groups preferred dry, desert-like habitat, and fed mainly on the types of tough, low-growing plant life that grows in arid climates.
Diet
The diet of oviraptorids is not fully understood. Though some appear to have been at least partially carnivorous, they were probably primarily herbivorous.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 ceratopsia
Ceratopsia
Ceratopsia or Ceratopia is a group of herbivorous, beaked dinosaurs which thrived in what are now North America, Europe, and Asia, during the Cretaceous Period, although ancestral forms lived earlier, in the Jurassic. The earliest known ceratopsian, Yinlong downsi, lived between 161.2 and 155.7...
n dinosaur Protoceratops
Protoceratops
Protoceratops is a genus of sheep-sized herbivorous ceratopsian dinosaur, from the Upper Cretaceous Period of what is now Mongolia. It was a member of the Protoceratopsidae, a group of early horned dinosaurs...
. However, discoveries in the 1990s, including Citipati specimens clearly brooding (rather than predating) the same types of nests, and a Citipati embryo
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
inside the same type of egg preserved in these nests, showed that the "specialized egg thief" idea was incorrect. Still, some scientists have suggested that oviraptorids may have fed on shelled food items like eggs or shellfish. However, animals specialized for eating shelled food typically have broad, crushing beaks or teeth. In contrast, the jaws of oviraptorids had thin, sharp edges probably supporting shearing beaks, ill suited for cracking shells. Among other known animals, the beaks of oviraptorids most closely resemble those of herbivorous dicynodont
Dicynodont
Dicynodontia is a taxon of anomodont therapsids or mammal-like reptiles. Dicynodonts were small to large herbivorous animals with two tusks, hence their name, which means 'two dog tooth'...
synapsid
Synapsid
Synapsids are a group of animals that includes mammals and everything more closely related to mammals than to other living amniotes. They are easily separated from other amniotes by having an opening low in the skull roof behind each eye, leaving a bony arch beneath each, accounting for their name...
s, which are usually considered herbivorous. Their beaks also share similarities with the beaks of herbivorous parrot
Parrot
Parrots, also known as psittacines , are birds of the roughly 372 species in 86 genera that make up the order Psittaciformes, found in most tropical and subtropical regions. The order is subdivided into three families: the Psittacidae , the Cacatuidae and the Strigopidae...
s and tortoise
Tortoise
Tortoises are a family of land-dwelling reptiles of the order of turtles . Like their marine cousins, the sea turtles, tortoises are shielded from predators by a shell. The top part of the shell is the carapace, the underside is the plastron, and the two are connected by the bridge. The tortoise...
s.
Evidence of partial carnivory among some oviraptorines comes from a lizard skeleton preserved in the body cavity of the type specimen of Oviraptor and two hatchling Byronosaurus
Byronosaurus
Byronosaurus is a genus of troodontid dinosaur which lived during the Late Cretaceous Period. It was named for Byron Jaffe, "in recognition of his family's support for the Mongolian Academy of Sciences-American Museum of Natural History Paleontological Expeditions." The first example of...
skulls found in a Citipati nest. Some scientists have also suggested that some oviraptorids (especially the small-handed, weak-clawed "ingeniines") fed mainly on plant material.
Reproduction
Gobi Desert
The Gobi is a large desert region in Asia. It covers parts of northern and northwestern China, and of southern Mongolia. The desert basins of the Gobi are bounded by the Altai Mountains and the grasslands and steppes of Mongolia on the north, by the Hexi Corridor and Tibetan Plateau to the...
. Some specimens of the Oviraptor philoceratops
Oviraptor
Oviraptor is a genus of small Mongolian theropod dinosaur, first discovered by the paleontologist Roy Chapman Andrews, and first described by Henry Fairfield Osborn, in 1924...
and Citipati osmolskae
Citipati
Citipati is a genus of oviraptorid theropod dinosaur from the Late Cretaceous Period of what is now Mongolia . It is one of the best-known oviraptorids, thanks to a number of well-preserved skeletons, including several specimens found in brooding positions atop nests of eggs...
have been found in brooding
Avian incubation
Incubation refers to the process by which certain oviparous animals hatch their eggs, and to the development of the embryo within the egg. The most vital factor of incubation is the constant temperature required for its development over a specific period. Especially in domestic fowl, the act of...
positions. described in 1999, All of the nesting specimens are situated on top of egg clutches, with their limbs spread symmetrically on each side of the nest, front limbs covering the nest perimeter. This brooding posture is found today only in birds and supports a behavioral link between birds and theropod dinosaurs.
Oviraptorid eggs are shaped like elongated ovals (elongatoolithid) and resemble the eggs of ratite
Ratite
A ratite is any of a diverse group of large, flightless birds of Gondwanan origin, most of them now extinct. Unlike other flightless birds, the ratites have no keel on their sternum—hence the name from the Latin ratis...
birds (such as ostrich
Ostrich
The Ostrich is one or two species of large flightless birds native to Africa, the only living member of the genus Struthio. Some analyses indicate that the Somali Ostrich may be better considered a full species apart from the Common Ostrich, but most taxonomists consider it to be a...
es) in texture and shell structure. In the nest, eggs are typically found in pairs and arranged in concentric circles of up to three layers, with complete clutches consisting of as many of 22 eggs in some species. The eggs of Citipati are the largest known definitive oviraptorid eggs, at 18 cm. In contrast, eggs associated with Oviraptor are only up to 14 cm long.
Protoceratops
Protoceratops is a genus of sheep-sized herbivorous ceratopsian dinosaur, from the Upper Cretaceous Period of what is now Mongolia. It was a member of the Protoceratopsidae, a group of early horned dinosaurs...
and it was assumed that the oviraptorids were preying upon the eggs of the ceratopsians. It was not until 1993, when a Citipati embryo was discovered inside an egg of the type assigned to Protoceratops, that the error was corrected. Norell et al., who recognized the embryo as oviraptorid, assigned it to the genus Citipati. The egg containing the embryo was smaller than most known Citipati eggs at only 12 cm, though it was partially eroded and broken into three pieces, making an accurate estimate of its original size difficult. The embryo-bearing egg was otherwise identical to other oviraptorid eggs in shell structure and was found in an isolated nest, again arranged in a circular pattern.
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
described in 2005 was found to have two unlaid eggs within the pelvic canal. This suggests that, unlike modern crocodilia
Crocodilia
Crocodilia is an order of large reptiles that appeared about 84 million years ago in the late Cretaceous Period . They are the closest living relatives of birds, as the two groups are the only known survivors of the Archosauria...
ns, 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.
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 oviduct
Oviduct
In non-mammalian vertebrates, the passageway from the ovaries to the outside of the body is known as the oviduct. The eggs travel along the oviduct. These eggs will either be fertilized by sperm to become a zygote, or will degenerate in the body...
s. However, crocodilians produce multiple shelled eggs per oviduct at a time, whereas oviraptorosaurs, like birds, produced only one egg per oviduct at a time.
Feathers
Oviraptorids were probably featherFeather
Feathers are one of the epidermal growths that form the distinctive outer covering, or plumage, on birds and some non-avian theropod dinosaurs. They are considered the most complex integumentary structures found in vertebrates, and indeed a premier example of a complex evolutionary novelty. They...
ed, since some close relatives were found with feathers preserved (Caudipteryx
Caudipteryx
Caudipteryx is a genus of peacock-sized theropod dinosaurs that lived in the Aptian age of the early Cretaceous Period . They were feathered and remarkably birdlike in their overall appearance....
and possibly Protarchaeopteryx
Protarchaeopteryx
Protarchaeopteryx is a genus of turkey-sized feathered theropod dinosaur from China. Known from the Jianshangou bed of the Yixian Formation, it lived during the early Aptian age of the Early Cretaceous, approximately 124.6 million years ago...
). Another finding pointing to this is the discovery in Nomingia
Nomingia
Nomingia is a genus of oviraptorid theropod dinosaur hailing from the Late Cretaceous Bugin Tsav Beds of Mongolia.-Discovery and naming:...
of a pygostyle
Pygostyle
Pygostyle refers to a number of the final few caudal vertebrae fused into a single ossification, supporting the tail feathers and musculature. In modern birds, the rectrices attach to these....
, 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. Finally, the arm position of the brooding Citipati would have been far more effective if feathers were present to cover the eggs.
Pathology
The brooding oviraptorid specimen IGM 100/979 showed a callusCallus
A callus is an especially toughened area of skin which has become relatively thick and hard in response to repeated friction, pressure, or other irritation. Rubbing that is too frequent or forceful will cause blisters rather than allow calluses to form. Since repeated contact is required, calluses...
and possible longitudinal
Longitudinal
Longitudinal may refer to:* Longitudinal engine, an internal combustion engine in which the crankshaft is oriented along the long axis of the vehicle, front to back...
groove leftover from a healed fracture of the right ulna
Ulna
The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form and runs parallel to the radius, which is shorter and smaller. In anatomical position The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form...
. Other oviraptorids have had pathological features reported in their phalanges but these have not been described in detail in the scientific literature.