68-478: 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
136-608: A dromaeosaurid , was too heavy to fly but still had wings with feathers required for flying, which suggests its ancestors had the ability for aerial locomotion. Other groups, like the Oviraptorosauria who had a tail with a tail fan of feathers with caudal anatomy resembling a pygostyle , are not known to have been capable of flight, but some scientists, such as Gregory S. Paul , have suggested that they could be descended from ancestors which flew. Paul has gone as far as to propose that Therizinosauria , Alvarezsauroidea , and
204-407: A trochanteric crest . An elongated, backwards-pointing pubic bone is present in therizinosauroids, dromaeosaurids, avialans, and the basal troodontid Sinovenator , which suggests that the propubic condition in advanced troodontids and oviraptorosaurs is a reversal. Turner et al. (2007) named seven synapomorphies that diagnose Maniraptora. Modern pennaceous feathers and remiges are known in
272-493: A 2001 paper. Their proposed definition for the group was "the clade stemming from the first panavian with ... remiges and rectrices , that is, enlarged, stiff-shafted, closed-vaned (= barbules bearing hooked distal pennulae), pennaceous feathers arising from the distal forelimbs and tail". Ancestral morphology relating to pennaceous feathers suggests that basal species of Pennaraptora were capable of scansorial locomotion and gliding, and further evolution of said adaptation within
340-469: 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 roof of the mouth. The classification of the oviraptorids has been controversial. Most studies divide oviraptorosaurs into two primary sub-groups,
408-417: A closer relative of the "ingeniines" and this traditional division into crestless and crested forms artificial. Other possible oviraptorids include Nomingia gobiensis , Gigantoraptor erlianensis , Jiangxisaurus ganzhouensis and Shixinggia oblita . All four have been suggested to be oviraptorids, caenagnathids, or more primitive than either group. The below cladogram was found in the description of
476-500: A feathered bird-like predator) is a clade within Maniraptora, defined as the most recent common ancestor of Oviraptor philoceratops , Deinonychus antirrhopus , and Passer domesticus (the house sparrow), and all descendants thereof, by Foth et al. , 2014. The clade "Aviremigia" was conditionally proposed along with several other apomorphy -based clades relating to birds by Jacques Gauthier and Kevin de Queiroz in
544-503: A long, backwards-pointed pubis and short ischia were present in Scansoriopteryx , a scansoriopterygid. The authors considered it to be more primitive than true theropods, and hypothesized that maniraptorans may have branched off from theropods at a very early point, or may even have descended from pre-theropod dinosaurs. Zhang et al. , in describing the closely related or conspecific specimen Epidendrosaurus (now considered
612-549: A nest at the Ukhaa Tolgod locality of the highly fossiliferous Djadokhta Formation , Gobi Desert , during the Mongolian Academy of Sciences-American Museum of Natural History paleontological project. The expedition also discovered numerous mammal, lizard, theropod, ceratopsian and ankylosaurid fossils remains at this locality, with the addition of at least five types of fossil eggs in nests. The oviraptorid embryo
680-450: A number of discoveries made during the first decade of the 21st century, as well as re-evaluation of older evidence, began to suggest that maniraptorans were a primarily omnivorous group, including a number of sub-groups that ate mainly plants, insects, or other food sources besides meat. Additionally, phylogenetic studies of maniraptoran relationships began to more consistently show that herbivorous or omnivorous groups were spread throughout
748-473: A number of well-preserved specimens, including individuals found in brooding positions atop nests of eggs, though most of them were initially referred to the related Oviraptor . These nesting specimens have helped to solidify the link between non-avian dinosaurs and birds . Citipati was among the largest oviraptorids; it is estimated to have been around 2.5–2.9 m (8.2–9.5 ft) in length and to have weighed 75–110 kg (165–243 lb). Its skull
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#1732783254729816-461: A region called Camel's Humps, at the Death Row sublocality. This new specimen was labelled as IGM 100/1004 and nicknamed "Big Auntie". The excavation lasted several days of work and a filming crew registered some of the excavation progress through video-documentary and photography. The professional team had to remove some of the sediments surrounding the specimen as the terrain was irregular and it
884-772: A slightly different cladogram. 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. Nankangia Oviraptor Yulong Wulatelong Rinchenia Tongtianlong Ganzhousaurus Citipati Zamyn Khondt oviraptorid Huanansaurus Corythoraptor Shixinggia Khaan Conchoraptor Machairasaurus Nemegtomaia Heyuannia huangi Heyuannia yanshini Banji Jiangxisaurus Oksoko The diet of oviraptorids
952-570: A small notch preserved on the right jugal, just beneath the orbit, of the holotype skull of Citipati . This anomaly was likely produced by external damage, leaving a small injury. Citipati is vastly known from the Ukhaa Tolgod locality of the Djadokhta Formation , which is dated around 71 million to 75 million years ago ( Late Cretaceous ). This formation is separated into a lower Bayn Dzak Member and upper Turgrugyin Member, of which
1020-685: A squared appearance. Citipati is often referred to the subfamily Oviraptorinae along with Oviraptor . However, in 2020, Gregory F. Funston and colleagues found Oviraptor to be more basal, so they named a new subfamily Citipatiinae . The cladogram below follows their analysis: Nankangia Oviraptor Yulong Wulatelong Rinchenia Tongtianlong Ganzhousaurus Citipati Zamyn Khondt oviraptorid Huanansaurus Corythoraptor Shixinggia Khaan Conchoraptor Machairasaurus Nemegtomaia Heyuannia huangi Heyuannia yanshini Banji Jiangxisaurus Oksoko A 2022 study of
1088-416: A stout, toothless beak. Perhaps the most distinctive feature of Citipati was its tall crest, superficially similar to that of a modern cassowary . The crest was relatively low in C. osmolskae formed by the premaxilla and nasal bones of the skull, with a nearly vertical front margin grading into the beak. In contrast, the crest of IGM 100/42 was taller with a prominent notch in the front margin, creating
1156-482: A synonym of Scansoriopteryx ), did not report any of the primitive traits mentioned by Czerkas and Yuan, but did find that the shoulder blade of Epidendrosaurus appeared primitive. Despite this, they placed Epidendrosaurus firmly within Maniraptora due to a number of synapomorphies. Scientists traditionally assumed that maniraptorans were ancestrally hypercarnivorous , that is, that most non-avialan species primarily ate and hunted only other vertebrates . However,
1224-418: Is among the oviraptorid species that preserve nesting specimens. Citipati laid elongatoolithid eggs in a circular mound-shaped nest, where the parents brooded the eggs by sitting on the nest with their arms covering the nest perimeter. Both arms and tail were covered in long feathers, which likely protected both juveniles and eggs from weather . Citipati may have been an omnivorous oviraptorid, given that
1292-522: Is composed of a nearly complete skeleton and was found in a badly weathered semi-circular nest, which also included two perinate (hatchlings or embryos close to hatching) skulls less than 5 cm (50 mm) of an unknown dromaeosaurid taxon. One of these skulls was reported to preserve portions of an eggshell. Both embryonic oviraptorid and dromaeosaurid skulls were briefly described by the paleontologist Mark A. Norell and colleagues in 1993, who considered this oviraptorid embryo to be closely related to
1360-458: Is not fully understood. Though some appear to have been at least partially carnivorous, they were probably primarily herbivorous or omnivorous. 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 ceratopsian dinosaur Protoceratops . However, discoveries in the 1990s, including Citipati specimens clearly brooding (rather than preying on)
1428-551: The Djadokhta Formation . Since the type skull and body remains of Oviraptor are crushed and partially preserved, the Zamyn Khondt oviraptorid had become the quintessential depiction of the former, even appearing in scientific literature with the label Oviraptor philoceratops . Clark with team have pointed out that this distinctive-looking, tall-crested oviraptorid has more features of the skull in common with Citipati than it does with Oviraptor . Though being different in
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#17327832547291496-562: The Late Cretaceous period , about 75 million to 71 million years ago. It is mainly known from the Ukhaa Tolgod locality at the Djadochta Formation , where the first remains were collected during the 1990s. The genus and type species Citipati osmolskae were named and described in 2001. A second species from the adjacent Zamyn Khondt locality may also exist. Citipati is one of the best-known oviraptorids thanks to
1564-492: The Tibetan Buddhism folklore, Citipati , which is often depicted as a humanoid skeleton. The specific name, osmolskae , is in honor to the noted Polish paleontologist Halszka Osmólska , whose work dealt extensively with Mongolian theropods. Though the first specimen of Citipati (IGM 100/971) was briefly reported and discussed, Norell and colleagues in 2001 provided an extensive description of this specimen. As
1632-477: The paleontologists James M. Clark , Mark A. Norell and Rinchen Barsbold named the new genus and type species Citipati osmolskae based on the now regarded holotype IGM 100/978, and referred specimens IGM 100/971 (embryo) with 100/979 ("Big Mama"). The generic name, Citipati , is formed from the Sanskrit words citi (meaning funeral pyre) and pati (meaning lord) in reference to the lord of cemeteries in
1700-520: The scansoriopterygids , Pedopenna , and Yixianosaurus . In 1993, Perle and colleagues coined the name Metornithes to include alvarezsaurids and modern birds, which the researchers believed were members of the Avialae. This group was defined as a clade by Luis Chiappe in 1995 as the last common ancestor of Mononykus and modern birds, and all its descendants. Pennaraptora (Latin penna "bird feather" + raptor "thief", from rapere "snatch";
1768-401: The sister taxon of Citipati . Citipati was a large-bodied oviraptorid, with the largest individuals being emu -sized animals; it has been estimated at 2.5–2.9 m (8.2–9.5 ft) in length with a weight between 75–110 kg (165–243 lb), and was one of the largest known oviraptorosaurs until the description of Gigantoraptor . Based on their humeral lengths, IGM 100/1004
1836-411: The "primitive" forward-pointing hip seen in advanced troodontids and oviraptorosaurs is an evolutionary reversal, and that these groups evolved from ancestors with backward-pointing hips. Holtz and Osmólska (2004) diagnosed the clade Maniraptora based on the following characters: reduced or absent olecranon process of the ulna , greater trochanter and cranial trochanter of the femur fused into
1904-544: 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
1972-493: The Elmisauridae, 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 ( Oviraptor + Citipati ). Some phylogenetic studies have shown that Oviraptor is the most primitive known oviraptorid, thus making Citipati
2040-461: The Maniraptora, rather than representing a single side-branch as previously thought. This led scientists such as Lindsay Zanno to conclude that the ancestral maniraptoran must have been omnivorous, giving rise to several purely herbivorous groups (such as the therizinosaurs, primitive oviraptorosaurs, and some avialans) and that, among non-avians, only one group reverted to pure carnivores (the dromaeosaurids). Most other groups fell somewhere in between
2108-481: The Ukhaa Tolgod locality of the Djadokhta Formation, in a sublocality known as Ankylosaur Flats. This new specimen was labelled under the specimen number IGM 100/979 and includes a partial skeleton comprising some ribs and partial limbs but lacking the skull, neck and tail. It was found in a nesting pose, sitting atop a nest of elongatoolithid eggs with folded forelimbs and crouched hindlimbs. Similar to
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2176-418: The advanced maniraptoran group Aviremigia . More primitive maniraptorans, such as therizinosaurs (specifically Beipiaosaurus ), preserve a combination of simple downy filaments and unique elongated quills. Simple feathers are known from more primitive coelurosaurs such as Sinosauropteryx prima , and possibly from even more distantly related species such as the ornithischian Tianyulong confuciusi and
2244-411: The beaks of oviraptorids most closely resemble those of herbivorous dicynodont synapsids , which are usually considered herbivorous.(This leads to the possibility that these animals are omnivorous). Their beaks also share similarities with the beaks of herbivorous parrots and tortoises . Maniraptora Maniraptora is a clade of coelurosaurian dinosaurs which includes the birds and
2312-680: The bite force of Citipati and comparisons with other oviraptorosaurs such as Incisivosaurus , Khaan , and Conchoraptor suggests that Citipati had a very strong bite force, scored between 349.3 N and 499.0 N. The moderate jaw gape seen in oviraptorosaurs is indicative of herbivory in the majority of the group, but it is clear they were likely feeding on much tougher vegetation than other herbivorous theropods in their environment, such as ornithomimosaurs and therizinosaurs were able to. The examinations suggest oviraptorosaurs may have been powerful-biting generalists or specialists that partook of niche partitioning both in body size and jaw function. Of
2380-479: The clade would eventually give rise to the origin of flight in avian species. The following cladogram follows the results of a phylogenetic study by Cau (2020). † Alvarezsauroidea [REDACTED] † Therizinosauridae [REDACTED] † Oviraptorosauria [REDACTED] † Dromaeosauridae [REDACTED] † Troodontidae [REDACTED] Avialae [REDACTED] In 2002, Czerkas and Yuan reported that some maniraptoran traits, such as
2448-537: The crest shape of the skull, the Zamyn Khondt oviraptorid is similar to Citipati in the shape of the narial region and premaxilla morphology. They considered this oviraptorid to belong to the genus, however, they could neither confirm nor disregard that this specimen represents a second species of Citipati . Lü Junchang and colleagues in 2004 found this specimen to be closely related to Oviraptor , Phil Senter with team in 2007 placed it close to neither genus, and in 2020 Gregory F. Funston and colleagues found it to be
2516-441: The description of "Big Mama" noted that the right ulna was badly broken but healed , leaving a prominent callus and possible elongated groove over the injury . As the ulna features positive signs of healing, in 2019 Leas Hearn and team suggested that this individual managed to survive an injury that would have interfered with foraging for several weeks in order to lay and incubate its nest. In 2002 Clark with team reported
2584-492: The description was published prior to the formal naming of Citipati , Norell and team tentatively referred this small embryo to a "new large species from Ukhaa Tolgod"—in fact, later known as Citipati osmolskae —based on the shared tall premaxilla morphology among specimens. The more famous IGM 100/979 was extensively described by Clark and team in 1999, also prior to the naming of Citipati . They considered this specimen to be most similar and closely related to Oviraptor than to
2652-439: The earlier branch-based definition. The branch-based definition usually includes the major groups Dromaeosauridae , Troodontidae , Oviraptorosauria , Therizinosauria , and Avialae . Other taxa often found to be maniraptorans include the alvarezsaurs and Ornitholestes . Several taxa have been assigned to the Maniraptora more definitively, though their exact placement within the group remains uncertain. These forms include
2720-413: The early named Oviraptor , and also as an evidence supporting that oviraptorids were brooding animals. The two perinates would be later identified as individuals belonging to the troodontid Byronosaurus . During the same year 1993, expeditions of the paleontological project of the Mongolian Academy of Sciences-American Museum of Natural History discovered a large adult oviraptorid specimen also from
2788-572: The embryonic specimen, IGM 100/979 was considered to be an indeterminate oviraptorid closely related to Oviraptor . The specimen shortly became famous and was nicknamed as "Big Mama" by The New York Times press. A larger and more complete specimen, catalogued as IGM 100/978, was found in 1994 also from the Ankylosaur Flats sublocality by the American Museum–Mongolian Academy of Sciences field expeditions. The specimen
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2856-469: The endocranium anatomy. In 2003 Amy Davidson described the process in which the holotype was prepared , later supplemental by Christina Bisulca and team in 2009 describing conservation treatments of broken bones. The Zamyn Khondt oviraptorid is a well-known oviraptorid represented by a single and rather complete specimen (IGM 100/42) collected from the Zamyn Khondt (also spelled as Dzamin Khond) locality of
2924-513: The flying pterosaurs . Thus it appears as if some form of feathers or down-like integument would have been present in all maniraptorans, at least when they were young. Maniraptora is the only dinosaur group known to include flying members, though how far back in this lineage flight extends is controversial. Powered and/or gliding flight is believed to have been present in some types of non-avialan paravians, including dromaeosaurids, such as Rahonavis and Microraptor . Zhenyuanlong suni ,
2992-483: The fossil record during the Jurassic Period (see Eshanosaurus ), and survive today as living birds. Maniraptorans are characterized by long arms and three-fingered hands (though reduced or fused in some lineages), as well as a "half-moon shaped" (semi- lunate ) bone in the wrist ( carpus ). In 2004, Tom Holtz and Halszka Osmólska pointed out six other maniraptoran characters relating to specific details of
3060-587: The genus Anzu . Caenagnathidae Nankangia jiangxiensis Yulong mini Nomingia gobiensis Oviraptor philoceratops Rinchenia mongoliensis Zamyn Khondt oviraptorid Citipati osmolskae Wulatelong gobiensis Banji long Shixinggia oblita Jiangxisaurus ganzhouensis Ganzhousaurus nankangensis Nemegtomaia barsboldi Machairasaurus leptonychus Conchoraptor gracilis Khaan mckennai Ingenia yanshini Heyuannia huangi In 2020, during their description of Oksoko , Funston et al. recovered
3128-413: The hypothesis that it and other oviraptorids had feathered forelimbs. Thomas P. Hopp and Mark J. Orsen in 2004 analyzed the brooding behavior of extinct and extant dinosaur species, including oviraptorids, in order to evaluate the reason for the elongation and development of wing and tail feathers . Given that IGM 100/979 was found in a very avian-like posture, with the forelimbs in a near-folded posture and
3196-494: The largest known definitive oviraptorid eggs, at 18 cm. In contrast, eggs associated with Oviraptor are only up to 14 cm long. The two nesting specimens of Citipati 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. The nesting position of Citipati also supports
3264-498: The most well-known species and complete specimens found only in the Gobi Desert of Mongolia and northwestern China . The most characteristic feature of this group is the skull structure. Oviraptorids had short snouts and very deep mandibles . Some taxa (such as Citipati , Corythoraptor , Rinchenia ) had a midline crest on top of the skull, resembling that of a cassowary . Other distinguishing characteristics include
3332-439: The name Maniraptora, which means "hand snatchers" in relation to their 'seizing hands'). In 1994, Thomas R. Holtz attempted to define the group based on the characteristics of the hand and wrist alone (an apomorphy-based definition), and included the long, thin fingers, bowed, wing-like forearm bones, and half-moon shaped wrist bone as key characters. Most subsequent studies have not followed this definition, however, preferring
3400-555: The naming of the taxon and during that time, the specimen had not been completely prepared . The skull anatomy of the specimen was later described by Clark and colleagues in 2002, the furcula morphology in 2009 by Sterling J. Nesbitt with team, and the caudal vertebrae by W. Scott Persons and colleagues in 2014 who noted the presence of a pygostyle . Subsequent descriptions have been published in 2018 by Norell and team describing and illustrating some cervical vertebrae and uncinate processes, and Amy M. Balanoff and colleagues describing
3468-586: The non-avian dinosaurs that were more closely related to them than to Ornithomimus velox . It contains the major subgroups Avialae , Dromaeosauridae , Troodontidae , Oviraptorosauria , and Therizinosauria . Ornitholestes and the Alvarezsauroidea are also often included. Together with the next closest sister group, the Ornithomimosauria , Maniraptora comprises the more inclusive clade Maniraptoriformes . Maniraptorans first appear in
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#17327832547293536-413: The non-maniraptoran group Ornithomimosauria also descended from flying ancestors. The Maniraptora was originally named by Jacques Gauthier in 1986, for a branch-based clade defined as all dinosaurs closer to modern birds than to the ornithomimids . Gauthier noted that this group could be easily characterized by their long forelimbs and hands, which he interpreted as adaptations for grasping (hence
3604-453: The one functional ovary in birds, and were thus limited in the numbers of eggs each individual could produce. [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] Citipati Citipati ( [ˈtʃiːt̪ɪpət̪i] ; meaning "funeral pyre lord") is a genus of oviraptorid dinosaur that lived in Asia during
3672-419: The other oviraptorids known at that time. Despite being discovered in 1995, the specimen IGM 100/1004 remained partially figured and largely undescribed for years until its formal referral to the taxon Citipati osmolskae in 2018 by Norell and team. The largest and most complete specimen of Citipati is represented by the holotype IGM 100/978, however, it was preliminarily described and figured in 2001 during
3740-422: The oviraptorids examined in this study, Citipati had one of the most powerful bites, but its biting mechanics were unique among the oviraptorosaurs investigated. 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. Two skulls belonging to very young or embryonic Byronosaurus were found associated with
3808-474: The pectoral region, belly, and feet in contact with the eggs, Hopp and Orsen indicated that long pennaceous feathers and a feather covering were most likely present in life. The "wings" and tail of oviraptorids would have granted protection for the eggs and hatchlings against climate factors like the sunlight , wind , and rainfalls . However, the arms of this specimen were not extremely folded as in some modern birds, instead, they are more extended resembling
3876-457: The remains of two young individuals of the contemporaneous troodontid Byronosaurus were found in a nest, likely preyed and brought by an adult Citipati to feed its hatchlings. It is also possible that these small Byronosaurus were hatched by the Citipati as a product of nest parasitism . In 1993, a small fossilized oviraptorid embryo, labelled as specimen IGM 100/971, was discovered in
3944-479: The same nest as the first Citipati embryo. It is possible that these tiny troodontids were preyed upon by the Citipati to feed its nest. Alternately, Mark Norell suggested that the juvenile troodonts were raiding the Citipati nest, or even that an adult Byronosaurus had laid eggs in a Citipati nest as an act of nest parasitism . Although fossilized dinosaur eggs are rare, Citipati eggs and oviraptorid eggs in general, are relatively well known. Along with
4012-534: 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,
4080-444: The skeleton. Unlike most other saurischian dinosaurs, which have pubic bones that point forward, several groups of maniraptorans have an ornithischian -like backwards-pointing hip bone. A backward-pointing hip characterizes the therizinosaurs , dromaeosaurids , avialans , and some primitive troodontids . The fact that the backward-pointing hip is present in so many diverse maniraptoran groups has led most scientists to conclude that
4148-561: The style of large flightless birds like the ostrich . The extended position of the arm is also similar to the brooding behavior of this bird, which is known to nest in large clutches like oviraptorids. Based on the forelimb position of nesting oviraptorids, Hopp and Orsen proposed brooding as the ancestral reason behind wing and tail feather elongation, as there was a greater need to provide optimal protection for eggs and juveniles. In 2014, W. Scott Persons and colleagues suggested that oviraptorosaurs were secondarily flightless and several of
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#17327832547294216-448: The traits in their tails may indicate a propensity for display behaviour , such as courtship display . The tail of several oviraptorosaurs and oviraptorids ended in pygostyles , a bony structure at the end of the tail that, at least in modern birds, is used to support a feather fan. Furthermore, the tail was notably muscular and had a pronounced flexibility, which may have aided in courtship movements. Clark and colleagues in 1999 during
4284-644: The two extremes, with alvarezsaurids and some avialans being insectivorous, and with advanced oviraptorosaurs and troodontids being omnivorous. A 2023 study analyzing fossil eggshells assigned to Troodon with clumped isotope thermometry found that Troodon , and likely other non-avian maniraptorans, had a slowed calcification of eggs akin to that of most reptiles. This contrasts with the rapid calcification of eggs found in modern birds, indicating that most maniraptorans aside from birds retained this basal trait. This would also indicate that most non-avian maniraptorans possessed two functional ovaries , contrasting with
4352-444: The two known nesting specimens, dozens of isolated oviraptorid nests have been uncovered in the Gobi Desert . Citipati eggs are elongatoolithid , which are shaped like elongated ovals and resemble the eggs of ratites in texture and shell structure. In the nest, Citipati eggs are typically arranged in concentric circles of up to three layers, and a complete clutch may have consisted of as many of 22 eggs. The eggs of Citipati are
4420-487: Was about 11% larger than IGM 100/979. Like other oviraptorids, Citipati had an unusually long neck and shortened tail compared to most other theropods. The presence of a pygostyle and the brooding pose in specimens of Citipati indicate the presence of large wing and tail feathers , and plumage . Other oviraptorids and oviraptorosaurs are also known to have been feathered. Its skull was unusually short and highly pneumatized (riddled with air-spaced openings), ending in
4488-431: Was highly pneumatized , short, and had a characteristic crest formed by the premaxilla and nasal bones. Both upper and lower jaws were toothless and developed a horny beak . The tail ended in a pygostyle (the fusion of the last caudal vertebrae), which is known to support large rectrices . The taxon is classified as an oviraptorid, a group of very bird-like feathered dinosaurs that had robust, parrot-like jaws. It
4556-501: Was too heavy to be safely transported to the escarpment. As most fossils of the Ukhaa Tolgod locality have a relatively good preservation and exposure, the lack of associated nests argues against the possibility for this sublocality to be an oviraptorid nesting site. IGM 100/1004 is slightly more complete than 100/979; it preserves the entire cervical series with the exception of the atlas and axis , dorsal vertebrae with thoracic ribs, partial limbs and some sacral vertebrae . In 2001,
4624-415: Was unearthed as a single individual not associated with eggs, and it is represented by a nearly complete skeleton including the skull and much of the postcranial elements. However, it was initially identified as a specimen of Oviraptor . In 1995, the Mongolian Academy of Sciences-American Museum of Natural History expedition discovered a second nesting oviraptorid specimen from the Ukhaa Tolgod locality, in
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