Citipati

Citipati

Overview
Citipati is a genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of oviraptorid theropod 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...

 from 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 of what is now 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...

 (specifically, the Djadokhta Formation of Ukhaa Tolgod, 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...

). It is one of the best-known oviraptorids, thanks to a number of well-preserved skeletons, including several specimens 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 atop nests of eggs. These nesting specimens have helped to solidify the link between non-avian dinosaurs and bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s.

The type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...

, Citipati osmolskae, was described by James M.
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Encyclopedia
Citipati is a genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of oviraptorid theropod 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...

 from 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 of what is now 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...

 (specifically, the Djadokhta Formation of Ukhaa Tolgod, 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...

). It is one of the best-known oviraptorids, thanks to a number of well-preserved skeletons, including several specimens 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 atop nests of eggs. These nesting specimens have helped to solidify the link between non-avian dinosaurs and bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s.

The type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...

, Citipati osmolskae, was described by James M. Clark, Mark Norell, and Rinchen Barsbold in 2001. A second, as yet unnamed species may also exist. Citipati is often confused with the similar Oviraptor
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...

.

Description



The largest Citipati were emu
Emu
The Emu Dromaius novaehollandiae) is the largest bird native to Australia and the only extant member of the genus Dromaius. It is the second-largest extant bird in the world by height, after its ratite relative, the ostrich. There are three subspecies of Emus in Australia...

-sized animals and, at about 3 meters (9 ft) long, were the largest known oviraptorids until Gigantoraptor
Gigantoraptor
Gigantoraptor 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:...

was described in 2007. Like other oviraptorids, Citipati had an unusually long neck and shortened tail, compared to most other theropods. Its skull was unusually short and highly pneumatized (riddled with openings in the bone structure), ending in a stout, toothless beak. Perhaps the most distinctive feature of Citipati was its tall crest, superficially similar to that of a modern 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...

. The crest was relatively low in the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...

, C. osmolskae, with a nearly vertical front margin grading into the beak. In contrast, the crest of one referred specimen which has not yet been assigned a specific name (provisionally labeled C. sp.) was taller, with a prominent notch in the front margin, creating a squared appearance.

Name


The name Citipati is formed from the Sanskrit
Sanskrit
Sanskrit , is a historical Indo-Aryan language and the primary liturgical language of Hinduism, Jainism and Buddhism.Buddhism: besides Pali, see Buddhist Hybrid Sanskrit Today, it is listed as one of the 22 scheduled languages of India and is an official language of the state of Uttarakhand...

 words citi, meaning 'funeral pyre' and pati meaning 'lord'. In Tibet
Tibet
Tibet is a plateau region in Asia, north-east of the Himalayas. It is the traditional homeland of the Tibetan people as well as some other ethnic groups such as Monpas, Qiang, and Lhobas, and is now also inhabited by considerable numbers of Han and Hui people...

an Buddhist folklore, the citipati were two monks who were beheaded by a thief, while deep in a meditative trance. The citipati are often depicted as a pair of dancing skeletons surrounded by flame, hence the application of the name to the beautifully preserved oviraptorid skeletons. The type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...

 of Citipati, C. osmolskae, was named by Clark et al., in honor of Halszka Osmólska
Halszka Osmólska
Halszka Osmólska was a Polish paleontologist who had specialized in Mongolian dinosaurs.She was born in Poznań. A member of the 1965 and 1970 Polish–Mongolian expeditions to the Gobi Desert, she described many finds from these rocks, often with Teresa Maryańska...

, a noted paleontologist whose work has dealt extensively with oviraptorids and other Mongolian theropods.

Confusion with Oviraptor



Since the type skull of Oviraptor
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...

is so poorly preserved and crushed, another oviraptorid specimen (IGM or GIN 100/42) had become the quintessential depiction of that dinosaur, even appearing in scientific papers with the label Oviraptor philoceratops. However, this distinctive-looking, tall-crested species has more features of the skull in common with Citipati than it does with Oviraptor and it may represent a second species of Citipati or possibly an entirely new genus, pending further study. Additionally, the nesting oviraptorid specimens had gained widespread attention before they were actually referred to Citipati. While usually labeled simply "oviraptorids", they have on occasion been confused with Oviraptor itself. The fact that the first Oviraptor specimen was found on a nest as well confused the matter further. As it stands, most popular illustrations of Oviraptor actually depict Citipati and the present material available for Oviraptor itself is too fragmentary to be reliably reconstructed.

Nesting, eggs, and embryos


At least four Citipati specimens 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, the most famous of which, a large specimen nicknamed "Big Mamma", was first announced (but not named) in 1995, described in 1999, and referred to the genus Citipati in 2001. 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. The nesting position of Citipati also supports the hypothesis that it and other oviraptorids had feathered forelimbs. With the 'arms' spread along the periphery of the nest, a majority of eggs would not be covered by the animal's body unless an extensive coat of feathers was present.

Although fossilized dinosaur eggs are rare, Citipati eggs and oviraptorid eggs in general, are relatively well known. Along with the four known nesting specimens, dozens of isolated oviraptorid nests have been uncovered 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...

. Citipati 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...

s 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 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
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 in 2001, based on the vertical orientation of the premaxilla
Premaxilla
The incisive bone is the portion of the maxilla adjacent to the incisors. It is a pair of small cranial bones at the very tip of the jaws of many animals, usually bearing teeth, but not always. They are connected to the maxilla and the nasals....

 (a bone structure at the tip of the jaw), a feature found only in 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.

Two skulls belonging to very young or embryonic 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...

were found associated with the same nest as the first Citipati embryo. It is possible that these tiny troodontids
Troodontidae
Troodontidae is a family of bird-like theropod dinosaurs. During most of the 20th century, troodontid fossils were few and scrappy and they have therefore been allied, at various times, with many dinosaurian lineages...

 were preyed upon by the Citipati. 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 in an act of nest parastism.

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