Citipati is one of the best-known oviraptorids thanks to 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.

In 1993, a small fossilized oviraptorid embryo, labelled as specimen IGM 100/971, was discovered in 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.

[2] 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 the Ukhaa Tolgod locality of the Djadokhta Formation, in a sublocality known as Ankylosaur Flats.

[4] 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.

[5] 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 a region called Camel's Humps, at the Death Row sublocality.

The professional team had to remove some of the sediments surrounding the specimen as the terrain was irregular and it was too heavy to be safely transported to the escarpment.

The specific name, osmolskae, is in honor to the noted Polish paleontologist Halszka Osmólska, whose work dealt extensively with Mongolian theropods.

[10] 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.

[13][7] Its skull was unusually short and highly pneumatized (riddled with air-spaced openings), ending in a stout, toothless beak.

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.

The cladogram below follows their analysis:[20] 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 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.

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.

The "wings" and tail of oviraptorids would have granted protection for the eggs and hatchlings against climate factors like the sunlight, wind, and rainfalls.

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.

[13] Clark and colleagues in 1999 during 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.

[10] 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.

[28] In 2002 Clark with team reported a small notch preserved on the right jugal, just beneath the orbit, of the holotype skull of Citipati.

Characteristic lithology across the formation include reddish-orange and pale orange to light gray, medium to fine-grained sands and sandstones, and caliche, with better exposures represented at Ukhaa Tolgod.

[29][30] Other dinosaurs known from Ukhaa Tolgod include alvarezsaurids Kol and Shuvuuia;[31][32] ankylosaurid Minotaurasaurus;[33] birds Apsaravis and Gobipteryx;[34][35] dromaeosaurid Tsaagan;[36] fellow oviraptorid Khaan;[37] troodontids Almas and Byronosaurus;[38][39] and an undescribed protoceratopsid closely related to Protoceratops.