Citipati
Citipati ([ˈtʃiːt̪ɪpət̪i]; meaning "funeral pyre lord") is a genus of oviraptorid dinosaur that lived in Asia during 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 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 75–83 kg (165–183 lb). Its skull 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 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 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 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 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 the early named Oviraptor, and also as an evidence supporting that oviraptorids were brooding animals.[1] The two perinates would be later identified as individuals belonging to the troodontid Byronosaurus.[2]
