Kosmoceratops () is a genus of ceratopsid dinosaur that lived in North America about 76–75.9 million years ago during the Late Cretaceous period. Specimens were discovered in Utah in the Kaiparowits Formation of the Grand Staircase–Escalante National Monument in 2006 and 2007, including an adult skull and postcranial skeleton and partial subadults. In 2010, the adult was made the holotype of the new genus and species Kosmoceratops richardsoni; the generic name means "ornate horned face", and the specific name honors Scott Richardson, who found the specimens. The find was part of a spate of ceratopsian discoveries in the early 21st century, and Kosmoceratops was considered significant due to its elaborate skull ornamentation. Kosmoceratops had an estimated length of 4.5 m (15 ft) and a weight of 1.2 t (1.3 short tons). As a ceratopsid, it would have been quadrupedal with a heavily constructed skeleton. It had a triangular beak with a pointed tip and a blade-like nasal horn with a flattened upper portion. While the horns above the eyes were oriented forwards or hindwards in most of its relatives, the horns of Kosmoceratops pointed up and to the sides, then downwards, ending in pointed tips. The neck frill was short from front to back, with small parietal fenestrae (openings through the frill), and ten hook-like epiossifications on the hind margin, with eight curving forwards and two curving to the sides. With fifteen well-developed horns and horn-like structures, it possessed the most ornate skull of any known dinosaur species. Kosmoceratops was a chasmosaurine ceratopsid and was originally suggested to be closely related to Vagaceratops (which also had forward-curving epiossifications on the back of the frill) but this has been debated, some authors finding the latter closer to Chasmosaurus. Kosmoceratops is also considered closely related to Spiclypeus, which had a similar frill. Studies of bone histology show that Kosmoceratops grew rapidly and had an elevated metabolism, similar to modern birds and mammals. The teeth of ceratopsids were adapted to processing fibrous plants; coprolites (fossilized dung) from the Kaiparowits Formation that contain wood may have been produced by ceratopsids. The functions of ceratopsian frills and horns have been debated, and include display, combat, and species recognition. The Kaiparowits Formation dates to the late Campanian age and was deposited on Laramidia, an island continent, when North America was divided at the center by the Western Interior Seaway. This environment was dominated by wetlands and supported a diverse fauna, including dinosaurs such as the chasmosaurine Utahceratops. Based in part on the relationship between Kosmoceratops and other chasmosaurines from around the same time, it has been proposed that Laramidia was divided into dinosaur "provinces" with separate endemic species (this interpretation suggests that Kosmoceratops in the south was most closely related to the geographically separated Vagaceratops in the north), but this has been contested.
Discovery
Since 2000, the Natural History Museum of Utah (UMNH) and the Bureau of Land Management have been conducting paleontological surveys of the Kaiparowits Formation at the Grand Staircase–Escalante National Monument (GSENM) in southern Utah. This national monument was established in 1996 in part for the preservation and study of its fossils, and the surveys there have yielded a wide array of unique dinosaur fossils. Field crews from other institutions have also participated, and the collaborative effort has been called the Kaiparowits Basin Project. Among the discoveries made were three new ceratopsian (horned dinosaur) taxa, one of which was identified from two localities (UMNH Locality VP 890 and 951) discovered by volunteer field crew member Scott Richardson during the field seasons of 2006 and 2007. It was preliminarily referred to as "Kaiparowits new taxon A" and identified as a chasmosaurine ceratopsid in a 2010 book. Prior to this project, the only ceratopsian remains found at the formation were uninformative, isolated teeth. Excavated fossils were transported to the UMNH, where the blocks were prepared by volunteers with pneumatic air scribes and needles and subsequently reassembled. In 2010, the paleontologist Scott D. Sampson and colleagues named the new genus and species Kosmoceratops richardsoni, specimen UMNH VP 17000 (from Locality VP 890) being the holotype. The generic name is derived from the Ancient Greek kosmos, which means "ornamented", and ceratops, which means "horned face". The specific name honors Richardson, who found the holotype and many other fossils at GSENM. The full name can be translated as "ornate horned face of Richardson". The holotype includes a nearly complete adult skull that is missing the predentary bone (the frontmost bone of the lower jaw) and a small part of the left side of the face and neck frill (parts of the jugal, squamosal, and parietal bones), and the snout is bent to the right due to postmortem (after death) distortion. A considerable portion of the axial skeleton (such as vertebrae and ribs) was found associated with the skull, as well as part of the pelvic girdle and a limb. 45 percent of the postcranial skeleton was thought to be preserved, most of which was still under preparation by 2010. Assigned specimens include UMNH VP 16878, a disarticulated skull of a subadult (between juvenile and adult) about half the size of the adult, missing the premaxilla, rostral, and predentary bones, and specimen UMNH VP 21339, a disarticulated subadult or adult. In all, four specimens were reportedly found.
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