Oviraptorosaurs

Oviraptorosaurs are a clade of small to medium-sized theropod dinosaurs within Oviraptorosauria. They lived during the Late Cretaceous, roughly 100 to 66 million years ago, in Asia and North America, with most fossils found in Mongolia and China. The group is divided into two major lineages, Oviraptoridae and Caenagnathidae, which include genera such as Oviraptor, Citipati, and Khaan (oviraptorids), as well as Caenagnathus, Chirostenotes, Anzu, and Gigantoraptor (caenagnathids).

Anatomically, oviraptorosaurs typically had short, beaked snouts and often toothless jaws, though some species bore small teeth. Many possessed tall cranial crests or other ornamentation, and the forelimbs show adaptations for grasping. Fossil evidence indicates they were feathered. Size varied from small to relatively large for theropods, but most were modest in size.

Diet is debated; the beak suggests herbivory or omnivory, perhaps supplemented by small animals or eggs in some taxa. A key aspect of their biology is nesting and parental care: the first described species, Oviraptor philoceratops, was found near eggs, and subsequent discoveries document that oviraptorosaurs brooded nests, illustrating complex reproductive behavior and social care.

Classification and paleobiology: As a group, oviraptorosaurs are part of the broader theropod lineage and are often considered among the closest relatives of birds within Maniraptoriformes. Phylogenetic relationships within Oviraptorosauria are debated, particularly between Oviraptoridae and Caenagnathidae, with several genera sometimes variably placed. They disappeared at the end of the Cretaceous with other non-avian dinosaurs.