The presence of tiny "Byronosaurus" skulls in an oviraptorid nest was considered an enigma. "Heyuannia" is a medium-sized oviraptorid. The presence of tiny troodontids in an oviraptorid nest is an enigma. Rinchenia is a genus of Mongolian oviraptorid dinosaur from the late Cretaceous Period. Macroelongatoolithus is an oogenus of large, fossil theropod eggs (probably representing a giant oviraptorid). Gobiraptor is a genus of oviraptorid maniraptoran dinosaur from the Maastrichtian-age Nemegt Formation of Mongolia. "Macroolithus" eggs have been found containing oviraptorid dinosaur embryos resembling "Heyuannia". Norell "et al.", who recognized the embryo as oviraptorid, assigned it to the genus "Citipati". The oviraptorid diet is disputed, with plants and molluscs having been suggested. Although fossilized dinosaur eggs are generally rare, oviraptorid eggs are relatively well known. "Wulatelong" is an oviraptorid dinosaur, the sister taxon of "Banji". Several oviraptorid nests, eggs, and embryos are known, mostly uncovered in the Gobi Desert.