Originally, oviraptorids were thought to be specialized egg raiders, based on a Mongolian find showing "Oviraptor" on top of a nest erroneously attributed to the ceratopsian dinosaur "Protoceratops". However, discoveries in the 1990s, including "Citipati" specimens clearly brooding (rather than preying on) the same types of nests, and a "Citipati" embryo inside the same type of egg preserved in these nests, showed that the "specialized egg thief" idea was incorrect. Still, some scientists have suggested that oviraptorids may have fed on shelled food items like eggs or shellfish. However, animals specialized for eating shelled food typically have broad, crushing beaks or teeth. In contrast, the jaws of oviraptorids had thin, sharp edges probably supporting shearing beaks, ill-suited for cracking shells. Among other known animals, the beaks of oviraptorids most closely resemble those of herbivorous dicynodont synapsids, which are usually considered herbivorous. Their beaks also share similarities with the beaks of herbivorous parrots and tortoises.