[2][3] Protoceratopsidovum eggs are extremely abundant in the Djadokhta and Barun Goyot Formations.

[4] P. sincerum and P. minimum eggs both have a smooth surface, whereas those of P. fluxuosum have fine ornamentation around the equatorial part.

[3] The eggs of Protoceratopsidovum are classified in the oofamily Prismatoolithidae.

[4] However, more recent research has cast doubt on this: a cladistic analysis in 2008, by Zelenitsky and Therrien, found them to be the eggs of maniraptorans.

Unlike bird eggs (which are laid one at a time), Protoceratopsidovum eggs were laid in pairs because the mother would have two functioning oviducts which would both lay a single egg simultaneously, contrasting with modern birds, which have only one functional oviduct.