Although fossilized dinosaur eggs are generally rare, oviraptorid eggs are relatively well known. Several oviraptorid nests, eggs, and embryos are known, mostly uncovered in the Gobi Desert. Some specimens of "Oviraptor philoceratops", "Citipati osmolskae", "Nemegtomaia" and cf. "Machairasaurus" have been found in brooding positions in association with nests. All of the nesting specimens are situated on top of egg clutches, with their limbs spread symmetrically on each side of the nest, front limbs covering the nest perimeter. This brooding posture is found today only in birds and supports a behavioral link between birds and theropod dinosaurs.