Two layers of eggs were originally preserved below the body of the presumed mother. A total of seven distinct eggs were identified in the lower layer where beetle damage was minor, although no embryos or complete eggs were unearthed.
The researchers recovered large fragments of eggs under the skull, left side of the neck, left humerus, left femur, and both feet.
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Long erroneously referred to as egg thieves, oviraptors are now studied for their sophisticated social structure and behavior.
"We know that females couldn't lay more than two eggs at a time. Such large nests, like the one we found, can be explained only as the result of collective layings," Federico Fanti, the paleontologist from the Capellini museum of the Bologna University who found the fossils, told Discovery News.
"The adults possibly cooperated by taking turns at brooding, which occurred for relatively long periods of time. Thus the males could have also sat on eggs," Fanti said.
Contrary to the newly found nest which was located in a desert environment in the late Cretaceous, in the past another individual of Nemegtomaia had been discovered in more recent rocks and in a fluvial habitat.
"It is the sequence of these finds, all in the same area but from different times and environments, that allows us to say that we are dealing with the longest-lived and adaptable oviraptor species ever documented," Fanti said.
Images, from top: Drawing of an oviraptor; egg emerging from the sand; detail of the dinosaur' skull; nest and preserved elements of Nemegtomaia barsboldi. Credit: Photos: Federico Fanti, drawings Marco Auditore