[4][8] Macroelongatoolithus specimens are extremely variable in size, shape, and microstructure, even in eggs laid by a single individual.

[7] Macroelongatoolithus eggs closely resemble those of oviraptorids (Elongatoolithidae),[10] which are largely known for their brooding adult-nest associations, embryonic remains, and unique nests.

[4] In 2017 the caenagnathid Beibeilong was described, based on an embryonic specimen (named "Baby Louie") associated with 6 to 8 Macroelongatoolithus eggs and partial nest.

The discovery of Beibeilong further concludes that the oogenus Macroelongatoolithus was laid by large oviraptorosaurs, in this case caenagnathids.

Their results showed that eggshell porosity indicates that the eggs of almost certainly all oviraptorosaurs were exposed in the nest without an external covering.

Tanaka and colleagues pointed out that this adaption was beneficial to avoid egg-crushing and could have allowed some body-contact during incubation in these giant oviraptorosaurs.

[11] Macroelongatoolithus eggs have been found in the United States, China, and South Korea, ranging in age from Early Cretaceous to Maastrichtian.

[16][17] The presence of Macroelongatoolithus in the United States indicates that there was likely a giant oviraptorosaur present during the Late Cretaceous in North America.

Also, the fact that they have been found in both Asia and North America is evidence of an Albian-Cenomanian interchange of fauna between the two continents.