What is "gobioolithus"

Gobioolithus is an oogenus of fossil bird egg native to Mongolia. They are small, smooth-shelled, and elongated eggs that were first discovered in the 1960s and early 70s during a series of fossil-hunting expeditions in the Gobi desert. Two oospecies have been described: Gobioolithus minor and G. major. The eggs were probably laid in colonial nesting sites on the banks of rivers and lakes.

G. minor is unusual because it frequently is found with embryonic skeletons of the enantiornithine bird Gobipipus. Interestingly, these embryos have very well-developed wings, which suggest they would be able to fly very soon after hatching, unlike most modern birds.