Crystallized dinosaur egg fossils discovered in Shiyan, Central China's Hubei Province on December 20,2023 Photo: Hubei Daily

The Hubei Institute of Geosciences (HIG) announced on Thursday that three very rare crystallized dinosaur egg fossils were discovered on the previous day in Shiyan, Central China's Hubei Province.

Roughly 14-15 centimeters long and around 12 centimeters wide, the eggs all have a flattened oval shape. Experts said that these unique fossils could only have formed under highly specific conditions.

The eggs were discovered at the Hubei Qinglongshan Dinosaur Egg Fossil Group National Nature Reserve, which boasts the world's largest dinosaur egg fossil site in terms of its fossil stock, the HIG said on Thursday.

The revelation occurred during restoration at Site One of the dinosaur egg fossil exhibition hall when a collaborative research team stumbled upon the crystallized eggs nestled within a clutch of 31 eggs. 

The eggshells, with a thickness ranging from 1.31 to 2.4 centimeters, remain preserved in their original buried state.

After carefully scrutinizing a typical egg labeled J2, archaeologists observed a uniform internal crystalline mineral, which was identified as calcite with particle sizes ranging from 0.2 to 0.4 centimeters.

"The discovery holds significant research value for unraveling the process of dinosaur egg laying and reconstructing the ancient environment," noted Zhao Bi, director of the Center for Paleontological Fossil Research at the HIG.

Zhao said that no established theories can explain the formation of these crystallized dinosaur egg fossils, but he suggested that the intact status of the shell indicate these eggs "very likely remained unhatched."

The crystallization of the shell may be attributed to "a highly saturated solution of calcium carbonate permeating through the eggshell pores when the eggs were buried before they became fossils," said Zhao.

Known for their rarity globally, crystallized dinosaur egg fossils were not easily formed due to the stringent environmental and physical-chemical conditions required for their preservation.