Qing He et al/Journal of Paleontology 

Paleontologists have discovered cannonball-size dinosaur eggs filled with crystals in the Qianshan Basin in East China's Anhui province, Live Science reported.

The fossilized, spherical eggs belong to a previously unknown dinosaur species and were found packed with calcite crystals. Though three eggs were dug up from the basin's soil, only two remain. The researchers who made the discovery said that the third was "lost and still in the process of collection".

The remaining eggs have been classified with the name Shixingoolithus qianshanensis, making them newly described oospecies.

Oospecies, oogenera, and oofamilies are the taxonomic names for dinosaurs known only from their eggs.

The results were published on August 25 in the Journal of Paleontology.

The researchers described the eggs as "nearly spheroid" and cannonball-sized, with a length of 4.1 to 5.4 inches (105 to 137 millimeters) and a width of 3.9 to 5.3 inches (99 to 134 mm). The preserved two dinosaur eggs contain an incomplete one and a complete one, named QS-01 and QS-02 based on the sequence of discovery.

The incomplete dinosaur egg (QS-01) revealed its inner surface, which was "filled with clusters of calcite crystals". According to the study, six eggshell fragments with fewer calcite crystals from QS-01 and QS-02 were collected and the eggshell thickness was measured several times with a caliper. The loose sediments that had collected on the outer surface of the eggshells were removed with small needles and then cleaned in an ultrasonic bath at the Geological Laboratory of Anhui University.

The study authors explain that calcite, a carbonate mineral, is commonly found in the eggs of birds and dinosaurs. Calcite crystals usually form when calcium carbonate separates from the eggshell structure and gets deposited on its internal surface in the form of slowly growing crystals.

Qing He et al/Journal of Paleontology 

Live Science mentions a previous study published in 2014 in the journal Cretaceous Research that suggests the possibility of the previously discovered Shixingoolithus eggs of a different species belonging to an ornithopod — a group of duck-billed, herbivorous, and mostly bipedal dinosaurs that grew to up to 30 feet (nine meters) long.

Ornithopods lived from the latter part of the Triassic period (251.9 million to 201.3 million years ago) to the late Cretaceous period (145 million to 66 million years ago) — after which they and all the other non-avian dinosaurs were wiped out by the impact and the aftermath of the Chicxulub asteroid, which slammed into the Yucatán peninsula.

After that "cataclysmic" collision, massive amounts of sulfur were propelled into the stratosphere. Now, these sulfur gases blocked out the soon, cooling Earth, likely for centuries, and producing dangerous acid rain. This altered the chemistry of the oceans for tens of thousands of years, leading to the extinction of around 75 percent of Earth's plant and animal species, including the aforementioned ornithopods.

East China then experienced volcanic eruptions that deposited vast amounts of sediment, making the region a treasure mine for fossil hunters.

National Geographic reported that more than 60 species of plants, nearly 90 species of vertebrates, and around 300 species of invertebrates have been identified in China's northwestern Liaoning province alone. According to the researchers, such conditions are excellent for preserving dinosaur eggs.

"Dinosaur eggs in the Upper Cretaceous of China are characterized by prodigious quantities, abundant types, and wide distribution. Approximately 16 oofamilies and 35 oogenera have been reported in China and most fossils come from the Xixia Basin of Henan Province, the Nanxiong Basin of Guangdong Province, the Ganzhou Basin of Jiangxi Province, the Tiantai Basin of Zhejiang Province, and the Jiaolai Basin of Shandong Province," they said in the study.

Here we describe two newly discovered dinosaur eggs from the Upper Cretaceous Chishan Formation in the Qianshan Basin, Anhui Province, East China. These dinosaur eggs can be assigned to a new oospecies of Stalicoolithidae, Shixingoolithus qianshanensis, based on the following combined features: the larger size of eggs, the uniform eggshell microstructure in the radial section, the smaller height and the larger density of radial microstructures at the inner surface of the eggshell. Radial sections of S. qianshanensis show closely arranged columnar eggshell units forming relatively uniform and dense microstructure; some secondary eggshell units and numerous sub-circular radial microstructures appear separately in the middle and inner parts of the tangential sections, respectively. The discovery of S. qianshanensis provides new fossil types of Stalicoolithidae and represents the first dinosaur relative record in the Qianshan Basin, which offer accurate paleontological evidence of Late Cretaceous–Early Paleocene stratigraphic classification in the Qianshan Basin, Anhui Province.