An unexpected discovery emerged among the dusty layers of a construction site in Ganzhou, southeast China. A fossil egg, smaller than a grape, was uncovered, nestled among five others — perfectly preserved for over 80 million years. At just 29 millimeters in length, it’s the tiniest dinosaur egg ever found.

Paleontologists had seen small eggs before, but nothing like this. This rare find offers a fresh window into the reproductive strategies of theropod dinosaurs from the Late Cretaceous period.

Tiny But Significant

The six eggs were unearthed in 2021 at a construction site near Meilin Township, southeast China. The Ganzhou region has become famous for producing an abundance of dinosaur eggs. Still, this discovery stands out for its size. For comparison, the largest dinosaur eggs belong to Macroelongatoolithus. These were normally about three times as long as they are wide and, reportedly, could be up to 61 cm (2 ft) long.

After three years of painstaking study, the researchers confirmed that the eggs from Ganzhou belong to a non-avian theropod, a group of carnivorous dinosaurs that includes species like Tyrannosaurus rex.

The morphology and microstructure of the eggshells provide clues about the creatures that laid them and how they evolved, according to Lou Fasheng, chief engineer at the Jiangxi Geological Survey and Exploration Institute. However, not much is known about what the dinosaur parents were like. The team named the new species Minioolithus ganzhouensis. The name reflects the egg’s minuscule size and the Ganzhou region where it was discovered.

To analyze these fossils, scientists employed cutting-edge technology, including scanning electron microscopy and electron backscatter diffraction. These tools allowed them to peer inside the eggs without touching the delicate fossils.

What The Little Eggs Can Tell Us

By closely examining the shells, the team discovered unique differences in size, thickness, and overall structure compared to other known fossils. That’s not surprising. Dinosaurs, like today’s reptiles and birds, likely laid eggs that varied widely in size, shape, and texture, depending on species, habitat, and climate.

However, the small eggs may indicate a more diverse set of reproductive strategies than previously thought. The Late Cretaceous period was a time of rapid change, as dinosaurs adapted to shifting landscapes and climates. Some species grew to massive sizes. But others, like the theropods suspected to have laid this egg, may have adapted in smaller, subtler ways.

Next, using advanced techniques like micro-CT scanning, the researchers plan to reconstruct the overall layout of the fossilized nest. This will allow them to study how the eggs were buried and preserved over millions of years, offering clues to the environmental conditions during the Late Cretaceous in the Ganzhou area.

As they dig deeper — both literally and figuratively — the goal is to understand not just the eggs themselves, but the entire ecosystem that allowed these creatures to thrive.