Hypselosaurus eggs

Dinosaurs, much like their modern relatives, birds, laid eggs as a fundamental part of their life cycle. Some dinosaurs built nests on the ground, while others, similar to certain reptiles today, are believed to have buried their eggs.

The museum houses an exceptionally well-preserved fossilized nest of eggs from the Hypselosaurus, a long-necked dinosaur (sauropod) that roamed the Earth during the late Cretaceous period, around 70 million years ago. Eggs from a Hypselosaurus have been discovered as far back as 1846, initially mistaken for eggs from a large bird. Remarkably, these eggs, are believed to have been laid by the mother as she was moving forward, not in a nest. Preserved in the exact position they were left 70 million years ago, these eggs provide a rare glimpse into the ancient past.

Upon hatching, the Hypselosaurus was no larger than a rabbit, reaching its full size within an astonishing 10-15 years. At maturity, it grew to an impressive 12 meters in length, stood 4.5 meters tall, and weighed around 10,000 kilograms. The gallery showcases images depicting the likely appearance of the Hypselosaurus. Hypselosaurus was one of the last sauropods in Europe, feeding on plants and widely distributed in the area that now comprises northern Spain and France. This nest was found in Provence, France, in 2023.

Results From the Scanning

The fossilized eggs, 100% intact, have sparked curiosity about their contents. In October 2023, the Museum of Evolution took a significant step towards further discovery, as the eggs were delicately transported from the museum to Aarhus University’s Department of Clinical Medicine for thorough scanning using advanced medical CT systems.

Each of the 13 eggs were individually scanned, revealing a thrilling discovery—more than half of the eggs had hatched before fossilization, giving life to newborn dinosaurs.

A Closer Look at the Shell

Scientists found shattered pieces at the bottom of many shells, concluding that nine of the 13 eggs had finished the hatching process. Further examination, however, revealed that some eggs did not exhibit clear signs of hatching and, instead, presented a fascinating mystery.

Four compressed and broken, yet unhatched eggs contained hyperintense structures. While these structures are not remnants of unborn dinosaurs, their origin remains unknown. The only way to delve deeper into this mystery would be to crack open one of the eggs—an action that, out of respect for the past, will not be undertaken.

The Museum of Evolution considers having fossilized evidence of the early stages of a dinosaur's life cycle as an integral part of being able to piece together the dinosaur era story.