To Researchers' Surprise, This Giant Dinosaur Laid Eggs in a Cold Climate

Millions of years ago, giant dinosaurs called titanosaurs laid eggs in surprisingly cold places. A new study looked at fossilized titanosaur eggs from southern Argentina. It shows how these dinosaurs reproduced far from the equator.

Titanosaurs were long-necked, four-legged sauropods. Adults could weigh up to 75 tons. That's much larger than a Tyrannosaurus rex.

Cold Climate Nesting

Darla Zelenitsky, a paleontologist and study co-author, noted that titanosaur bones have been found from Antarctica to Mongolia. She explained that it was not known if they also nested in these colder, higher-latitude areas.

Researchers found 255 egg fragments in Argentina's Chorrillo Formation. These fossils date back about 68 million years. At that time, the area had a climate similar to New York City today.

Zelenitsky and her team studied the eggshells using microscopes and CT scanners. They found the eggshells were very porous. This meant the eggs would dry out and the embryos would die if left in the open.

This suggests titanosaurs incubated their eggs like modern crocodiles. They likely used piles of rotting plants to create heat. Zelenitsky said that burying the eggs in sand, soil, or vegetation would keep them humid enough to survive.

Robert Reisz, a paleontologist not involved in the study, said this research offers new insights into dinosaur reproduction. He highlighted the evidence for mound incubation using decaying plants for heat.

Adapting to Challenges

The research shows how dinosaurs adapted to different environments. It is usually hard for such large animals to find enough resources to survive and reproduce in cold climates. Yet, titanosaurs found a way to nest in these challenging areas.

Researchers do not yet know the exact species of titanosaur that laid these eggs. However, teeth found at the site belonged to colossosaurian titanosaurs. It is possible the eggs and teeth came from the same species.

If these eggs were from colossosaurians, the hatchlings would have needed lots of food to grow to their massive size.

Deep Dive & References

Titanosaur eggshells from the latest Cretaceous of Patagonia reveal a novel reproductive strategy at high paleolatitudes - Royal Society Open Science, 2026