How did dinosaurs hatch their eggs?
Scientists have long debated whether bird-like dinosaurs used body heat like modern birds or relied more on environmental heat, like reptiles.
A new study from researchers in Taiwan offers fresh clues by recreating how one group of dinosaurs, called oviraptors, may have incubated their eggs—and the results suggest they were less efficient than today’s birds.
Oviraptors were feathered, bird-like dinosaurs that lived around 70 million years ago in what is now China.
Although they shared some similarities with birds, they could not fly.
Their nests were unusual, made up of rings of eggs arranged in circular patterns. This structure raised questions about how they kept all their eggs warm enough to hatch.
To investigate, the research team built a life-sized model of an oviraptor, based on a species called Heyuannia huangi.
The model included a reconstructed body made from foam, wood, and fabric, designed to mimic the shape and heat of a real animal. They also created artificial eggs using resin, carefully arranging them in double-ring patterns based on fossil evidence.
The scientists then ran experiments to see how heat was distributed across the eggs under different conditions.
In cooler environments, where the adult dinosaur was assumed to be sitting over the nest, they found that eggs in the outer ring could differ in temperature by as much as 6°C. This uneven heating would likely cause eggs to hatch at different times, a process known as asynchronous hatching.
In warmer conditions, however, the temperature difference between eggs dropped to just 0.6°C. This suggests that sunlight may have played an important role in helping to warm the eggs more evenly. Because oviraptor nests were open to the air, heat from the sun likely contributed significantly to incubation.
The study also compared oviraptor incubation with that of modern birds. Today’s birds use a method called contact incubation, where the adult sits directly on the eggs and keeps them at a stable temperature. This method requires the adult to touch all the eggs and act as the main heat source.
Oviraptors, however, likely could not do this effectively. Their circular nest design meant that the adult could not fully cover all the eggs at once. As a result, they may have relied on a combination of body heat and environmental warmth, such as sunlight, to incubate their eggs.
This mixed approach was less precise than the system used by modern birds, but researchers say it does not mean it was worse. Instead, it reflects a different strategy shaped by the environment and the evolutionary stage of these dinosaurs.
The study also highlights how creative methods—such as building physical models and running heat simulations—can help scientists better understand ancient life.
While there are still uncertainties, especially since today’s climate differs from that of the dinosaur era, the research provides valuable insight into how these fascinating creatures reproduced millions of years ago.
