Scientists in Taiwan built a full-size model of a dinosaur nest. They wanted to answer an old question. How did oviraptors keep their eggs warm? Oviraptors were dinosaurs with feathers. They could not fly. They lived about 70 million years ago.

The team built a model dinosaur and fake eggs. They made the eggs from resin. They put the eggs in two rings, just like real fossil nests. Then they tested how heat moved through the nest.

The results were interesting. The mother dinosaur could not touch every egg. Only eggs near her body got warm from her. Other eggs stayed cooler. The sun also helped warm the nest. Because of this, some eggs probably hatched before others. This is different from birds today. Most birds warm every egg the same way. The study appeared in a science journal called Frontiers in Ecology and Evolution.

Researchers in Taiwan have built a life-size model of an oviraptor nest to solve a question that has puzzled paleontologists for decades: how did these bird-like, flightless dinosaurs incubate their eggs? The team focused on Heyuannia huangi, a species that lived between 70 and 66 million years ago and weighed around 20 kilograms.

To recreate the nest, the scientists built a model adult out of foam, wood, cotton, and cloth, along with resin eggs arranged in double rings, matching the pattern found in fossilized clutches. Using heat-transfer simulations, they discovered that the adult could not make direct contact with every egg, unlike most modern birds, which use body heat to warm their entire clutch evenly.

As a result, eggs closer to the parent's body stayed noticeably warmer than those farther away, sometimes by as much as 6 degrees Celsius. This uneven heating suggests that oviraptor eggs likely hatched at different times rather than all at once, relying on a combination of body warmth and sunlight, a less efficient method than the incubation strategies used by birds today.

For decades, paleontologists have debated how oviraptors, flightless dinosaurs closely related to birds, incubated their eggs: did they rely on body heat like modern birds, or on environmental warmth like reptiles? A team of researchers in Taiwan has now offered compelling evidence by constructing a life-size physical replica of an oviraptor nest, combining it with heat-transfer simulations to settle the question.

The study reconstructed Heyuannia huangi, a roughly 1.5-meter-long oviraptor that lived in what is now China between 70 and 66 million years ago. Using polystyrene foam, wood, and cloth to build a model adult, and casting resin to fabricate eggs, the researchers arranged two clutches in double rings, mirroring the distinctive pattern preserved in fossilized nests.

The experiments revealed that, unlike most modern birds, which rely on thermoregulatory contact incubation, oviraptors could not maintain direct contact with every egg simultaneously. Consequently, eggs positioned closer to the parent's body retained significantly more heat than peripheral ones, sometimes differing by up to six degrees Celsius under cooler conditions, though this gap narrowed considerably in warmer simulations. This asymmetry suggests that oviraptor eggs hatched asynchronously rather than in unison, implying a hybrid incubation strategy in which sunlight complemented the adult's limited body heat. The findings, published in the journal Frontiers in Ecology and Evolution, indicate that oviraptor incubation was considerably less efficient than that observed in contemporary avian species.