A life-sized dinosaur model, resin eggs, and a heat lamp reveal how oviraptors incubated

How do you study the parenting behavior of an animal that went extinct 66 million years ago? If you are Chun-Yu Su, a high school student in Taichung, Taiwan, you build one.

Su, working with Dr. Tzu-Ruei Yang at Taiwan's National Museum of Natural Science, constructed a life-sized model of Heyuannia huangi - an oviraptor roughly 1.5 meters long, weighing about 20 kilograms, that lived between 70 and 66 million years ago in what is now China. The trunk was polystyrene foam and wood for the skeleton, cotton and bubble paper and cloth for soft tissue. The eggs were cast from resin, because no living species produces anything like oviraptor eggs, and arranged in double rings based on real fossilized clutches.

Then they turned on the heat and watched what happened.

The temperature gap in the outer ring

The study, published in Frontiers in Ecology and Evolution, tested whether a brooding adult or environmental conditions had more impact on egg temperatures across a clutch. The results depended heavily on ambient conditions.

In colder temperatures, with a brooding adult attending the clutch, eggs in the outer ring showed temperature differences of up to 6 degrees Celsius. That spread could produce asynchronous hatching - eggs in the same nest hatching at different times, a pattern that affects sibling competition and survival.

In warmer conditions, the outer-ring temperature difference dropped to just 0.6 degrees Celsius. The sun, it turned out, was a powerful equalizer. Oviraptors living in warm climates could rely on solar heating to supplement their body heat, producing more even incubation across the clutch.

"It's unlikely that large dinosaurs sat atop their clutches," Yang explained. "Since oviraptor clutches are open to the air, heat from the sun likely mattered much more than heat from the soil."

Not better, not worse - just different

Modern birds use what biologists call thermoregulatory contact incubation, or TCI. The adult sits directly on every egg, serves as the primary heat source, and keeps all eggs within a narrow temperature range. It is efficient and precise.

Oviraptors could not do this. Their multi-ring egg arrangement physically prevented the adult from contacting every egg. The adult could warm eggs directly beneath its body but could not reach the outer ring. The system required a second heat source - the sun - to compensate.

The researchers estimate that oviraptor incubation was considerably less efficient than modern bird incubation by TCI metrics. But Yang pushed back against framing this as inferiority. "Modern birds aren't 'better' at hatching eggs. Instead, birds living today and oviraptors have a very different way of incubation. Nothing is better or worse. It just depends on the environment."

The combination of adult brooding and ambient solar heat may represent a behavioral adaptation associated with the evolutionary transition from fully buried nests (like those of crocodiles and turtles) to the semi-open nests that eventually became the fully enclosed nests of modern birds.

What a Taiwanese high schooler's model cannot tell us

The study's limitations are inherent to the approach. Today's climate does not resemble the Late Cretaceous, when global temperatures were significantly warmer and atmospheric conditions differed from the present. The model, while carefully constructed, is necessarily an approximation - no one knows the exact thermal properties of oviraptor skin, feathers (if present), or eggs. The resin eggs approximate known oviraptor eggshell properties but are not identical.

The findings are also specific to this one species reconstruction. Other oviraptors varied in size, nest architecture, and likely in incubation strategy. Extrapolating to the broader group requires caution.

Still, the study represents an inventive bridge between physics and paleontology. By building a physical model and running actual heat transfer experiments rather than relying solely on computer simulations, the team captured thermal dynamics that mathematical models might miss.

"There are no dinosaur fossils in Taiwan," Yang noted, "but that does not mean that we cannot do dinosaur studies." Su, who was a high school student when the research was conducted, is proof of that.