Scientists Built a Life-Size Dinosaur Nest and the Results Were Surprising

How exactly did oviraptors, bird-like but flightless dinosaurs, hatch their eggs? Scientists have long debated whether these dinosaurs relied mainly on heat from the environment, similar to crocodiles and turtles, or used body warmth from a brooding adult like modern birds. A new study published today in Frontiers in Ecology and Evolution takes a closer look at this mystery.

Researchers in Taiwan analyzed oviraptor brooding behavior and egg hatching patterns. They also ran heat transfer simulations on oviraptor egg clutches and compared the results with incubation efficiency in modern birds. To test their ideas, the team created a life-sized experimental setup using a model oviraptor and artificial eggs designed to mimic the real ones.

“We show the difference in oviraptor hatching patterns was induced by the relative position of the incubating adult to the eggs,” said senior author Dr. Tzu-Ruei Yang, an associate curator of vertebrate paleontology at Taiwan’s National Museum of Natural Science.

“Moreover, we obtained an estimate of the incubation efficiency of oviraptors, which is much lower than that of modern birds,” added first author Chun-Yu Su, who attended Washington High School in Taichung when the research was conducted.

Recreating a Dinosaur Nest
The team based their reconstruction on Heyuannia huangi, a species of oviraptor that lived roughly 70 to 66 million years ago in what is now China. This dinosaur was estimated to be about 1.5 meters long and weigh around 20kg. It built semi-open nests containing multiple rings of eggs.

To recreate the brooding dinosaur, researchers constructed a trunk using polystyrene foam and wood for the internal frame. Cotton, bubble paper, and cloth were added to simulate soft tissues. The eggs themselves were produced from casting resin.

Two experimental clutches were arranged in double rings, reflecting the structure seen in fossilized oviraptor nests. This unusual layout meant that not every egg could come into direct contact with the brooding adult.

“Part of the difficulty lies in reconstructing oviraptor incubation realistically,” said Su. “For example, their eggs are unlike those of any living species, so we invented the resin eggs to approximate real oviraptor eggs as best as we could.”

Temperature Differences in Dinosaur Egg Clutches
The experiments explored how the presence of a brooding adult and different environmental temperatures could influence egg warming and hatching patterns.

In colder conditions with an adult attending the nest, eggs located in the outer ring showed temperature differences of up to 6°C. Such variation could cause asynchronous hatching, where eggs from the same clutch emerge at different times.

Under warmer conditions, the outer ring eggs showed only about a 0.6°C temperature difference. This suggests that oviraptors living in warmer climates may have experienced different hatching patterns because sunlight could serve as an additional heat source.