Recent studies reveal that bird-like oviraptorids couldn’t rely solely on body heat for egg incubation. Instead, they utilized both body warmth and sunlight in semi-open nests.
The artist’s impression of Huananzaurus ganjoensis. Image credit: Chuang Zhao.
“Our research indicates that variations in oviraptor hatching strategies are linked to the positioning of adults and eggs,” stated Dr. Tzu-Ruei Yang, a paleontologist at the National Museum of Natural Science, Taiwan.
“We also estimated the hatching efficiency of Oviraptor, which is significantly lower than that of contemporary birds,” added Chun Yu Su, a researcher at Washington High School.
In this investigation, scientists simulated brooding behaviors similar to those of bears. The dinosaur Haeyuannia Fungi, part of the Oviraptoridae family, thrived in present-day China during the late Cretaceous period, approximately 70 to 66 million years ago.
This species is estimated to have reached around 1.5 meters in length and weighed about 20 kilograms, constructing semi-open nests made of multiple egg rings.
During the hatching process, Oviraptor’s model consisted of Styrofoam and wood for structural support, along with cotton, foam paper, and cloth for soft tissue representation.
The eggs were crafted from casting resin, and two clutches were used in the study, organized in double rings to emulate authentic oviraptor nests.
“Reconstructing oviraptor hatching accurately presents significant challenges,” noted Hsu.
“For instance, oviraptor eggs differ substantially from those of modern species, prompting us to create resin eggs that closely mimic the real thing.”
Artist rendition of oviraptorosaurus, hadrosaurus, and tyrannosaurus from the late Cretaceous period of central China. Image credit: Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences.
When exploring how the presence of adult incubators and varying environmental conditions impacted hatching patterns, researchers found that in cooler temperatures where adults participated, egg temperatures in the outer rings could fluctuate by up to 6 degrees Celsius. This resulted in asynchronous hatching, where eggs hatched at different times within a single nest.
In warm environments, the temperature difference between outer ring eggs was only 0.6 degrees Celsius, indicating that oviraptors in warmer climates exhibited distinct asynchronous hatching due to their ability to harness solar heat more effectively.
“It’s unlikely that larger dinosaurs would have remained stationary while incubating eggs. They probably relied on solar heat or warmth from the soil, much like turtles,” Yang explained.
“Given that Oviraptor’s nests are exposed to the air, solar heat played a more crucial role than soil heat in incubation.”
The researchers further compared Oviraptor’s hatching efficiency with that of modern avians.
Typically, contemporary birds use thermoregulatory contact hatching, where the adult directly incubates the eggs, transferring heat.
This method requires three essential conditions: direct contact with all eggs, acting as the primary heat source, and maintaining temperatures within a narrow range—criteria that Oviraptor did not fulfill.
“It’s possible that Oviraptor was incapable of thermoregulatory contact incubation like present-day birds,” Hsu remarked.
“Instead, these dinosaurs might have depended on both adult incubation and sunlight, a strategy that is less efficient than modern avian hatching methods.”
“However, this blend of parental care and ambient heat sources, which could be related to the shift from buried to semi-open nests, isn’t necessarily a disadvantage.”
Dr. Yang clarified, “Modern birds are not inherently superior at incubation.” He explained, “The incubation strategies of oviraptors and modern birds differ significantly, each suited to their environments.”
There’s no categorical ‘good’ or ‘bad’ in these methods; rather, their effectiveness is context-dependent.
The findings were published in Frontiers of Ecology and Evolution.
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Su Chunyu et al. 2026. Realistic heat transfer in clutches reveals that oviraptorid dinosaurs have lower hatching efficiency than modern birds. Front. Ecol. Evol. 14; doi: 10.3389/fevo.2026.1351288
Source: www.sci.news
