Recent experimental data suggest that oviraptorid dinosaurs, akin to birds, were unable to sufficiently warm their eggs solely through bodily warmth. Instead, they likely supplemented brooding with solar radiation within partially exposed nesting structures.
An artist impression of Huanansaurus ganzhouensis. Image credit: Chuang Zhao.
“Our research demonstrates that variations in oviraptor hatching chronologies stemmed from the positioning of the incubating adult relative to the eggs,” stated Dr. Tzu-Ruei Yang, a paleontologist affiliated with Taiwan’s National Museum of Natural Science.
“Furthermore, we have determined an estimate for the incubation efficacy of oviraptors, which falls considerably short of that observed in contemporary avian species,” commented Chun-Yu Su, a researcher from Washington High School.
Within this investigation, the scientists replicated the nesting habits of Heyuannia huangi, a type of oviraptorid dinosaur that inhabited the geographical region now recognized as China during the Late Cretaceous period, spanning from approximately 70 to 66 million years ago.
With an estimated length of about 1.5 meters and a weight of roughly 20 kilograms, this dinosaur constructed semi-open nests characterized by multiple tiers of eggs.
The body of the incubating oviraptor was meticulously fashioned from polystyrene foam and wood to form the internal framework, complemented by cotton, bubble wrap, and fabric to simulate soft tissues.
Eggs were meticulously crafted from casting resin. In the two nest compositions subjected to the experimental analysis, eggs were arranged in double-layered configurations, mirroring actual oviraptor clutch formations.
“One of the inherent challenges lies in achieving a realistic reconstruction of oviraptor brooding,” Su remarked.
“For instance, their eggs exhibit characteristics unlike those of any extant species, necessitating our development of resin replicas that closely approximated genuine oviraptor eggs to the best of our ability.”
An artist’s depiction of a Late Cretaceous oviraptorosaur, a hadrosaur, and a tyrannosaur in central China. Image credit: Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences.
Upon conducting experiments to ascertain whether clutch attendance by an adult or varying environmental conditions might have influenced hatching sequences, the researchers discovered that in cooler ambient temperatures, with a brooding adult present, the temperatures within the outer perimeter of the eggs exhibited a disparity of up to 6 degrees Celsius. This differential could have led to asynchronous hatching, a phenomenon where eggs within the same nest emerge at staggered intervals.
Under more temperate conditions, the temperature variance in the outer ring of eggs was a more modest 0.6 degrees Celsius, indicating that oviraptors inhabiting warmer climates might have displayed a different pattern of asynchronous hatching, potentially by leveraging the sun as a significant supplementary heat source.
“It is improbable that large dinosaurs directly perched atop their clutches. It is theorized they utilized solar heat or geothermal warmth from the substrate to facilitate egg incubation, much like modern turtles,” posited Dr. Yang.
“Given that oviraptor nests were exposed to the atmosphere, solar irradiance likely played a more pivotal role than subterranean warmth.”
The research team also explored the comparative incubation efficiency of oviraptors versus extant avian species.
The majority of birds engage in thermoregulatory contact incubation, a method where adults establish direct physical contact with the eggs to facilitate heat transfer.
This mode of incubation necessitates three fundamental conditions: the adult bird must be in contact with each egg, serve as the primary heat provider, and maintain all eggs within a narrow thermal range. Oviraptors, however, appear to have fallen short of these requirements.
“Oviraptors likely lacked the capacity to execute thermoregulatory contact incubation in the manner characteristic of contemporary birds,” Su asserted.
“Conversely, these ancient reptiles and the sun may have functioned as collaborative incubators—a less efficient reproductive strategy compared to that exhibited by modern birds.”
“Nevertheless, the amalgamation of parental brooding and an external thermal source—perhaps a behavioral adaptation linked to the evolutionary transition from subterranean to semi-exposed nesting—is not inherently disadvantageous.”
“Modern avian species are not inherently ‘superior’ in hatching their young,” Dr. Yang emphasized.
“Rather, extant birds and oviraptors employ substantially different incubation methodologies, or more precisely, brooding techniques.”
“Neither approach is inherently superior or inferior; the efficacy is contingent upon environmental factors.”
The discoveries have been officially documented and published in the esteemed scientific journal, Frontiers in Ecology and Evolution.
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Chun-Yu Su et al. 2026. Heat transfer in a realistic clutch reveals a lower efficiency in incubation of oviraptorid dinosaurs than of modern birds. Front. Ecol. Evol 14; doi: 10.3389/fevo.2026.1351288
