Oviraptorid incubation less efficient than modern birds + docodont ulna from Upper Jurassic of Wyoming
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Ben Creisler
Mar 17, 2026, 1:48:55 PM (2 days ago) Mar 17
to DinosaurMa...@googlegroups.com
Ben Creisler
New papers:
Chun-Yu Su, Jun-Yang Liao, Hsiao-Jou Wu, Kuan-Yu Chou, Ching Chen, Ming-Tsang Lee & Tzu-Ruei Yang (2026)
Heat transfer in a realistic clutch reveals a lower efficiency in incubation of oviraptorid dinosaurs than of modern birds
Frontiers in Ecology and Evolution 14:1351288
doi: https://doi.org/10.3389/fevo.2026.1351288
https://www.frontiersin.org/journals/ecology-and-evolution/articles/10.3389/fevo.2026.1351288/full
It has been proposed that some reproductive traits specific to birds, such as thermoregulatory contact incubation (TCI), may also have been present in oviraptorosaurians, as inferred from clutch-associated oviraptorid adults with postures resembling avian brooding behavior. Nevertheless, prerequisites for TCI, such as the incubating adult providing the majority of heat needed for normal embryonic development, have not been evaluated with respect to their body and egg dimensions. To test this, a realistic Heyuannia huangi incubator, oviraptorid clutches, and heat transfer numerical simulations were developed to simulate the brooding behavior of Heyuannia huangi and Nemegtomaia barsboldi. Our results indicate that the incubator could only partially contact the outer-ring eggs of the clutch, leading to a temperature difference between the inner and outer rings and a lower incubation efficiency compared to that of extant birds. Additionally, an outer-ring egg had a considerably higher temperature than the superimposed inner-ring egg when positioned near the incubator’s core, whereas an outer-ring egg had approximately the same temperature as the superimposed inner-ring egg when positioned closer to the incubator’s periphery. If Nemegtomaia barsboldi were to initiate incubation before clutch completion, the temperature distribution could cause the outer-ring egg at the incubator’s core to hatch earlier than the inner-ring egg immediately beneath it, whereas at the periphery the inner-ring egg could hatch earlier than the outer-ring egg immediately above it. However, irrespective of position, the inner-ring egg of Heyuannia huangi may hatch earlier than the outer-ring egg immediately above it. Our findings do not support the TCI hypothesis and instead, they suggest that oviraptorids co-regulated incubation with environmental heat, with the adult stabilizing clutch temperatures, reducing thermal extremes, and influencing patterns of asynchronous hatching.
Free pdf:
Chun-Yu Su, Jun-Yang Liao, Hsiao-Jou Wu, Kuan-Yu Chou, Ching Chen, Ming-Tsang Lee & Tzu-Ruei Yang (2026)
Heat transfer in a realistic clutch reveals a lower efficiency in incubation of oviraptorid dinosaurs than of modern birds
Frontiers in Ecology and Evolution 14:1351288
doi: https://doi.org/10.3389/fevo.2026.1351288
https://www.frontiersin.org/journals/ecology-and-evolution/articles/10.3389/fevo.2026.1351288/full
It has been proposed that some reproductive traits specific to birds, such as thermoregulatory contact incubation (TCI), may also have been present in oviraptorosaurians, as inferred from clutch-associated oviraptorid adults with postures resembling avian brooding behavior. Nevertheless, prerequisites for TCI, such as the incubating adult providing the majority of heat needed for normal embryonic development, have not been evaluated with respect to their body and egg dimensions. To test this, a realistic Heyuannia huangi incubator, oviraptorid clutches, and heat transfer numerical simulations were developed to simulate the brooding behavior of Heyuannia huangi and Nemegtomaia barsboldi. Our results indicate that the incubator could only partially contact the outer-ring eggs of the clutch, leading to a temperature difference between the inner and outer rings and a lower incubation efficiency compared to that of extant birds. Additionally, an outer-ring egg had a considerably higher temperature than the superimposed inner-ring egg when positioned near the incubator’s core, whereas an outer-ring egg had approximately the same temperature as the superimposed inner-ring egg when positioned closer to the incubator’s periphery. If Nemegtomaia barsboldi were to initiate incubation before clutch completion, the temperature distribution could cause the outer-ring egg at the incubator’s core to hatch earlier than the inner-ring egg immediately beneath it, whereas at the periphery the inner-ring egg could hatch earlier than the outer-ring egg immediately above it. However, irrespective of position, the inner-ring egg of Heyuannia huangi may hatch earlier than the outer-ring egg immediately above it. Our findings do not support the TCI hypothesis and instead, they suggest that oviraptorids co-regulated incubation with environmental heat, with the adult stabilizing clutch temperatures, reducing thermal extremes, and influencing patterns of asynchronous hatching.
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Alexander O. Averianov & Hans-Dieter Sues (2026)
A docodont ulna from the Upper Jurassic in North America and its implications for the forelimb morphology in Docodonta (Mammaliaformes)
The Anatomical Record (advance online publication)
doi: https://doi.org/10.1002/ar.70192
https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.70192
An isolated ulna referable to Docodon, from the Upper Jurassic Morrison Formation of Wyoming, resembles the ulna of Borealestes in the presence of a small facet for the radial condyle of the humerus that is confined to the middle of the lateral side of the facet for the ulnar condyle of the humerus and a prominent tubercle on the latter. These taxa and Haldanodon are characterized by the presence of a deep, slit-like lateral fossa for one of the ligaments of the elbow joint. These features are currently only known for Docodonta. However, the ulna of Docodon differs from those of Borealestes and Haldanodon in the lack of an anterior curvature at its proximal end. It shows the most plesiomorphic morphology currently known for docodontans, suggesting that this taxon lacks specialized fossorial or aquatic adaptations.
A docodont ulna from the Upper Jurassic in North America and its implications for the forelimb morphology in Docodonta (Mammaliaformes)
The Anatomical Record (advance online publication)
doi: https://doi.org/10.1002/ar.70192
https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.70192
An isolated ulna referable to Docodon, from the Upper Jurassic Morrison Formation of Wyoming, resembles the ulna of Borealestes in the presence of a small facet for the radial condyle of the humerus that is confined to the middle of the lateral side of the facet for the ulnar condyle of the humerus and a prominent tubercle on the latter. These taxa and Haldanodon are characterized by the presence of a deep, slit-like lateral fossa for one of the ligaments of the elbow joint. These features are currently only known for Docodonta. However, the ulna of Docodon differs from those of Borealestes and Haldanodon in the lack of an anterior curvature at its proximal end. It shows the most plesiomorphic morphology currently known for docodontans, suggesting that this taxon lacks specialized fossorial or aquatic adaptations.
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