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Link to original content: http://pubmed.ncbi.nlm.nih.gov/38600295/
Cranial functional specialisation for strength precedes morphological evolution in Oviraptorosauria - PubMed Skip to main page content
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. 2024 Apr 10;7(1):436.
doi: 10.1038/s42003-024-06137-1.

Cranial functional specialisation for strength precedes morphological evolution in Oviraptorosauria

Luke E Meade  1 , Michael Pittman  2 , Amy Balanoff  3 , Stephan Lautenschlager  4
Affiliations

Cranial functional specialisation for strength precedes morphological evolution in Oviraptorosauria

Luke E Meade et al. Commun Biol. .

Abstract

Oviraptorosaurians were a theropod dinosaur group that reached high diversity in the Late Cretaceous. Within oviraptorosaurians, the later diverging oviraptorids evolved distinctive crania which were extensively pneumatised, short and tall, and had a robust toothless beak, interpreted as providing a powerful bite for their herbivorous to omnivorous diet. The present study explores the ability of oviraptorid crania to resist large mechanical stresses compared with other theropods and where this adaptation originated within oviraptorosaurians. Digital 3D cranial models were constructed for the earliest diverging oviraptorosaurian, Incisivosaurus gauthieri, and three oviraptorids, Citipati osmolskae, Conchoraptor gracilis, and Khaan mckennai. Finite element analyses indicate oviraptorosaurian crania were stronger than those of other herbivorous theropods (Erlikosaurus and Ornithomimus) and were more comparable to the large, carnivorous Allosaurus. The cranial biomechanics of Incisivosaurus align with oviraptorids, indicating an early establishment of distinctive strengthened cranial biomechanics in Oviraptorosauria, even before the highly modified oviraptorid cranial morphology. Bite modelling, using estimated muscle forces, suggests oviraptorid crania may have functioned closer to structural safety limits. Low mechanical stresses around the beaks of oviraptorids suggest a convergently evolved, functionally distinct rhamphotheca, serving as a cropping/feeding tool rather than for stress reduction, when compared with other herbivorous theropods.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Fig. 1
Fig. 1. Von Mises stress distribution from comparative bending test using scaled loading.
Von Mises stress (MPa) contour plots from FEA modelling a comparative bending test on cranial models of oviraptorid oviraptorosaurians Conchoraptor (a), Khaan (b), Citipati (c), early diverging oviraptorosaurian Incisivosaurus (d), and non-oviraptorosaurian theropods Allosaurus (e), Erlikosaurus (f), and Ornithomimus (g). Results from loads applied bilaterally for three different locations on the palate and unilaterally at the mid-palate. Applied forces scaled so ratio of cranial surface area:force applied was identical in all. Scale bars on the right are 50 mm.
Fig. 2
Fig. 2. Von Mises stress data from comparative bending test using scaled loading.
Mean values and whiskers showing first quartile, median, and third quartile of von Mises stress (MPa) from FEA of bilaterally and unilaterally applied palatal bending forces (scaled to relative surface area) at three positions on the palate of cranial models of oviraptorosaurians Conchoraptor, Khaan, Citipati, and Incisivosaurus, along with Allosaurus, Erlikosaurus, and Ornithomimus. Ant = anterior, Mid = mid-palate, Pos = posterior.
Fig. 3
Fig. 3. Von mises stress distribution from biting test using estimated muscle force vectors.
Von Mises stress (MPa) contour plots from FEA modelling different bite positions in cranial models of oviraptorid oviraptorosaurians Conchoraptor (a), Khaan (b), Citipati (c), early diverging oviraptorosaurian Incisivosaurus (d), and non-oviraptorosaurian theropods Allosaurus (e), Erlikosaurus (f), and Ornithomimus (g). Force vectors were estimated from volumetric adductor muscle reconstruction and bite points modelled with bilateral constraints for three different locations on the palate and unilaterally at the mid-palate. Scale bars on the right are 50 mm.
Fig. 4
Fig. 4. Von Mises stress data from biting test using estimated muscle force vectors.
Mean values and whiskers showing first quartile, median, and third quartile of von Mises stress (MPa) from FEA using estimated adductor muscle forces modelling biting at three positions on the palate of cranial models of oviraptorosaurians Conchoraptor, Khaan, Citipati, and Incisivosaurus, along with Allosaurus, Erlikosaurus, and Ornithomimus. Ant = anterior, Mid = mid-palate, Pos = posterior.
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