Iharkutosuchus, Cretaceous herbivorous crocodile with mammal-like tooth enamel structures + avian postural stability
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Ben Creisler
Feb 4, 2026, 2:27:33 PM (8 days ago) Feb 4
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Ben Creisler
New papers:
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Edina Prondvai, Krisztián Horváth, Stephen WT Price, Olof Gutowski & Andrew Beale (2026)
United by chewing: Hunter-Schreger band-like pattern and wavy enamel in a fossil crocodile suggest functional convergence with mammals and dinosaurs
Proceedings of the Royal Society B: Biological Sciences 293(2064): 20251992
doi: https://doi.org/10.1098/rspb.2025.1992
https://royalsocietypublishing.org/rspb/article/293/2064/20251992/480024/United-by-chewing-Hunter-Schreger-band-like
Tooth enamel of most mammals shows alternating light and dark bands, called Hunter-Schreger bands (HSB), in longitudinal sections caused by decussating bundles of prisms, the unit building blocks of mammalian enamel. HSB are thought to increase resistance to abrasive food and mitigate crack propagation and hence are considered a mammalian adaptation to high-efficiency mastication. Using traditional microscopy techniques as well as X-ray diffraction computed tomography (XRD-CT), here we report for the first time the presence of HSB-like features in the tooth enamel of a non-mammalian amniote, Iharkutosuchus, an extinct herbivorous crocodile with strong heterodonty and a unique chewing mechanism. XRD-CT showed that the enigmatic HSB-like pattern in Iharkutosuchus enamel, which lacks mammal-like decussating prisms, has a purely crystallographic origin. Iharkutosuchus teeth also exhibit wavy enamel, a well-known structure in herbivorous ornithopod dinosaurs with shearing-type mastication. The unexpected finding of both enamel features in this herbivorous crocodile speaks for their role in high-efficiency chewing. However, the profoundly different structural background of mammalian and crocodilian HSB demonstrated here and the phylogenetic distribution of both HSB and wavy enamel indicate nanostructure-scale convergences, highlighting the importance of mastication-related challenges in driving dental evolution of amniotes.
Edina Prondvai, Krisztián Horváth, Stephen WT Price, Olof Gutowski & Andrew Beale (2026)
United by chewing: Hunter-Schreger band-like pattern and wavy enamel in a fossil crocodile suggest functional convergence with mammals and dinosaurs
Proceedings of the Royal Society B: Biological Sciences 293(2064): 20251992
doi: https://doi.org/10.1098/rspb.2025.1992
https://royalsocietypublishing.org/rspb/article/293/2064/20251992/480024/United-by-chewing-Hunter-Schreger-band-like
Tooth enamel of most mammals shows alternating light and dark bands, called Hunter-Schreger bands (HSB), in longitudinal sections caused by decussating bundles of prisms, the unit building blocks of mammalian enamel. HSB are thought to increase resistance to abrasive food and mitigate crack propagation and hence are considered a mammalian adaptation to high-efficiency mastication. Using traditional microscopy techniques as well as X-ray diffraction computed tomography (XRD-CT), here we report for the first time the presence of HSB-like features in the tooth enamel of a non-mammalian amniote, Iharkutosuchus, an extinct herbivorous crocodile with strong heterodonty and a unique chewing mechanism. XRD-CT showed that the enigmatic HSB-like pattern in Iharkutosuchus enamel, which lacks mammal-like decussating prisms, has a purely crystallographic origin. Iharkutosuchus teeth also exhibit wavy enamel, a well-known structure in herbivorous ornithopod dinosaurs with shearing-type mastication. The unexpected finding of both enamel features in this herbivorous crocodile speaks for their role in high-efficiency chewing. However, the profoundly different structural background of mammalian and crocodilian HSB demonstrated here and the phylogenetic distribution of both HSB and wavy enamel indicate nanostructure-scale convergences, highlighting the importance of mastication-related challenges in driving dental evolution of amniotes.
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Roxane Vimbert, Idriss Pelletan, Mathieu Porez, Anick Abourachid & Christine Chevallereau (2026)
The role of tensegrity in the diversity of avian postural stability
Journal of The Royal Society Interface 23(235): 20250631
doi: https://doi.org/10.1098/rsif.2025.0631
https://royalsocietypublishing.org/rsif/article-abstract/23/235/20250631/479914/The-role-of-tensegrity-in-the-diversity-of-avian
Like humans, all birds adopt a strictly bipedal posture. However, unlike humans, birds have such good balance that they can sleep while standing up, which must require minimal energy. This makes them an interesting model for studying bipedalism in robotics. In this study, we examine balance and postural stability via a tensegrity system (assembly in parallel of rigid bodies and cables). To test this hypothesis, we created mathematical models based on anatomical observations of the legs of various birds (zebra finch, little egret, mallard and military macaw) to investigate different configurations. Building on a previous model, we demonstrate that tensegrity systems can achieve passive stability under simplified loading. Here, we aim to establish whether this model can be generalized, to determine stability, and to identify the impact of certain kinematic, dynamic and material parameters. Our results enabled us to identify the parameters that allow the model to be generalized. We determined that adding two cables corresponding to tendinous and muscular sets generalizes the model to a varied range of configurations and exploits the rear part of the foot when present. These findings offer new insights into avian bipedalism and could inspire the design of bipedal robots with passive stability for greater autonomy.
The role of tensegrity in the diversity of avian postural stability
Journal of The Royal Society Interface 23(235): 20250631
doi: https://doi.org/10.1098/rsif.2025.0631
https://royalsocietypublishing.org/rsif/article-abstract/23/235/20250631/479914/The-role-of-tensegrity-in-the-diversity-of-avian
Like humans, all birds adopt a strictly bipedal posture. However, unlike humans, birds have such good balance that they can sleep while standing up, which must require minimal energy. This makes them an interesting model for studying bipedalism in robotics. In this study, we examine balance and postural stability via a tensegrity system (assembly in parallel of rigid bodies and cables). To test this hypothesis, we created mathematical models based on anatomical observations of the legs of various birds (zebra finch, little egret, mallard and military macaw) to investigate different configurations. Building on a previous model, we demonstrate that tensegrity systems can achieve passive stability under simplified loading. Here, we aim to establish whether this model can be generalized, to determine stability, and to identify the impact of certain kinematic, dynamic and material parameters. Our results enabled us to identify the parameters that allow the model to be generalized. We determined that adding two cables corresponding to tendinous and muscular sets generalizes the model to a varied range of configurations and exploits the rear part of the foot when present. These findings offer new insights into avian bipedalism and could inspire the design of bipedal robots with passive stability for greater autonomy.
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