3D Finite Element Analysis of a Capitosaurian Skull (Temnospondyli) from the Triassic of Madagascar


The work “3D Finite Element Analysis of a Capitosaurian Skull (Temnospondyli) from the Triassic of Madagascar” by Josep Fortuny (Institut Català de Paleontologia) , Jordi Marcé-Nogué (Universitat Politècnica de Catalunya) and Sébastie Steyer (Muséum national d’Histoire naturelle, Paris, France) has been presented in a poster format in the Society of Vertebrate Palaeontology 72 Annual Meeting.

Capitosaurians are Triassic temnospondyl amphibians characterized by large, parabolic and heavy skulls as well as extensive pectoral girdles. They exhibit aquatic features such coastal ecosystems. They are usually compared with crocodilians because they seem to capture prey by direct bite using active swimming, but their precise feeding ecology remains poorly known. To start to solve this problem, we analyzed the skull of Edingerella madagascariensis, a basal capitosaurian from the marine Olenekian (Early Triassic) of Madagascar, using 3D Finite Element Analysis (FEA). A CT scan of an exquisite adult skull resulted in a 3D model. We analyzed this model under three different biting simulations (bilateral, unilateral and lateral cases). Previous works testing 2D FEA on capitosaurs suggested that the skull of E. madagascariensis is one of the weakest among capitosaurians during feeding. Our 3D analyses reveals that the skull roof displays an important amount of stress near the circumborbital region and the otic notch area during biting. In the palate, the stress is considerable on the parasphenoid and pterygoid whereas the cultriform process shows low stress during biting. The stress also increases in the vomerine plate during unilateral biting. These results are interesting because they are similar with those obtained from archosaurian skulls in which the secondary palate provides lower stress values. This stress is especially important during unilateral bite. We therefore interpret that this unilateral type of bite was not optimal for taxa without secondary palates, such as temnospondyls.

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