Neuroanatomía comparada de tres ejemplares de ornitópodo del Cretácico Inferior de Morella en el 85th Annual Meeting de la SVP

En el encuentro de la Society of Vertebrate Paleontology de este 2025 en Birmingham (Reino Unido), se ha presentado la reconstrucción neuroanatómica de Iguanodon bernissartensis y dos ornitópodos estiracosternos no hadrosauroideos de la Formación Arcillas de Morella realizada mediante técnicas 3D. Los nuevos neurocráneos muestran gran variabilidad tanto en la morfología de la cavidad encefálica, la posición de nervios craneales y del oído interno. Estas diferencias sugieren que los especímenes de Morella posiblemente podrían haber tenido diferentes capacidades sensoriales y/o cognitivas. A nivel evolutivo se ha podido establecer una clara tendencia a la reducción del oído, a la pérdida del flocculus y la desaparición de las flexiones craneales en iguanodontidos basales. El resumen es el siguiente:

The upper Barremian beds of Morella have yielded multiple partial skeletons of non hadrosauroid styracosternan ornithopods. These fossils have been identified so far as Iguanodon bernissartensis and a new form exclusive to the formation, Morelladon beltrani. In recent years, paleontological surveillance of clay-mining activities has brought up several new partial skeletons, three of them with partial skulls, including well-preserved braincases. To evaluate potential neuroanatomical differences, the braincases were scanned, which enabled access to new endocranial anatomical information. A 3D model was generated to virtually reconstruct the morphology of the braincase and its internal cavities. Specimen 1, referrable to Iguanodon bernissartensis, has a complete and well preserved braincase, allowing to reconstruct a detailed endocast. The olfactory bulbs and tracts, cerebral hemispheres, pituitary body, dural peak, cerebellum and the medulla oblongata were identified and reconstructed. Also, the inner ear and almost all cranial nerves and the internal carotid artery were also preserved. Two additional specimens don’t have a taxonomic identification yet beyond non hadrosauroid Styracosterna. Specimen 2 didn’t preserve frontals, and parietals and the orbitosphenoid are incomplete. The endocast is complete but missing the anterior part of the forebrain. The posterior half of the cerebral hemispheres is preserved as are the pituitary and the internal carotid artery. The mid- and forebrain and all structures associated with them are well preserved as well. Specimen 3 preserves the complete encephalic mass, most of the inner ears, most cranial nerves and main blood vessels like the internal carotid artery or the caudal middle cerebral vein.

These specimens display notable differences among them in the general shape of the encephalic mass, with specimen 1 almost lacking cephalic and pontine flexures, specimen 3 having a very pronounced dural peak (next to both other Morella specimens and also with other ornithopods) and all three of them having different relative positions of anterior cranial nerves relative to the pituitary and differences in morphology and relative size of the inner ear semicircular canals.

These neuroanatomical differences suggest the specimens from Morella possibly belonged to different taxa and that they might have had noticeable sensory or cognitive differences that could be linked to anatomical or ecological variability of each specimen.

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Más información:

• Referencia: Ciudad Real Ballestero, M., Escaso, F., Gasulla, J. M., Ortega, F. (2025). Comparative neuroanatomy of three ornithopod individuals from the Lower Cretaceous of Morella (Castellon, Spain). In Hunter, J., Turner, N., Vlachos, E., Whatley, R. (Eds.) 85th Annual Meeting of SVP. Abstract book. Birmingham, 183-184.