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The Brain of Iguanodon and mantellisaurus: Perspectives on Ornithopod Evolution

par Lauters, Pascaline ;Coudyzer, Walter;Vercauteren, Martine ;Godefroit, Pascal
Editeur scientifique Godefroit, Pascal
Référence Bernissart Dinosaurs and early Cretaceous Terrestrial Ecosystems, Indiana University Press, Bloomington & Indianapolis, page (213-224)
Publication Publié, 2012

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Résumé :

Information on the structure of the brain of the basal iguanodontian dinosaurs Iguanodon bernissartensis and Mantellisaurus atherfieldensis, from the Early Cretaceous of Bernissart, is presented on the basis of computed tomographic scanning and 3D reconstruction of three braincases. The resulting digital cranial endocasts are compared with physical and digital endocasts of other dinosaurs. The orientation of the brain is more horizontal than in lambeosaurine hadrosaurids. The large olfactory tracts indicate that the sense of smell was better developed than in hadrosaurids. The primitive flexures of the midbrain are virtually absent in I. bernissartensis but appear to be better developed in M. atherfieldensis, which might be explained by the smaller body size of the latter. The brain of Iguanodon was relatively larger than in most extant nonavian reptiles, sauropods, and ceratopsians. However, it was apparently smaller than in lambeosaurines and most theropods. The relative size of the cerebrum was low in Iguanodon. In Mantellisaurus, the cerebrum was proportionally larger than in Iguanodon and compares favorably with lambeosaurines. The behavioral repertoire and/or complexity were therefore probably different in the two iguanodontoids from Bernissart, Iguanodon and Mantellisaurus. The enlargement of the cerebrum appeared independently, together with possible capabilities for more complex behaviors, at least two times during the evolution of Iguanodontoidea. © 2012 by Indiana University Press. All rights reserved.