Paleoneuroanatomy of the European lambeosaurine dinosaur Arenysaurus ardevoli

The neuroanatomy of hadrosaurid dinosaurs is well known from North America and Asia. In Europe only a few cranial remains have been recovered that include the braincase. Arenysaurus is the first European endocast for which the paleoneuroanatomy has been studied. The resulting data have enabled us to draw ontogenetic, phylogenetic and functional inferences. Arenysaurus preserves the endocast and the inner ear. This cranial material was CT scanned, and a 3D-model was generated. The endocast morphology supports a general pattern for hadrosaurids with some characters that distinguish it to a subfamily level, such as a brain cavity that is anteroposteriorly shorter or the angle of the major axis of the cerebral hemisphere to the horizontal in lambeosaurines. Both these characters are present in the endocast of Arenysaurus. Osteological features indicate an adult ontogenetic stage, while some paleoneuroanatomical features are indicative of a subadult ontogenetic stage. It is hypothesized that the presence of puzzling mixture of characters that suggest different ontogenetic stages for this specimen may reflect some degree of dwarfism in Arenysaurus. Regarding the inner ear, its structure shows differences from the ornithopod clade with respect to the height of the semicircular canals. These differences could lead to a decrease in the compensatory movements of eyes and head, with important implications for the paleobiology and behavior of hadrosaurid taxa such as Edmontosaurus, Parasaurolophus and Arenysaurus. The endocranial morphology of European hadrosaurids sheds new light on the evolution of this group and may reflect the conditions in the archipelago where these animals lived during the Late CretaceousPeer ReviewedPostprint (published version

Kinematic model of savannah monitor locomotion

Postprint (published version

Quasi-homothetic transformation for comparing the mechanical performance of planar models in biological research

The potential of Finite Element Analysis (FEA) as an analytical technique in biological research has been widely highlighted in recent years. In spite of its great power, only in the best of circumstances one can compare the behaviour of models that differ in size and shape. Here, a new and easy procedure to scale FE models of plane elasticity is presented for several species of extant bovids that significantly differ in size and morphology. The method is based on the modification of the values of the forces applied by taking into account the particularities of the elasticity plane models (plane strain and plane stress equations) using quasi-homothetic transformations. This approach is shown to be extremely useful when exploring the effect of the shape in front of the strength and the stiffness of vertebrate bone structures. Thus, the quasi-homothetic concept is a new and interesting proposal to be used in plane elasticity models of biological, and specifically of vertebrate, structures which can be modelled as two-dimensional finite element models.Peer ReviewedPostprint (published version

Finite element analysis of the Cingulata jaw: an ecomorphological approach to Armadillo's diets

Finite element analyses (FEA) were applied to assess the lower jaw biomechanics of cingulate xenarthrans: 14 species of armadillos as well as one Pleistocene pampathere (11 extant taxa and the extinct forms Vassallia, Eutatus and Macroeuphractus). The principal goal of this work is to comparatively assess the biomechanical capabilities of the mandible based on FEA and to relate the obtained stress patterns with diet preferences and variability, in extant and extinct species through an ecomorphology approach. The results of FEA showed that omnivorous species have stronger mandibles than insectivorous species. Moreover, this latter group of species showed high variability, including some similar biomechanical features of the insectivorous Tolypeutes matacus and Chlamyphorus truncatus to those of omnivorous species, in agreement with reported diets that include items other than insects. It remains unclear the reasons behind the stronger than expected lower jaw of Dasypus kappleri. On the other hand, the very strong mandible of the fossil taxon Vassallia maxima agrees well with the proposed herbivorous diet. Moreover, Eutatus seguini yielded a stress pattern similar to Vassalia in the posterior part of the lower jaw, but resembling that of the stoutly built Macroeuphractus outesi in the anterior part. The results highlight the need for more detailed studies on the natural history of extant armadillos. FEA proved a powerful tool for biomechanical studies in a comparative framework.Peer ReviewedPostprint (published version

First xiphosuran traceway in the middle Muschelkalk facies (Middle Triassic) of the Catalan Basin (NE Iberian Peninsula)

In the last decade, the first ichnoassamblages from the middle Muschelkalk facies (upper Anisian-middle Ladinian) of the Catalan Basin (NE Iberian Peninsula) have been discovered. Herein, the first xiphosuran trace fossils are described from the locality of Penya Rubí, a newly discovered ichnosite from the Catalan Basin. The finding opens a window into peri-Tethys ecosystems with coastal influence. The traceway is referred to the ichnogenus Kouphichnium, a locomotion trace attributed to xiphosurans. The traceway preserves telson grooves and different imprint morphologies from the various appendages. The traceway pattern and arrangement of the different traces suggest a crawling locomotion style. The sedimentology suggests a coastal zone with areas influenced by tides (intertidal flat). The morphological variations of the ichnites are correlated to substrate rheology, the locomotion of the tracemaker and environmental conditions

A new capitosaur from the Middle Triassic of Spain and the relationships within the Capitosauria

Ajuts: this research was supported by Synthesys (European Union−funded Integrated Activities) grant DE−TAF−5309 to JF.Capitosaurs were the largest and homogeneous group of Triassic temnospondyl amphibians with cosmopolitan distribution. However, their interrelationships are debated. The first capitosaur cranial remains found in the Iberian Peninsula were assigned to Parotosuchus; herein, a re−description of this material, together with information on other remains recovered from the same site, enables us to classify them as a new genus: Calmasuchus acri gen. et sp. nov. (Amphibia: Temnospondyli) from the early−to−middle Anisian (early Middle Triassic). This capitosaur had a combination of plesiomorphic and non−plesiomorphic characters, such as posterolaterally directed tabular horns, paired anterior palatal vacuities, and unique morphology of the lower jaw. By cladistic analysis, we propose a new phylogeny for the monophyletic capitosaurs. In the analysis, Capitosauria is supported by seven synapomorphies. Wetlugasaurus is the most basal member of the clade. The score of the Russian taxon Vladlenosaurus alexeyevi resulted in a clade including Odenwaldia and the latter taxa. The Madagascarian Edingerella is the sister taxon of Watsonisuchus. Finally, Calmasuchus acri, the new taxon described here, appears as a more derived form than Parotosuchus. The new genus is the sister taxon of the Cyclotosaurus-Tatrasuchus and Eryosuchus-Mastodonsaurus clades

Morphology and preliminary biomechanical interpretation of mandibular sutures in Metoposaurus krasiejowensis (Temnospondyli, Stereospondyli) from the Upper Triassic of Poland

Altres ajuts: CERCA Programme/Generalitat de CatalunyaThe morphology of the mandibular sutures in the Late Triassic temnospondyl Metoposaurus krasiejowensis has been examined in order to determine their role in mandible biomechanics. Until now, no histological studies of mandibular sutures in extinct vertebrates were performed, in contrast to cranial sutures. As a consequence, mandibular suture interpretations herein are based mainly on comparisons with previous studies of cranial sutures and with 3D cranial finite element analysis of this species. A total of 32 standard thin sections were studied under standard petrographic microscope observations in order to differentiate the morphology of mandibular sutures. Five mandibular suture types are present in this taxon: interdigitated, shallowly interdigitated, overlapping, tongue and groove and abutting. Based on previous work, it has generally been assumed that the shallowly interdigitated, tongue, groove and abutting suture types are associated with tension, the interdigitated type with compression and the overlapping type with absorption and counteraction of variable loads. The sutures associated with tension occur mainly in the anterior part of the mandible, principally in the dentary; overlapping sutures have been noted in medial portions of the mandible and sutures associated with compression mainly in posterior portions, i.e., in the angular and prearticular. The variability of suture types along the mandible suggests a complex loading regime of compression and tension. Sutures associated with tension and a flexible symphysis potentially allowed an increase of oral volume during gape opening, whereas sutures associated with compression represent adaptations for strong bite forces.Se ha examinado la morfología de las suturas mandibulares del temnospóndilo del Triásico Superior Metoposaurus krasiejowensis para determinar su papel en la biomecánica mandibular. Hasta la fecha, no se han realizado estudios histológicos de las suturas mandibulares de vertebrados fósiles, en contraste con los estudios histológicos en suturas craneales. Como consecuencia, las interpretaciones sobre las suturas mandibulares están aquí basadas en la comparación con estudios previos en suturas craneales y con análisis 3D de elementos finitos para esta misma especie. En total 32 laminas delgadas estándares fueron estudiadas con observaciones de microscopio petrográfico con el fin de diferenciar la morfología de las suturas mandibulares. Cinco tipos de suturas mandibulares son presentes en este taxón: interdigitales, levemente interdigitales, superposición, lengua, ranura y lindante. En base a estudios previos, se ha asumido generalmente que las suturas levemente interdigitales, lengua, ranura y lindantes se asocian con cargas de tensión, mientras que las de tipo interdigitales se asocian con compresión y el tipo sutural de superposición con distintas cargas de absorción y neutralización. Las suturas asociadas con tensión ocurren mayormente en la parte anterior de la mandíbula, principalmente en el dentario; las suturas de superposición se han encontrado las porciones mediales de la mandíbula y las suturas asociadas con compresión se han encontrado mayormente en las porciones posteriores, por ejemplo, en el angular y el prearticular. La variabilidad de los tipos suturales a lo largo de la mandíbula sugiere un complejo régimen de cargas de compresión y tensión. Suturas asociadas con tensión y una sínfisis flexible potencialmente permitieron un incremento del volumen oral durante la abertura bucal, mientras que las suturas asociadas con compresión representan adaptaciones a fuertes fuerzas de mordida

First direct archosauromorph remains from the Early-Middle Triassic transition of the Iberian Peninsula

This paper discusses the taxonomic affinities of three isolated teeth discovered in the Buntsandstein facies of the Catalan Coastal Ranges and central-eastern Pyrenean basins that crop out in Catalonia, north-eastern Spain. The tooth crowns are blade-like, labiolingually compressed, distally recurved, and proportionally apicobasally tall, in which the most complete of them is at least 2.4 times taller than its mesiodistal depth at base. The distal margins possess a densely serrated carina, and the mesial margins lack carina and serrations. The enamel of the crowns lacks ornamentation (e.g., wrinkles, ridges) or macroscopic wear-facets. The three teeth are referred to indeterminate crocopodan archosauromorphs based on the presence of labiolingually compressed and serrated crowns. The absence of mesial denticles resembles the condition in the non-archosauriform archosauromorph Teyujagua, proterosuchids, and some more crownward archosauriforms (e.g., some proterochampsids). We could not find evidence to determine if these teeth belong to a single or multiple closely related species. These remains represent the first direct archosauromorph remains from Lower−Middle Triassic beds of the Iberian Peninsula and add information about the geographic distribution of the group during the dawn of the evolutionary radiation of the group

Paleoneuroanatomy of the European lambeosaurine dinosaur Arenysaurus ardevoli

The neuroanatomy of hadrosaurid dinosaurs is well known from North America and Asia. In Europe only a few cranial remains have been recovered that include the braincase. Arenysaurus is the first European endocast for which the paleoneuroanatomy has been studied. The resulting data have enabled us to draw ontogenetic, phylogenetic and functional inferences. Arenysaurus preserves the endocast and the inner ear. This cranial material was CT scanned, and a 3D-model was generated. The endocast morphology supports a general pattern for hadrosaurids with some characters that distinguish it to a subfamily level, such as a brain cavity that is anteroposteriorly shorter or the angle of the major axis of the cerebral hemisphere to the horizontal in lambeosaurines. Both these characters are present in the endocast of Arenysaurus. Osteological features indicate an adult ontogenetic stage, while some paleoneuroanatomical features are indicative of a subadult ontogenetic stage. It is hypothesized that the presence of puzzling mixture of characters that suggest different ontogenetic stages for this specimen may reflect some degree of dwarfism in Arenysaurus. Regarding the inner ear, its structure shows differences from the ornithopod clade with respect to the height of the semicircular canals. These differences could lead to a decrease in the compensatory movements of eyes and head, with important implications for the paleobiology and behavior of hadrosaurid taxa such as Edmontosaurus, Parasaurolophus and Arenysaurus. The endocranial morphology of European hadrosaurids sheds new light on the evolution of this group and may reflect the conditions in the archipelago where these animals lived during the Late CretaceousPeer Reviewe