New data on the neuroanatomy of basal eusuchian crocodylomorphs (Allodaposuchidae) from the Upper Cretaceous of Spain
Creators: name: Eduardo Puértolas Pascual
Publisher: name: Zenodo
Year: 2023
Subjects: Micro CT
Upper Cretaceous
cocodrylomorpha
vertebrates
Paleogene
fossils
3d models

description: Objectives:
The services providedby the CENIEH, in this casethe application of Computed Microtomography (microTAC) to fossilbones, have beenused several times. The main goalhas been toscan Mesozoic vertebrates, mainly crocodiles, with the intentionof seeing cavitiesand other internalstructures that are usually hiddenor inaccessible due to the rocky matrix thatcontains the fossil. The purpose ofthe data obtainedfrom the microTACcan be summarizedas:- Internal anatomyof fossils: CTscans allow paleontologiststo visualize theinternal structures of fossils withouthaving to damagethem. This includesbones, teeth, softtissues, and insome cases even preserved organs.- Three-dimensional reconstruction: From the images obtainedwith the TACscanner, accurate 3D models of the fossils canbe created. Thisfacilitates the detailed study ofmorphology and allows the analysis offunctional and evolutionary aspects.- Taxonomic comparisons: The CT scanis a valuabletool that allowsto observe anatomicalfeatures that maybe hidden fromthe naked eye, such as sutures, internal cavities, etc. Obtaining thisinformation is very useful forclassifying and comparing extinct specieswith other knownones. This helpsto determine evolutionaryrelationships and to understand pastbiodiversity.- Behavioral study: By analyzing fossilsin their three-dimensionalcontext, scientists can infer aspectsof the behaviorand ecology ofextinct organisms. In our case, the CT imagesand 3D modelsgenerated can beused for paleoneuroanatomystudies. Paleoneuroanatomy is a branch of paleontology thatfocuses on thestudy of thebrain structures and nervous systemof extinct organismsthrough the analysisof fossils andendocranial molds. Its goal is to reconstruct andunderstand the brain anatomy ofancient species to gain informationabout their behavior, cognitive ability and evolution. GettingThree-Dimensional Imaging: CT scans use X-rays to getdetailed pictures of the interiorof the skulland other tissues. These images aregenerated in cross-sectionsand then combinedto create accurate3D models ofthe endocranial cavity. CT scansidentify and mapor segment impressionsand internal characteristicsof the skull, which correspond to brain structuressuch as thebrain, cerebral ventricles, olfactory bulbs, inner ear, and other partsof the nervoussystem. From thesedata, accurate measurements of theendocranial cavity can be made and compared withmodern species to infer aspectsrelated to thesize and shapeof the brainof fossil organisms. This allows inferencesto be madeabout the cognitive, sensory and behavioralcapacities of fossilorganisms. For example, it ispossible to estimatecognitive, visual, olfactory, auditory skills, etc. Thus, comparingfossil brains withthose of modernspecies helps tounderstand the evolution of thenervous system and provides informationabout changes inbehaviour and cognitionover time. 
Study:
The Pyrenees (northeast of Spain) has provided a rich and diverse collection of fossil remains of vertebrates from the Upper Cretaceous, among which the Crocodylomorpha stand out. This record includes remains of the last representatives of the crocodiles of the family Allodaposuchidae, to which the species from the Aragonese record Arenysuchus gascabadiolorum and Agaresuchus subjuniperus belong. This clade is related to extant crocodiles and disappeared at the same time as non-avian dinosaurs during the Cretaceous-Paleogene (K/Pg) extinction event. In this context, the holotype skull of Arenysuchus gascabadiolorum was subjected to a microtomography scanner at the CENIEH facilities to obtain the three-dimensional reconstruction of its internal cranial cavities, including the brain, nerves, blood vessels, paratympanic sinus system and paranasal sinuses. These cavities were compared with those of other crocodilemorphs and it was observed that the endocranial anatomy is consistent with its phylogenetic position within Allodaposuchidae and showing morphologies and neurosensory and cognitive capacities similar to those present in other allodaposuchids. Their inferred sensory capabilities, such as a keen sense of smell and relatively good vision, are within the range observed in most eusuchians and Crocodylia, suggesting that the sensory and cognitive abilities observed in late Mesozoic crocodiles were already similar. to those observed in modern crocodiles. 
 
This report acknowledges the financial support of the Access to Research Infrastructures                 activity in the H2020-INFRAIA-2019-1 of the EU (IPERION HS Grant Agreement n. 871034)