Neuroanatomy of the crocodylomorph Portugalosuchus azenhae from the late cretaceous of Portugal
Creators: name: Eduardo Puértolas Pascual
Publisher: name: Zenodo
Year: 2023
Subjects: 3d models
tac
neurocranial
late cretaceous
micro CT
crocodilemorph

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: 
This study presents the first detailed description of the neurocranial anatomy and neuroanatomical analysis of Portugalosuchus azenhae, a eusuchian crocodilemorph from the Late Cretaceous of Portugal. Although it was originally classified as a possible Crocodylia and one of the oldest representatives of this clade, its phylogenetic position remains controversial. Using high-resolution microtomography images, this study aimed to improve the original description of the taxon and update the scarce neuroanatomical knowledge of Eusuchia and Crocodylia from this time interval, crucial to understanding the origin and evolution of these clades. The resulting three-dimensional models of the CT data allowed a detailed description of the neurocranium and well-preserved internal cavities. This made possible the reconstruction of the cavities of the olfactory region, nasopharyngeal ducts, brain, nerves, carotid arteries, blood vessels, paratympanic sinus system and inner ear, which made it possible to estimate some neurosensory capacities. Compared with other crocodiles, these analyzes demonstrated that Portugalosuchus, already in the Cretaceous, possessed olfactory acuity, vision, hearing and cognitive abilities within the range observed in other extinct eusuchians and modern crocodiles. Furthermore, the new anatomical data provided by the TAC were included in a phylogenetic analysis. The position of Portugalosuchus differs slightly from the original publication, now placing it in a Gavialoidea, within the Crocodylia clade. 
 
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