Análisis mediante morfometría geométrica de un fémur de alosáurido del Jurásico Superior de Pombal en las XXXVIII Jornadas de la SEP

Durante estos últimos días se celebraron las XXXVIII jornadas de la Sociedad Española de Paleontología (SEP) en Valencia. Entre la gran cantidad de trabajos científicos, se presentó “Geometric Morphometric analysis of an Upper Jurassic allosaurid (Dinosauria, Theropoda) femur from Pombal (Portugal)”, en el cual se compararon las vistas medial y posterior de un fémur de alosáurido del yacimiento de Andrés, del Jurásico Superior de Portugal, con otras de terópodos jurásicos sobre todo de América del Norte y Europa, mediante morfometría geométrica 2D, para inferir en la sistemática de los alosáuridos encontrados en este yacimiento. Los resultados obtenidos al realizar análisis de componentes principales (PCA), lineales discriminantes (LDA) y de agrupamiento jerárquico (cluster) ponen de manifiesto que nos encontramos ante un alosáurido muy cercanamente emparentado con el norteamericano Allosaurus fragilis, pero la falta de fémures de Allosaurus europaeus no permite más comparaciones. El futuro estudio de más fósiles de alosáuridos de Andrés, y la aplicación de morfometría geométrica 3D, darán más pistas sobre la diversidad de este grupo durante el Jurásico Superior de la Cuenca Lusitánica. El resumen de este trabajo se muestra a continuación:

Allosaurus is one of the best-known dinosaurs from the Upper Jurassic, with most occurrences in the Morrison Formation, USA, but also identified in the Lusitanian Basin in Portugal. Allosaurus has been found in two different continents, with large number of specimens, and this have led to intense debate about the intraspecific and interspecific variability within this genus. Numerous species have been described, but currently only Allosaurus fragillis and Allosaurus jimmadseni in the Morrison Formation, and Allosaurus europaeus in the Lusitanian Basin are consider valid. The Andrés fossil site (near Pombal, Portugal) has yielded several theropod remains previously assigned to A. fragilis and more recently tentatively interpreted as belonging to Allosaurus cf. europaeus, with as many as three different individuals. Here we compare a left femur from Andrés (MNHNUL.P.AND67) with other theropod femora from the Jurassic, mainly from North America and Europe, using 2D Geometric Morphometrics. We tested the hypothesis that the femur from Andrés represents an allosaurid other than A. fragilis. For that, we created a 3D model of the femur using photogrammetry and then extracted the medial and posterior views, that are the most common in the literature and placed the relevant landmarks. Multivariate statistical analyses, such as Principal Component Analysis (PCA), Linear Discriminant Analysis (LDA), and Cluster Analysis were performed to visualize the position of the Andrés specimen respect the morphospaces of other allosaurid theropods. The preliminary results show that the studied femur is characterized by a set of morphometric variables that are similar to A. fragilis, but also, to a lesser extent, to A. jimmadseni and Lourinhanosaurus antunesi. Further research and the application of 3D Geometric Morphometrics in this femur as well as in other theropod bones from Andrés will provide new data to support this hypothesis.