Las vértebras dorsales de los titanosaurios de Lo Hueco en las VII Jornadas de Salas de los Infantes

En las VII Jornadas Internacionales sobre Paleontología de Dinosaurios y su Entorno en Salas de los Infantes (España), se ha presentado una nueva comunicación sobre saurópodos titanosaurios del yacimiento de Lo Hueco (Cretácico Inferior) en Cuenca. Este trabajo liderado por Pedro Mocho (Grupo de Biología Evolutiva de la UNED) se centra en el estudio de elementos presacrales, en particular de vértebras dorsales. Su estudio detallado ha permitido describir dos morfotipos de vértebras dorsales en el yacimiento de Lo Hueco, y un tercero que presenta afinidades con el titanosaurio Lirainosaurus, especie exclusiva del Cretácico Superior de la península ibérica. También se ha podido comparar y discutir posibles afinidades con otros titanosaurios del registro iberoarmoricano.

In 2007, a singular accumulation of fossils representing individuals of some lineages of continental tetrapods was found at Lo Hueco (Fuentes, Cuenca) in the southwestern branch of the Iberian Ranges (central Spain). The fossil site of Lo Hueco is placed in sediments belonging to the upper part of the Margas, Arcillas y Yesos de Villalba de la Sierra Formation, late Campanian‐early Maastrichtian in age. Sauropods, in particular titanosaurs, are the group of vertebrates best represented in the site. Up to now, the comparison of these partial skeletons with the isolated remains indicates the presence of at least two different titanosaurian morphotypes based on two types of cranial morphologies, appendicular bones and teeth. The Lo Hueco site has yielded several titanosaurian partial skeletons in anatomical connection or with a low level of dispersion of their skeletal elements. Among them several fully and partially articulated presacral vertebrae were found, presenting an almost complete spectrum from the anterior to posterior dorsal vertebrae, being some of them associated to relatively complete skeletons. These elements are an important source of information for the morphological data matrices and they are particularly rare in the European Upper Cretaceous record. Some of the found dorsal vertebrae are herein briefly described. One of the most important specimens corresponds to an articulated anterior to middle dorsal vertebrae series that are now in preparation. These titanosaur dorsal vertebrae of Lo Hueco show several features that are commonly shared by titanosaurs, such as: i) a single prespinal lamina in middle and posterior dorsals, ii) presence of a reduced and eye‐shaped pneumatic foramen in the lateral surface of the centra, iii) transverse process setting off from the dorsal surface and with a distinct dorsally facing flattened area, iv) absence of the spinoprezygapophyseal lamina (sprl); v) strongly posterior oriented anterior and middle dorsal neural spines. Currently it is possible to identify two or three different dorsal vertebral morphotypes in Lo Hueco site that could represent, at least, two different taxa. Two of them belong to medium‐to‐large sized individuals, and they mainly differ in the morphology of the neural arch, in particular in the lateral development of the triangular aliform process and the proportion between the neural spines and the centrum). Other small dorsal vertebrae with fused neural arches differ from the larger vertebral morphotypes. This third morphotype is featured by the presence of subvertical neural spines and sprl in the anterior dorsal vertebrae, and shares its general morphology with the anterior dorsals of Lirainosaurus. One of the most important features present in the middle and posterior dorsal vertebrae of Lo Hueco titanosaurs is the presence of a subvertical crest below the intrapostzygapophyseal laminae. This crest is present, at least, in one of the large morphotypes and in the smaller one, and it is interpreted herein as a hyposphenic crest similar to that present in the French titanosaur Ampelosaurus. The morphology of presacral vertebrae is poorly known in the European titanosaurs. The phylogenetic position of the titanosaurian taxa from Lo Hueco is still uncertain, but they represent derived titanosaurs within Lithostrotia. Further incorporation of all European taxa in new morphological data matrices and detailed comparative studies of those taxa are still necessary to understand the evolutionary history of this group in the European territory during the Late Cretaceous.

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Más información:

• Mocho, P., Páramo, A., Díez Díaz, V., Escaso, F., Marcos-Fernández, F., Sanz, J. L., Ortega, F. 2016. Looking through the axial skeleton of the Lo Hueco titanosaurs. In: Torcida Fernández-Baldor, F., Canudo, J.I., Huerta, P., Pereda, X. (eds.) Abstracts book of the VII International Symposium about Dinosaurs Palaeontology and their Environment, 99-100.