Macronarios del Jurásico Superior de Portugal en el 73rd Annual Meeting de la SVP

A comienzos de Noviembre se presentó en el 73rd Annual Meeting de la Society of Vertebrate Paleontology celebrado en Los Angeles, y en forma de poster, nueva información sobre los macronarios basales del Jurásico Superior Portugués. Con el título de “Macronarian record from the Upper Jurassic of Portugal”, esta comunicación iba firmada por los investigadores Pedro Mocho (Universidad Autónoma de Madrid/Sociedade de História Natural), Rafael Royo-Torres (Fundación Conjunto Paleontológico de Teruel-Dinópolis), Francisco Ortega (Grupo de Biología Evolutiva, UNED) y Bruno Camilo Silva (Sociedade de História Natural). En este trabajo se hace una pequeña reseña sobre el estado actual de conocimiento de estos saurópodos del Jurásico Superior de Portugal, integrando la información procedente de los taxónes clásicos (Lourinhasaurus y Lusotitan) y algunos ejemplares fragmentarios, así como nuevo material proveniente de Torres Vedras y Lourinhã (Portugal).

El resumen es el siguiente:

New macronarian remains from the Portuguese Upper Jurassic are discussed. Some of those were found in Cambelas (Freixial Formation, Torres Vedras), Baleal (Praia da Amoreira-Porto Novo Formation, Peniche) and Peralta (Sobral Formation, Lourinhã) consisting of cranial (teeth) and postcranial material that could be assigned to basal macronarians. The study of several Portuguese classical remains also increases our knowledge of this group during Upper Jurassic. The reassessment of type specimens of Lourinhasaurus alenquerensis (Sobral Formation, Alenquer) and Lusotitan atalaiensis (Sobral Formation, Peralta) with the description of several unpublished and still undescribed elements allows us to refer these two taxa to Macronaria (also supported by cladistic analysis).

The presence of fully opisthocoelus condition up to the sacral vertebrae, horizontally projected diapophysis, and “plank”-like cranial dorsal ribs, which are common synapomorphies of basal macronarians, are used to relate these specimens with this group. At present, it is possible to identify one basal macronarian form close related to Camarasaurus. On the other hand, there are various specimens bearing several basal titanosauriform features, such as the camellate presacral bone, a lateral bulge on the femur, dorsal and caudal centra dorsoventrally compressed, cone-chisel-like teeth and a gracile humerus. Further analyses will discriminate if they represent one or two different
taxa.

Recent works suggested that the Upper Jurassic-Lower Cretaceous (upper Oxfordian–lower Berriasian) sauropod faunas of Iberian Peninsula are composed by exclusive taxa (Lourinhasaurus, Lusotitan, Dinheirosaurus, Aragosaurus, Galveosaurus, Losillasaurus and Turiasaurus) although some of them are related to sauropod groups represented in Upper Jurassic strata of other continents such as brachiosaurids, diplodocids and camarasaurids. This situation is opposite to what is suggested by other groups of dinosaurs (such as stegosaurs or theropods) with a proposed North American-European Upper Jurassic distribution, putting forward a vicariance model to explain their diversity in this territory.