Verónica Díez Díaz

Appendicular skeleton and dermal armour of the Late Cretaceous titanosaur Lirainosaurus astibiae (Dinosauria: Sauropoda) from Spain

Lirainosaurus astibiae is the best-known titanosaurian sauropod species from the Iberian Peninsula. It was described by Sanz and collaborators in 1999 on the basis of several cranial and postcranial remains from the Late Cretaceous of Laño (northern Spain); new remains from this and other Iberian fossil-sites have recently been referred to this species. This paper focuses on the description of the appendicular skeleton and dermal armour of Lirainosaurus. Comparison with other European titanosaurs confirms that Lirainosaurus astibiae clearly differs from them, and highlights two diagnostic appendicular features: the presence of a dorsal prominence together with a ventral ridge on the medial surface of the scapular blade, and the combination of an anterolateral process and an anteroventral ridge on the sternal plate. Equations for predicting body mass and size in sauropods suggest a body size up to 6 meters and a body mass of at least 2-4 tonnes for the largest individuals of Lirainosaurus astibiae, it being one of the most slender titanosaurs found to date. The study of the non-axial postcranial skeleton supports the hypothesis that Lirainosaurus astibiae is a derived lithostrotian close to Saltasauridae. Verónica Díez Díaz. Universidad del País Vasco/Euskal Herriko Unibertsitatea, Facultad de Ciencia y Tecnología, Apdo. 644, 48080 Bilbao, Spain. diezdiaz.veronica@gmail.com Xabier Pereda Suberbiola. Universidad del País Vasco/Euskal Herriko Unibertsitatea, Facultad de Ciencia y Tecnología, Apdo. 644, 48080 Bilbao, Spain. xabier.pereda@ehu.es José Luis Sanz. Universidad Autónoma de Madrid, Facultad de Ciencias, Dpto. Biología, Ud. Paleontología, 28049 Cantoblanco, Madrid, Spain. dinoproyecto@gmail.com

Braincase Anatomy of the Titanosaurian Sauropod Lirainosaurus astibiae from the Late Cretaceous of the Iberian Peninsula

Lirainosaurus is the only titanosaurian sauropod described to date from the Late Cretaceous of the Iberian Peninsula. The type of Lirainosaurus astibiae consists of both cranial and postcranial remains that were found as disarticulated elements in the Laño quarry (Treviño, northern Spain). This taxon was diagnosed originally on the basis of vertebral and appendicular autapomorphic traits. The study of a paratypic skull fragment and a second referred specimen provides information about its braincase morphology. Lirainosaurus is regarded as a derived titanosaur on the basis of the complete fusion between the prootic and the exoccipital-opisthotic complex, the position of the cranial foramina, and the shape and orientation of the occipital condyle. The braincase of L. astibiae appears to be diagnostic in the presence of a foramen distally on each basal tubera. The absence of median subcondylar foramina in the basioccipital may be an autopomorphic trait or be due to ontogenetic growth. A comparison with other partial skulls known in Europe suggests a high diversity during the Campanian/Maastrichtian, with at least three different titanosaurian species living in the Ibero-Armorican Island.