Reassessment of Laplatasaurus araukanicus (Sauropoda: Titanosauria), from the Late Cretaceous of Patagonia, Argentina

GALLINA, P. A.; OTERO, A.

Jornada; Jornadas Argentinas de paleontología de vertebrados; 2015

The original material assigned to Laplatasaurus araukanicus Huene come from five different localities in northern Patagonia (Argentina)where the Upper Cretaceous (Campanian) lies exposed. This material includes several postcranial bones from multiple specimens andshowing different conditions of preservation, often lacking anatomical overlap. The taxonomic status of the taxon is further obscured by theabsence of quarry maps of the multiple localities (lacking the recognition of associated materials), and a proper designation of type materialin its original description. After Huene, new material was assigned to this taxon, although none of it resolved the existing taxonomic issues. In1979, the designation of a lectotype (one tibia and one fibula) was the first stage in the nomenclatural stabilization of the species. However,the assignment of the remaining material to L. araukanicus remained uncertain. Here we review all the material hitherto assigned to this taxonin order to clarify its taxonomic status. We also provide a re-description of the lectotype and discuss the taxonomic identification of materialpreviously referred to this taxon. Lastly we include it for the first time in an updated phylogenetic data matrix. Laplatasaurus araukanicus is retainedonly for the lectotype. The material from Rancho de Ávila is referred to cf. Bonitasaura sp. because they share diagnostic features andare stratigraphically congruent. The remaining material is referred as Lithostrotia indet. A phylogenetic analysis nests Laplatasaurus withinTitanosauria in a clade formed by ((Laplatasaurus + Uberabatitan) + (Bonitasaura + (Futalognkosaurus + Mendozasaurus))).