4.1.-The Coll de Nargó nesting area

摘要: Nowadays, and especially after the discovery of in ovo titanosaur embryos in megaloolithid eggs at Auca Mahuevo (Argentina), most of specialists assume that eggs of this oofamily correspond to titanosaurs. Therefore, in many basins of southern Europe, the megaloolithid egg record is a potential source of evidence to assess the nesting habits of this group of sauropods. In the southern Pyrenees, outcrops of the Late Cretaceous Tremp and Arén Sandstone Formations yielded for many years thousands of eggs and in situ clutches. In that respect, the Coll de Nargó Syncline contains an extensive record of eggshells, eggs and clutches that represents one of the most interesting samples in order to evaluate the titanosaur nesting behaviour.The so-called nesting area of Coll de Nargó occurs in the drainage of the Sallent River in the southern Pyrenees of western Catalonia. It comprises several continental outcrops with abundant egg localities. From west to east the main localities are Sallent, Pinyes, Santa Eulària, Codó, Els Enserris, being the Pinyes site one of the most important (Figure 28). Localities are located in the basal units of the Tremp Formation (Upper Cretaceous-lower Paleocene), a formation historically referred to as the Garumnian facies of the southern Pyrenees (see review in Rosell et al. 2001). Most of egg clutches represent nesting activities of sauropods in ancient floodplain environments.