Yacimiento: Arén (Blasi), Huesca

Ichnites The sites with Cretaceous dinosaur ichnites at Arén are located on the north flank of the Tremp syncline, a synclinal of the upper block of the Montsec intraplate fold. The rocks that contain them were deposited in a regresssive delta environment in the Upper Cretaceous foredeep basin of the southern Pyrenees. Towards the basin, which opens towards the Atlantic Ocean, the sandstones grade to pro-delta pelites and turbidites, whereas towards the continent they become transition and fluvial sediments (Areniscas de Arén Formation and Tremp Formation respectively). The existence of dinosaur remains at Areny has been known since 1992, when the site of the dinosaur tracks was discovered and given the name “Arén”. With a view to preserving the site, changes were made to the route taken by the road between Lleida and France, which had initially passed through the site locality. At first, nine ichnites appeared on the fossiliferous level, spread over roughly 15m, while the rest was covered by talus and the western part of the upper stratum. For this reason, during the summer of 2000, an excavation was carried out that made it possible to distinguish two levels with ichnites (Areny I and II). Bone Remains The dinosaur sites in the municipality of Arén are located in the region of Ribagorza in the Pyrenees of Huesca. Six sites have been located at Blasi. These we have named Blasi 1 to Blasi 6, ranging from the oldest to the newest in geological terms. They are situated on the north flank of the Tremp syncline, a synclinal of the upper block of the Montsec intraplate fold. The rocks that contain them were deposited in a regresssive delta environment in the Upper Cretaceous foredeep basin of the southern Pyrenees. Towards the basin, which opens towards the Atlantic Ocean, the sandstones grade to pro-delta pelites and turbidites, whereas towards the continent they become transition and fluvial sediments (Areniscas de Arén Formation and Tremp Formation respectively). The Arén dinosaurs form part of a whole series of dinosaur discoveries made in Aragon in the course of 1997 that made the local, national and international news. They were found by the geologists L. Ardèvol and F. López Olmedo during field work they were doing to the west of the town of Areny itself. Ichnites The sites with Cretaceous dinosaur ichnites at Arén are located on the north flank of the Tremp syncline, a synclinal of the upper block of the Montsec intraplate fold. The rocks that contain them were deposited in a regresssive delta environment in the Upper Cretaceous foredeep basin of the southern Pyrenees. Towards the basin, which opens towards the Atlantic Ocean, the sandstones grade to pro-delta pelites and turbidites, whereas towards the continent they become transition and fluvial sediments (Areniscas de Arén Formation and Tremp Formation respectively). The existence of dinosaur remains at Areny has been known since 1992, when the site of the dinosaur tracks was discovered and given the name “Arén”. With a view to preserving the site, changes were made to the route taken by the road between Lleida and France, which had initially passed through the site locality. At first, nine ichnites appeared on the fossiliferous level, spread over roughly 15m, while the rest was covered by talus and the western part of the upper stratum. For this reason, during the summer of 2000, an excavation was carried out that made it possible to distinguish two levels with ichnites (Areny I and II). Bone Remains The dinosaur sites in the municipality of Arén are located in the region of Ribagorza in the Pyrenees of Huesca. Six sites have been located at Blasi. These we have named Blasi 1 to Blasi 6, ranging from the oldest to the newest in geological terms. They are situated on the north flank of the Tremp syncline, a synclinal of the upper block of the Montsec intraplate fold. The rocks that contain them were deposited in a regresssive delta environment in the Upper Cretaceous foredeep basin of the southern Pyrenees. Towards the basin, which opens towards the Atlantic Ocean, the sandstones grade to pro-delta pelites and turbidites, whereas towards the continent they become transition and fluvial sediments (Areniscas de Arén Formation and Tremp Formation respectively). The Arén dinosaurs form part of a whole series of dinosaur discoveries made in Aragon in the course of 1997 that made the local, national and international news. They were found by the geologists L. Ardèvol and F. López Olmedo during field work they were doing to the west of the town of Areny itself. The excavations began in 1997. In the course of them, hundreds of articulated and disarticulated remains of dinosaurs and other vertebrates have been recovered. These sites have a dual importance: on the one hand the great quantity and high quality of the remains recovered so far, and on the other the fact that they are the most modern sites from the end of the Cretaceous to have been found in Europe. This makes the Arén sites a reference point on a worldwide scale in the study of the extinction of the dinosaurs in this part of Europe. The dinosaur fossil remains from the Blasi sites are abundant and well-conserved, including two partially articulated hadrosaur crania, one in Blasi 1 and the other in Blasi 3. Their extraction and laboratory treatment are slow because the sites are conserved in very hard sandstones. For this reason part of the material is still in the process of being prepared. In a preliminary study, eight species of dinosaurs have been recognised, of which the hadrosaurs are the most abundant.