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Six new dinosaurs sites have been found close to the Cretaceous/Tertiary boundary in Arén (south-central Pyrenees, Huesca, Spain) in coastal and non-marine deposits of the Arén and Tremp Formations. The sites contain articulated remains (skull elements, vertebrae, hind-limb bones) and isolated teeth and bones of hadrosaurids, three types of theropod teeth, one sauropod, at least seven types of eggshells (six ornithoid types and one Megaloolithidae probably from a sauropod), remains of other vertebrates, and four charophyte species. The fossil-bearing rocks have been correlated with marine sediments containing planktonic foraminifera from the uppermost Maastrichtian Abathomphalus mayaroensis Biozone. These rich and diversified dinosaur assemblages enable more accurate dating of the faunal changes that took place during the Maastrichtian in Europe and support the hypothesis of a sudden dinosaur extinction at the Cretaceous/Tertiary boundary. Academic Press

Amenability to radiometric dating. Unknown, but absolute cyclostratigraphic dating is possible. Amenability to magnetostratigraphy. Yes, chrons C22n, C21r, C21n and C20r have been identified. Amenability to chemostratigraphy. Yes, but work is still in progress. Accessibility. Excellent. Free access. Yes, the section is located in a public beach. Permanent protection of the site. Yes. The whole coast is protected by the Spanish Littoral Law (22/1988, July 28); the Gorrondatxe beach is specially protected in order to preserve the endangered Natterjack toad (Epidalea calamita) from regional extinction. Local institutions (town and regional councils, University of the Basque Country) are willing to cooperate. Possibility to fix a permanent marker. Yes. Once the GSSP is approved, a permanent marker (a metal plate) will be fixed. Local institutions (town and regional councils, University of the Basque Country) are willing to cooperate.

Thirteen Lower–Middle Eocene (Ypresian–Lutetian) successions, including the Gorrondatxe section in the western Pyrenees, show biomagnetostratigraphic correlation schemes that do not agree with the current standard framework. The main discrepancy concerns the position of the boundary between planktonic foraminiferal Zones P9 (=E7, approximately) and P10 (=E8, approximately), which was thought to occur within calcareous nannofossil Subzone CP12a and at the boundary between magnetic polarity Chrons C22n and C21r. However, in the differing correlation scheme the boundary between Zones P9 (=E7) and P10 (=E8) occurs close to the base of Subzone CP13a and to the boundary between Chrons C21n and C20r. An attempt at a new Ypresian–Lutetian boundary biomagnetochronology is made based on data from the Gorrondatxe section, which shows that the boundary between Zones P9 (=E7) and P10 (=E8) is 3.1 Myr younger than hitherto considered. Therefore, the duration of the Early Eocene, most commonly defined according to this planktonic foraminiferal zonal boundary, has generally been underestimated over the last four decades.