Abstract Recent ichnological analysis conducted in two sections (Rodiles and Lastres) of the Asturian Basin revealed the presence of Halimedides Lorenz von Liburnau 1902 , which occurs just above the black shales related to the end of the Toarcian Oceanic Anoxic Event (T-OAE). Halimedides is associated with recovery of the trace-maker community after the re-establishment of favourable, oxic, conditions. The appearance of Halimedides after the T-OAE event, previously not registered, supports the close relationship of the trace maker with oxygen conditions, as occurs in other anoxic events including the Cretaceous OAE-1a and OAE-2. Also, a relationship between morphometric and palaeoenvironmental parameters is observed: occurring larger and densely chambered specimens in darker, weakly oxygenated facies, while smaller and sparsely chambered forms are registered in lighter, better oxygenated sediments.

Abstract Wilhelm Schulz (1805–1877), known in Spain as Guillermo Schulz, was one of the most outstanding representatives of the geology and mining industry in Spain during the nineteenth century. Schulz is, likewise, the author detailing the first discoveries of dinosaurs and marine reptiles in Spain. In 1858 Schulz described a supposed dinosaur tooth from the Jurassic of Ruedes (Asturias) as belonging to a shark. Schulz's description, mainly the occurrence of crenulated edges, suggests that the tooth was that of a large theropod. It probably comes from the altered grey marls of the Upper Jurassic (Kimmeridgian) Lastres Formation. Although the exact year of the discovery before 1858 is not known, the Ruedes tooth (currently lost) is presumably the earliest known discovery of a dinosaur body fossil in the Iberian Peninsula. Moreover, Schulz mentioned in 1858 the discovery of plesiosaur remains from the Liassic near Villaviciosa (Asturias). The material probably comes from the Pliensbachian marls and limestone rhythmites (Jamesoni zone) of the Rodiles Formation. As no figure was provided and the specimen is currently lost, we have no definitive certainty about its affinities. However, it represents the earliest marine reptile fossil found in Spain.

Abstract At the beginning of the Jurassic period, southern European areas formed a single continental mass open to the east (western Tethys), and the Iberian plate lay between latitude 25°N and 35°N. It was separated from the larger European plate to the north by a narrow trough corresponding to the early rifting of the Bay of Biscay. To the NW it was separated from the Laurentia–Greenland Plate by an epicontinental sea showing a typical horst and graben structure, which would eventually become the palaeogeographical connection between the northern and central Atlantic. The opening of the Bay of Biscay took place between latest Jurassic and early Campanian times, giving rise to SE-directed movement and anti-clockwise rotation of the Iberian plate (e.g. Ziegler 1988 b ; Osete et al . 2000 ). Jurassic palaeogeography was characterized by a large part of the central and western Iberian plate forming an emergent massif (the so-called Iberian Massif), whilst the surrounding areas were occupied by intracratonic basins that formed shallow epicontinental seas, predominantly filled with marine carbonate deposits (Fig. 11.1 ). Those areas, located to the north and NE of the Iberian Massif, correspond from west to east to Asturias, the Basque-Cantabrian basin, and the South Pyrenean basin. To the east extended the Iberian basin, whereas the southern margin of the Iberian Massif was occupied by a wide carbonate platform parallel to a narrow oceanic trough connecting Tethys with the central Atlantic Ocean. These areas together comprised the south Iberian margin basin, whose proximal