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: The influence of substrate firmness as shear strength on the nesting behavior of the wasp Bembix oculata is analyzed in “natural” conditions. The experimental area (a landing pit at the athletics stadium in Granada, southern Spain), is characterized by the existence of a non-random distribution of nesting holes made by Bembix oculata. The analysis of sediment features shows homogeneity in some substrate properties such as grain size and mineralogy. However, the quantitative analysis of substrate firmness leads to recognition of a close relationship between shear-strength values and burrow distribution. Experiments performed by Torvane testing in 13 sampling sites reveal changes in shear strength related to variations in water content of the substrate. These changes in shear strength are closely associated with distribution of nests. Thus, a gradual increase in substrate shear strength, over 1000-1500 Pa, is recorded toward the area where nesting holes appear, whereas burrows are most abundant where shear strength is higher (above 2500 Pa). Substrate firmness is revealed to be of prime importance in the nesting behavior of Bembix oculata. The relationship between the obtained shear-strength values and the soil water content could be interpreted as the influence of water content in substrate firmness. However, we do not discard the influence of water content as an independent factor (soil moisture).

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