Bivalves du Trias tariquide de Los Pastores (Algésiras), Espagne. Leur signification

A fossiliferous limestone slab from the Triassic locality of the Roch of Los Pastores (Algesiras W), yielded two beds of a bivalve faunule. The bivalves are preserved as dissociated valves of internal moulds on the upper side of the slab and as unidentifiable external moulds on its lower side. Seven species, similar with taxa known from other localities in Spain have been identified: ?Gervillia joleaudi, Leptochondria alberti, ?Posidonia obliqua, Costatoria (Costatoria) goldfussii, Lyriomyophoria sublaevis, Neoschizodus (N.) laevigatus, Pseudocorbula gregaria. The significance of this assemblage is considered after a systematic study: (1) according to the stratigraphical distribution of these seven species, particularly among the Germanic, the Alpine-tethyan and the Spanish Triassic realms, the age suggested is upper Ladinian-lower Carnian; (2) some correlations appear with the association: ?Gervillia joleaudi, Leptochondria alberti, Neoschizodus laevigatus, Myophoria goldfussii, Lyriomyophoria sublaevis; this last species is known from several fossilerous localities in the Catalanid and Betic Ranges into the "Sephardic" realm. However, the studied bivalve assemblage, with the dominant species Lyriomyophoria sublaevis, shows a characteristic biofacies, endemic of this southern province of Andalusia; (3) the Lyriomyophoria biofacies, with its condition of preservation, signifies a high energy, shallow, marine paleoenvironment.