Implicaciones etologicas y significado de la estereotipicidad de Oichnus Bromley durante el plioceno en la cuenca del bajo Guadalquivir (SO España)

The analysis of the stereotypy in the Oichnus-type borings on Bivalvia(epiandinfaunal) from different Pliocene stratigraphic horizons in the Southwestern sector of the Guadalquivir Basin, has allowed us to show some changes about the predatory behavior. These have an effect on two levels: on a small scale, when the changes between juvenile and mature states of the prey are considered, and on a larger scale, when the environmental conditions of every stratigraphic horizon are estimated. The variability in the first case is due to internal factors of the predatory-prey system:morphology, size, and ornamentation of the prey. On the second one, it is related to loss or increase in external factors on the system: environmental selective pressure (kind of substrate,energy, ecological competition). Well-defined behavior patterns have