In this work based on her doctoral thesis, Carole Fritz presents the remarkable contribution that observation with a scanning electron microscope brings to the study of engraving in Magdalenian portable art. This original and rigorous scientific approach opens up particularly promising paths of research. A corpus of sixty objects made of bone and antler, found at eight middle and upper Magdalenian sites m the area bounded by the Pyrénées, the Gironde estuary and the Dordogne river, is methodically analysed. On the basis of this analysis, backed by a previously unpublished and quite exceptional iconography, the author proposes fresh thinking on the artistic gestures of the Magdalenian period, on the operational processes corresponding to mental patterns and collective practices, on the modalities of acquisition and transmission of know-how and skills, and ultimately, on the existence of a thought-out artistic phenomenon in the societies of this epoch.