The origins of figurative art have been widely discussed over the past several decades. First, researchers spoke about a linear evolution of artistic expression from simple to more complex. This idea has been discussed recently in light of new discoveries in the Rhone valley and the Swabian Jura. There is also the hypothesis that artistic expression developed during the Aurignacian to strengthen the social networks of the first modern human groups entering Europe. Here we present a unique piece of portable art found at an Aurignacian open-air site, Cantalouette II (Dordogne, France). The particular context of the finding, a flint workshop, the use of an up-to-now unknown engraving technique, the sunken relief, and the uncommon subject, a naturalistic and detailed bird, are evidence of the uniqueness of this piece of artwork, which sets it apart from the already-known Aurignacian artistic manifestations known from Western Europe. We take this uniqueness to represent an argument against the idea of a linear evolution of art. Also the particular context of this piece, immediately discarded after its production, shows that it was a sort of ephemeral artistic expression, a behavior as yet unknown for the Aurignacian. Moreover, the very fact that the context, technique, and subject of this art piece are previously unknown for the Aurignacian indicate that there was a higher degree of variability in Aurignacian artistic expressions than has been previously argued. This suggests that the search for a single explanation for the 'artistic explosion' observed in the Early Upper Paleolithic may be unfounded.