The Taphonomy of Senèze

Abstract

The later Villafranchian reference site of Senèze (Haute-Loire, France) has yielded not only valuable specimens of this period for taxonomic and paleobiological analyses, but also an interesting taphonomic problem. Several nearly complete or partial skeletons of fossil mammals have been found in anatomical position. In the first half of the twentieth century, thousands of fossils (including numerous partial skeletons) were exhumed through excavation over an extensive area of this paleo-lake. The high number of skeletons recovered from this maar suggested a catastrophic hypothesis about the site's origin. The survey and systematic excavations carried out from 2001 to 2006 by the Franco-American research team were focused on a more restricted area, providing more detailed information that makes possible a better interpretation of site formation at Senèze. A detailed taphonomic study has been undertaken to investigate this exceptional site. The analysis reported here is restricted to bone surface modifications of large-mammal fossils recovered from the systematic excavations. Some specimens from the older collections and mounted skeletons housed at the University Claude Bernard-Lyon 1 were also analyzed to confirm taphonomic modifications and pathologies. As a result of this taphonomic study of Senèze fossils, we demonstrate that carnivore activity has been mimicked by subaquatic compression marks and soil corrosion, and we establish criteria to distinguish each taphonomic agent. This investigation concludes that catastrophic events were not part of the principal taphonomic process at Senèze, nor was there any reworking (i.e., transportation or mixing of fossils from different time periods or environments). The fossil assemblage of Senèze is an accumulated association of animals (biocoenosis) that regularly visited the site in life to drink, where they eventually died and their carcasses were slowly buried, resting on the floor of the lake under water.