|Name: La Voulte-sur-Rhône
Location: Ardèche, France
Age: Lower Callovian, Jurassic
The fauna is divided into two very distinct faunas, allochthonous and in situ.
The allochthonous fauna mainly consists of soft-bodied organisms which lived on the sea floor (benthic) or swam freely just above it (nektobenthic). It includes
The in situ mortality horizon consists of abundant pavements of a bivalve, Bositra buchi. It is likely to have been pelagic (lived in the open ocean) and the pavement was produced as they fell to bottom of the sea when they died. This was probably a result of anoxia (a severe reduction in the amount of oxygen dissolved in the water). The valves of their shells are still articulated (joined together) and spread open like wings.
Trace fossils of in situ horizontal burrows are another indication of the presence of a local infauna (organisms which lived in the sediment).