The ruminants of Pech Desse and Pech du Fraysse (Quercy; MP28); evolution of the Oligocene ruminants of Europe

New material (both dental items and elements of the appendicular skeleton) belonging to the species Prodremotherium elongatum FILHOL, 1877; Dremotherium quercyi (FILHOL), 1887 and Dremotherium guthi JEHENNE, 1985, collected in the localities of Pech Desse and of Pech du Fraysse (Quercy Phosphorites), is described in this paper. The relative position of these localities attributed to the reference level MP28 is discussed. From our analysis and from recent works on the other genera of Oligocene ruminants of Europe, an appraisal of the geographical distribution of the species and the biostratigraphical extension of the different lineages is drawn up. The main episodes of the history of the group (migrations and extinctions) are related to the environmental changes at this period. Finally, a cladistic analysis with 18 characters was undertaken to attempt to specify the relationships between the 6 genera of ruminants here considered.