An enigmatic specialized new eutherian mammal from the Late Cretaceous of Western Europe (Northern Pyrenees)

Abstract

We report the discovery of a new Late Cretaceous eutherian mammal, Azilestes ragei n. gen., n. sp. from the Mas-d’Azil northern Pyrenean site (France), which is among the largest known. It is only known from a broken lower jaw found in uppermost levels of the Grès de Labarre Formation (early Maastrichtian). Despite its poor preservation, it displays distinctive specialized features with respect to known Cretaceous eutherians. This includes a reduced premolar formula and shortened and robust jaw, an incipient hypolophid, and a cingular-like postcristid and hypoconulid. The phylogenetic analysis suggests indeed a possible stem relationship between Azilestes n. gen. and some clades of herbivorous Cenozoic placentals, but with weak support. Several molar features reminiscent of the Zhelestidae, especially Valentinella Tabuce, Vianey-Liaud & Garcia, 2004, support instead that Azilestes n. gen. is a basal eutherian showing early specialization in a herbivorous diet convergent with some crown placentals. Whatever the suprageneric position of Azilestes n. gen., which remains to be clarified with additional material, its discovery highlights a significant diversity of European Cretaceous eutherians in contrast to their very poor fossil record.