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

Emmanuel Gheerbrant,Dominique Teodori

doi:10.5852/cr-palevol2021v20a13

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.

Highlights

Mammals from the Latest Cretaceous remain poorly known, and have a very heterogeneous geographical fossil record
The Late Cretaceous European eutherian mammals are only documented by isolated teeth and a few partial jaws from eight localities found in Southern France, Spain, and Portugal, which were part of the Ibero-Armorican Island in the European Archipelago
Azilestes n. gen. shows remarkable specialized features that are unknown in Cretaceous eutherians, but are instead known in some herbivorous crown placental clades from the Cenozoic

Summary

Introduction

Mammals from the Latest Cretaceous remain poorly known, and have a very heterogeneous geographical fossil record. We report the discovery of a damaged dentary belonging to a new mammal from a vertebrate-bearing level of the Grès de Labarre Formation in the Plantaurel massif of northern Pyrenees, near the Mas-d’Azil (Ariège Department, SW France) (Fig. 1). The vertebrate-bearing level is a fossiliferous hard sandstone (Fig. 2). It belongs to the upper unit of the Grès de Labarre which overlies the Marnes d’En Gauly. The Grès de Labarre Fm, together with the overlying “Marnes Rouges Inférieures” Fm (an eastern lateral equivalent of the Marnes d’Auzas Fm), comprises the last Cretaceous deposits of the Sub-Pyrenean zone in the Plantaurel massif

Methods

Findings

Discussion

Conclusion