Fabrice Lihoreau

Whether bigger brains provide enhanced cognitive capacities is a long-lasting and controversial question. While big brains may not be required for producing sophisticated behavior, they could facilitate information processing and memory storage. Here, we report a positive relationship between head size and learning performance in two model bee species, using data from 2,141 individuals. Among honey bees, head size varied by about 30%, and those with larger heads showed higher olfactory learning performance for associative tasks that varied in difficulty. Microcomputed tomography measures indicated that this relationship was linked to brain size variation: The best odor learners had the largest antennal lobes. We made similar observations in bumblebees, suggesting that natural brain size variation is associated with individual cognitive variation in these social bees.

Révision des faunes de mammifères de la fin de l'Éocène inférieur de Mas de Gimel et de Naples (Montpellier, sud de la France) et description d'un nouveau rongeur théridomorphe. Les sites européens ayant livré des mammifères terrestres datés de la fin de l'Yprésien sont principalement localisés dans le Bassin de Paris. En Europe méridionale (France et Espagne), quelques localités sont également connues, mais toutes n'ont livré que des faunes pauvres, composées de seulement quelques taxons, à l'exception de la localité de Mas de Gimel (ville de Montpellier, Hérault, France), longtemps considérée comme la faune de référence de la fin de l'Yprésien en Europe méridionale. Curieusement, seuls les rongeurs, les artiodactyles et les métathériens de cette localité-clé ont été étudiés en détail depuis les années 1960. Sur la base de la collection originale conservée à l'Université de Montpellier, nous révisons l'ensemble des taxons de mammifères, ce qui nous amène à identifier 38 espèces parmi 12 ordres. Nous étudions également les localités voisines et contemporaines de Naples et Naples 2, où nous identifions 23 espèces parmi 10 ordres. Parmi les espèces identifiées dans les trois localités, nous décrivons le nouveau rongeur théridomorphe Hartenbergeromys pailladensis n. sp., caractérisé par de nombreuses crêtes fines et hautes sur les molaires supérieures et inférieures. Comparé aux quatre niveaux de référence MP (Mammal Paleogene) pour l'Éocène inférieur européen (MP7, MP8+9, MP10a et le possible ‘MP10b’), l’assemblage faunique de Mas de Gimel et de Naples est attribué au MP10a, et représente une référence européenne majeure pour cette période. Ce travail renforce l’hypothèse de l’homogénéité des faunes mammaliennes du Nord- et du Sud-Ouest européen durant l’Yprésien récent.

The Lophiodontidae are endemic perissodactyls from Europe that flourished during the Eocene. Despite their preponderance in the European fossil record, their exact origin and relationships within the perissodactyls remain unknown due to the rare and fragmentary material in the early Ypresian, the time of their earliest radiation. Lophiaspis maurettei is the oldest and earliest diverging lophiodontid known to date but is unfortunately poorly known. We describe here the results of new excavations of the type locality of Palette. Important new material including complete skulls, mandibles, post-cranial elements and juvenile specimens lead us to revise Lophiaspis maurettei from Palette and other localities and to describe novel morphology for this species. According to an original phylogenetic analysis, based on a revised matrix of dental, cranio-mandibular and postcranial characters, Ls. maurettei is an early diverging lophiodontid morphologically close to Protomoropus and Paleomoropus, two basal chalicotheres, known from Asia and North America, respectively. Our resulting topology does not support the previously proposed inclusion of the lophiodontids within the Ceratomorpha and supports a position within the suborder Ancylopoda, close to some Eomoropidae representatives. These results imply that Ls. maurettei was restricted to Southern Europe during the early Eocene, which would be compatible with an Asian origin for lophiodontids in accordance with the evolutionary history of other perissodactyls and placental mammals.

The fossiliferous localities of Aumelas and Saint-Martin-de-Londres in the Montpellier limestones (Hérault, France), known since the 1960s and 1980s, were originally dated as late middle Eocene (Lutetian), close to the European Mammal Palaeogene Reference Level 13 (MP13). This period is a key time interval in the initial radiation of European endemic mammals. We present here a systematic revision of the artiodactyl fauna from Aumelas and Saint-Martin-de-Londres in order to propose a biochronological revision of these localities. We identified five artiodactyl species: Aumelasia gabineaudi, Dichobune aff. robertiana, Eurodexis cf. russelli, Eurodexeinae indet. and Lophiobunodon minervoisensis. Two of these species are known in both localities. Comparisons with other European localities support an earlier dating than late middle Eocene for Aumelas and Saint-Martin-de-Londres. These localities seem to be close to the Ypresian/Lutetian boundary and could constitute a rare record of this period in Europe. The age of these localities is critical for discussing the initial radiations of endemic European artiodactyl families (Cebochoeridae, Choeropotamidae, Mixtotheriidae, Anoplotheriidae, Xiphodontidae, Cainotheriidae and Amphimerycidae). This systematic revision allows us to test the validity of phylogenetic relationships between these families using cladistic analyses. Our results question the monophyly of Dichobunidae and Choeropotamidae but support the older concept of Haplobunodontidae. This study, which constitutes a first step towards a better understanding of their evolutionary history, suggests that the European artiodactyl radiation took place close to the Ypresian/Lutetian boundary.