Why are we surrounded by only one group of placental carnivorous mammals (Carnivora: the present-day lions, dogs, bears, and seals among others) today, while at least three other groups of placental mammals (Hyaenodonta, Mesonychia, Oxyaenidae) were in competition with carnivorans 50 million years ago?
These four mammalian groups share an important feature: the presence of specialized teeth that are devoted to cut meat, the carnassial teeth.Traditionally, the presence/absence as well as the position of carnassial teeth have been considered as crucial features for discriminating the carnivorous mammal groups.
Since the 1990’s, palaeontologists have investigated the success of carnivorans and their crucial adaptations in detail.It appeared that carnivorans have outcompeted hyaenodonts, mesonychids, and oxyaenids during the Eocene, specifically from around 50 Myr when carnivorans began to dominate and to diversify. Studies of the ecomorphology of these taxa revealed that carnivorans may have been successful due to the anterior position of the carnassial teeth compared to the other placental carnivorous mammals. It has been indeed suggested, based on the North American fossil record, that the evolutionary success of carnivorans may have resulted from the broad range of dental adaptations (i.e. a broad variety of diets) conferred by this particular position of their carnassial teeth.
Hypothetically, palaeontologists proposed that the study of the European, Asian, and African carnivourous mammals would reveal the generality of patterns observed in North America.
In order to test this hypothesis, we have analysed the species richness of the European carnivorous mammals during the Paleogene. Surprisingly, our initial survey suggests that the results of this competition were diametrically opposed in North America and Europe: carnivorans were not as taxonomically successful in Europe during the Eocene.
The present project proposes to document the evolutionary history of the ecology of carnivorous mammals that lived on our continent during the Paleogene (66-23 Myr). We hypothesize that an analysis of the ecomorphology of these carnivorous mammals will allow for a clearer understanding of the causes that could explain the greater success of hyaenodonts in Europe compared to North America.
