The mammals, inconspicuous during the dinosaur period, saw an increase in their size and number of species after the extinction of these giants sixty-five million years ago. This was the beginning of the Age of Mammals. But it was only at the beginning of the Eocene fifty-five million years ago during an extremely fast and intense global warming called PETM (Paleocene Eocene Thermal Maximum) when their diversity exploded. New groups then suddenly appeared on the three northern continents via intercontinental land bridges across which they made important dispersals. These new groups, called “modern mammals”, consist of rodents, lagomorphs, perissodactyls, artiodactyls, cetaceans, primates, carnivorans and bats. Although these eight groups represent 83 % of the extant mammal species diversity, their ancestors are still unknown. A short overview of the knowledge and recent progress on this research is here presented on the basis of Belgian studies and expeditions, especially in India and China.

Peer Review

Paper presented at the meeting of the Section of Natural and Medical Sciences held on 23 November 2010. Publication decision taken on 24 May 2011. Final text received on 17 June 2011.