This resulted in drier and more open habitats dominating the early Oligocene, and the loss of the dense forests that characterised the Eocene epoch. This environmental change, coupled with the arrival of new and better-adapted mammalian groups from Asia, triggered a decline in endemic European mammal groups such as Palaeotheriidae and Anoplotheriidae.
The shift towards drier and more open habitats during the early Oligocene had significant consequences. The loss of dense forests typical of the Eocene epoch was accompanied by the arrival of new and better-adapted mammalian species from Asia, which in turn led to a decline among European endemic mammal groups such as Palaeotheriidae and Anoplotheriidae.