One of the most remarkable finds in the clay layers of Tegelen are two species: the modern European beaver and the extinct Tegelen beaver. The fossil teeth found indicate that the Tegelen beaver, in contrast to the European beaver, ate only the soft stems of plants. As the climate changed at the end of the Tiglian and temperatures dropped considerably, the vegetation changed, which meant that there was no food left for the Tegelen beaver. Eventually this led to the demise of the species.