Taeniodont

Taeniodonta ("banded teeth") is an extinct early group of cimolestid mammals known from the Palaeocene to the Eocene. Taeniodonts evolved quickly into highly specialized digging animals, and varied greatly in size, from rat-sized to species as large as a bear. Later species developed prominent front teeth and huge claws for digging and rooting. Some genera, like Stylinodon, had ever-growing teeth.