What is the defining dental feature classifying flying squirrels within Rodentia?

Answer

A single pair of continuously growing incisors.

The signature characteristic of all true rodents, including flying squirrels, is possessing a single pair of continuously growing, chisel-like upper incisors and a single pair of lower incisors that must be worn down by gnawing.

What is the defining dental feature classifying flying squirrels within Rodentia?
animalmammalclassificationrodentsquirrel