Here are some possibilities and why they might have become extinct:
* You might be thinking of the White-footed Mouse (Peromyscus leucopus): This is a common rodent in North America, and they are not extinct.
* You might be thinking of a species that has gone extinct: There are many species of rodents that have gone extinct, often due to habitat loss, introduced predators, or disease.
To help you find the specific animal you're looking for, please provide:
* More details about the animal: Any other characteristics you remember, such as its size, color, habitat, etc.
* Where you heard or read about this animal: This could help narrow down the possibilities.
Once you provide more information, I can help you find the correct animal and its extinction status.