Huge versions of the ordinary aquatic mammal, often found in "lost world" areas
Giant beavers are huge versions of the ordinary aquatic mammal, often found in "lost world" areas. They are not normally aggressive but will defend their lairs, dams, and family with powerful bites from their 5 inch long incisors. They are surprisingly intelligent and will collect valuable items, though they rarely learn to use magic items of any sort.
Basic Fantasy Field Guide Omnibus