Got me reading up on Carnivora. Interesting, I never knew that walruses and seals are so closely related to canines and felines! Then again, I never studied biology, so there are no doubt plenty more similarly well-known fauna family ties that I never learned about.
Anyone who has met a sea lion up close knows that the name 'sea dog' was wasted on sharks. An error which has been corrected in the mascot of a few minor sports clubs.
They're not big cats, they're only feliforms. Big cats belong to felidae. But no, it's not commonly known that hyenas are more closely related to cats than to dogs.
