Both squirrels and bats have been around for over 35 million years with bat-like flying mammals appearing approximately 15 million years before squirrels in the fossil records.
Both species evolved from just one part of ancient North America and spread to nearly all parts of the world. Bats and flying squirrels have some common characteristics with both being creatures of the night, eating many of the same foods and having the ability to soar through the air.
Both species also emit high pitched vocalizations and have been known to take up residences in the same areas, such as attics. Bats and flying squirrels also have some minor physical resemblances that can lead people to believe the two animals may be related.
So, with all these seeming similarities it raises the question, “Are flying squirrels and bats related?”
The quick answer is that flying squirrels and bats are related at the level of Class (Mammals) but are not related at the level of Order as flying squirrels are Rodents and bats are Chiroptera.