I am currently creating a small creature about the size of a squirrel. It lives in the trees and eats fruit. It is the prey of a cat-like creature that has a prehensile tail and is agile and can run quickly through the trees. Would a prehensile tail be useful for this creature? Or flaps of skin so it can glide? The only problem would be that they can make it harder for the creature to move around quickly and could get caught on branches. However, the decrease in mobility might be compensated for by the fact that the creature would be able to glide long distances. Is there a better option for the skin flaps because I don't think it needs a prehensile tail, which might be too clunky for such a small creature to benefit from.
Both prehensile tail and gliding!
Because you like them both and the combo is awesome. And it could work.
A gliding cat would have an attack something like a hawk, which could work. Cats can survive falling long distances because they are small and light and spread out in flight, increasing drag.
Like many small animals, cats are said to have a non-fatal terminal falling velocity. That is, because of their very low body volume-to-weight ratio these animals are able to slow their decent by spreading out ' flying squirrel style. Simply put, animals with these characteristics are fluffy and have a high drag coefficient giving them a greater chance of surviving these falls.
It helps to be fluffy too.
So my vision for your predatory arboreal cat. 1: It is smaller than its prey. That works fine for weasels who routinely take rats and birds three times their size.
2: It is very fluffy.
3: It has a long tail, clouded leopard style. The tail is fluffy and massive compared with the animal. It is used to balance in the trees like the clouded leopard does. It can be used to steer while "gliding" which is really a controlled long fall.
The tail is prehensile and here is where the prehensile tail comes in. Imagine you are a flying weasel who hits your prey at speed. You are both in a tree. What next? You both fall of the branch. An opossum-like prehensile tail lets your cat catch the branch and keep them both from falling while it has use of claws and teeth to dispatch the prey. The cats might also hang from their tails and drop onto prey below.
Pretty much this is a clouded leopard, smaller, flatter, fluffier and with a more fully prehensile tail.
A cat with a prehensile tail is the biggest stretch. Maybe this is a non-Carnivoran mammal or maybe something completely different. The wikipedia article has some interesting insights on why there are more animals with prehensile tails in the New World and more gliders in the Old World. https://en.wikipedia.org/wiki/Prehensile_tail