Not directly. There was one or more intermediary stage, probably jumping between trees. Outside my window, the squirrels are busy doing just that.

I have a vague recollection of reading that most squirrels have evidence of trauma from falling, such as healed bone fractures.

Flying squirrels show an intermediate stage of such an evolution process. Evolution always involves intermediate stages. Even if a large discrete change could occur, fine tuning it is an extended incremental process.

If you go to the Cornell Ornithology Lab feeder cam and scan through the feed at night, you will find flying squirrels at the feeder. They show signs of nocturnal adaptation, another connection to bats.

https://www.youtube.com/watch?v=N609loYkFJo

The grey squirrels in my UK garden routinely make what we call the 'leap of death' between two trees whose upper branches are a few feet apart, at different heights. I've seen two falls - one because the target branch snapped when the squirrel landed, the other during a high-speed chase where one of the squirrels apparently mis-jumped. In both cases the squirrels fell into lower level bushes and disappeared (no subsequent bodies). It's not unusual to see a squirrel with one one useless leg but still managing to feed and get around, so I can quite believe that they can recover from a broken limb given sufficient time.

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We also had a pheasant who routinely visited the garden and one day showed up with a broken leg, that survived for ages before eventually disappearing. Initially he sat quietly in the undergrowth but started hopping around and doing short flights (with clumsy landings). I put out bird seed for him and he incredibly quickly learned to hoot and flap outside my back door when he was hungry. He once followed me into my shed when he was expecting feeding and had to be shoo'd out.