Sharovipteryx Perspective

I drew this a long time ago thinking up ideas for Sharovipteryx's peculiar leg-based patagia. There doesn't appear to be an arm-based patagium (and in fact there doesn't appear to be much of an arm compared to the leg) which got me thinking about similarly proportioned animals. Inspiration struck when I recalled Hesperornis and how the arms are so tiny they are effectively useless, whereas the limbs are used for aquatic propulsion, grebe and loon-style. The leg-based patagia then seem to remind me of aerofoils (or rather, hydrofoils). I've talked to aeronautic engineers, and this is at least plausible, but probably not effectively useful. There are only three reasons for this animal to be preserved in the deep-water environment it was, and these are 1) it was "flying" overhead and fell in -- this is the "pterosaur-ancestor" idea; 2) it was washed out to sea from land; 3) it was swimming and somehow died. I went with concept #3, here.