<<David Peters wrote-
The smallest known pterosaurs, I remind you, are no smaller, nor in any parallel universe different than the smallest known adult birds and bats. They are volant from the time they leave the egg.
The smallest known adult birds are hummingbirds as far as I know, and those require at least 20 days or more before they are strong enough to fly. That's not 'volant from the time they leave the egg'.
Nick Gardner