Birds are more optimized than bats in some niches (like long-distance flight), but vertebrate evolution is very stuck into path dependency, and they are way far from the optimum on the things that matter for most animals like maneuverability and acceleration.
Four-winged birds dying up can easily be a complete accident, even more because two-winged birds were almost completely killed once too.
Four-winged birds dying up can easily be a complete accident, even more because two-winged birds were almost completely killed once too.