morphotype/flight adaptation of the same lineage, but how to get from something where the tail seems to play a major role in flight, long, bony and feathered as it was, to something where the tail's only significant role in flight *might* have been that of a vortex generator similar to its role in needletails today is beyond wht I'd want to imagine.
It's also not a given that Archie was capable of powered flight.
Ah, the eternal question... I'd put it "active" rather than "powered", because it was capable of a downstroke which near-certainly could generate significant lift. So there seems to have been a powered component to its flight, but how large that was is debatable.