Any proavis as you would point out would have a fraction of that=20 range but doesn't make it any less viable. Predators like to stick around where the prey collects particularly if their range is restricted. W= aterhole anyone?? --dale (not a joke)
Well, if you drag Archie into it, both the anatomy and the size of that animal (or anything like it) make this scenario completely impossible as far as I can see. Do you postulate that the evolution of flight happened in much larger animals?