I take it you are a firm believer in cryptids ;-)
Indeed. I think the hypothesis behind these sightings is that maybe another dimensions/timelines that are parallel to our are somehow interacting for briefs periods of time.You might find this interesting:
U.S.A. Sightings | Live Pterosaur
www.livepterosaur.com
I don't know...Find it hard to believe that something that large could still be flying in our skies... And eyewitness accounts I do not put much faith in....