Dragon mount

Dear community
I just came back after many years and was going for the last quests of dawntrail when I saw someone riding a huge black dragon (or so it looked like)
I was doin some research and could not find anything
does anyone have any ideas on what could have been flying away from me?
looked like a black dragon or almost like a dinosaur haha
and no it is not midgardsormr

thanks in advance!