My guess is they taste like chicken. After all, birds evolved from dinosaurs, and things like frog legs taste like chicken.
Ostrich also evolved from the dinosaurs and has its own unique taste. I bet it varied though probably the range of bird meat tastes is a good place to put our first guesses.
No need to wonder, just go sample some birds.
More to the intent of the question, maybe the more reptilian, ancient ones tasted closer to crocodiles.