[UCANSEE2]

It’s a presumption or a guess.

20 foot wingspan. Found in ancient seabed. Teeth of a carnivore. Most of the surface of the Earth is ocean. Most birds fly over water and many of them snatch fish from the water.

What would be your guess that it ate ?

[RegulatorCountry]

I would say that it’s reasonably certain to have been a carnivore. Beyond that is guesswork.

[The Cajun]

What would be your guess that it ate ?

With those teeth, don't think it ate fruit or sucked nectar out of flowers............Just guessing :)

[EinNYC]

With a 20 foot wingspan, the bird would not have been highly agile, able to turn on a dime like today's modern hawks. It would have been mostly a glider, like today's albatrosses. It probably had to dive from cliffs to get airborne with a wingspan like that. These characteristics would pretty much dictate it was a fish nabber.