I was going to say and then read your last paragraph, Horner isn't reproducing any particular dino, just funnin' for science.
We could start with Seriema and breed for size, there's another decendant species too, but I forget. Maybe the Secretary Bird?
Speaking of ground hawks, have you seen...
I don't think that's one of his, but that is the Parrot Beak Asil. There's no Western standard of perfection for the Parrot Beak and I don't know of an Eastern standard.
Though... if I were judging I would say - no gap - should be present / showing when the bird closes its beak; and their beak...