Meta guess; In the movie, Alex was meant to talk from the startThe bird is clearly the only major character with a clear cut "personality", even if you remove the dialogue, and his voice matches up best with his mannerisms without detracting from the story—it seems likely that the writers wanted Alex to be the only talking dinosaur at first, but then changed it so that all of the main ones talk.
Baryonyx in the original showWord of God is that Baryonyx was going to appear in "Giant of the Skies", but was cut. Baryonyx was discovered in England, the implied first European stop of the Ornithocheirus in its migration to Spain. This segment is notorious for the misplaced appearance of American Utahraptor, which has led some to assume that Utahraptor replaced Baryonyx in this segment during production. Well, in 1997, when the show was beginning production, a Baryonyx was discovered with fish scales and remains of a young Iguanodon in its gut. And what happens in this segment in the episode? The Ornithocheirus steals fish from a smaller pterosaur, and then watches a Utahraptor pack hunt an Iguanodon. This is the guess: In the original script featuring Baryonyx rather than Utahraptor, Ornithocheirus would steal fish from Baryonyx, and then Baryonyx, being still hungry, would turn to the Iguanodon herd and kill a youngster.