Gastornis was a large predatory bird that lived 49 million years ago in Europe. They were similar in shape and size to, but not directly related to the American Terror Birds.
Andy followed a Gastornis to its nest and shrunk down using the Gizmo so he could get a good look at the egg. The Gastornis returned and Andy hid behind the egg. The chick started hatching and Andy took a piece of egg shell but he had to lure some Giant Ants away, saving the Gastornis chick. (APA: Gastornis and Egg)