The Gastornis is depicted as a carnivorous predator. These days, experts believe that these birds were not carnivores, but herbivores or omnivores. They know this because its beak and claws are shaped differently than those pf predatory birds, and chemical analysis of its fossil bones have also shown traces of plant material.
Featured creatures: Leptictidium, Gastornis, Propalaeotherium, Godinotia, Ambulocetus, Formicium giganteum (giant ants), Mesonyx (small carnivore attacked by Ambulocetus). The book also features the early ratite Palaeotis.
The sound of Gastornis was a mix of a monkey and a rattlesnake, just like the Dilophosaurus from Jurassic Park (1993).
The sound of Leptictidium was a reversed and re-pitched recording of an otter.
The movements of Ambulocetus were based on those of an otter.