Gastornis, also known as Diatryma, was a prehistoric neognath bird. It was smaller and more robust than the terror bird featured in Sabre Tooth; it lived 56-41 MYA, during the Paleocene and the early Eocene. Strangely, it's been questioned whether this animal was a herbivore or a carnivore or even an omnivore. In 2014, The body structure of gastornis fossils led scientists to classify gastornis as a herbivorous animal.