Omnivorous dinosaurs include Anserimimus, Deinocheirus, Gallimimus and Othnielia. Fruitadens haagarorum was a small dinosaur known to be omnivorous by the presence of both sharp teeth resembling canines and leaf-shaped teeth suitable for grinding plants. As a heterdontosaurid, it exhibited a shift in diet from its earlier herbivorous relatives.
Several early maniraptor lines showed changes to an omnivorous diet. These included insect eaters such as alvarezsaurs, avialans and seedeaters, including some troodontids.
Ornithomimosaurs, also known as ostrich dinosaurs, lived in the Cretaceous Period and included Gallimimus, Shenzhousaurus and Ornithomimus. Some had teeth but most had beaks, long-clawed upper limbs and long legs with hooflike claws on the toes. Scientists believe that Ornithomimosaurs were among the fastest runners of all dinosaurs and ate a diet of plants and small animals.
Anserimimus was a fast-running ornithomimid with strong front limbs, and it lived in the Late Cretaceous period. It differed from related species due to its slightly curved claws and much stronger forelimbs. Gallimimus was its closest relative. Scientists hypothesize that ornithomimids, descended from carnivores, were actually omnivores or even herbivores. Gallimimus, which means rooster or chicken mimic, had hollow bones and the eyes on the sides of its head, similar to modern birds.