Alexornis is one of the oldest flying birds. It is however still too small to compete with the giant pterosaurs of his time. Like the yellow-billed oxpecker birds on the buffalo, the dinosaur Alexornis lives in symbiosis beside the great herbivorous dinosaurs (Ex: ceratopsians). The large herbivore provide protection against predators while the Alexornis cleans them by eating the unwanted insects, parasites and the remnants of their meals.