Ornithomimosaurs (meaning 'bird mimic lizards') or members of the clade Ornithomimosauria are theropod dinosaurs, like Gallimimus, which bore a superficial resemblance to modern ostriches. They were fast, fleet-footed, omnivorous or herbivorous dinosaurs from the Upper Cretaceous Period of Laurasia (now Asia, Europe and North America). The skull, sitting atop a long neck, was relatively small, with large eyes. Some primitive species had teeth but most had toothless beaks.