Gallimimus was an ornithomimid that lived in the late Cretaceous in Mongolia. With individuals as long as 26 ft, they were the largest confirmed ornithomimid  until the discovery of the full body of Deinocheirus, proving that it is an ornithomimid.
Gallimimus was ostrich-like, with a small head, toothless beak, large eyes, a long neck, short arms, long legs, and a long tail. It had a short 'hand' relative to the humerus length, when compared to other ornithomimids. The tail was used for balance. The eyes were placed on the sides of its head and the bottom front part of its beak was shaped like a shovel. Like most modern birds and other theropods, it had hollow bones. Gallimimus had a lot of traits that hint that it could run fast, such as a strong ilium, heavy tail base, long limbs, a long tibia and metatarsus and short toes, but no one knows how fast it could run.
Gallimimus in The Land Before Time
They appear in several The Land Before Time movies as Rainbow Faces, so called due to their striped beaks (Even though they refer to actual rainbows as "Sky Colors"). They first appear in The Land Before Time VII: The Stone of Cold Fire, although the ones seen were implied to be supernatural beings in disguise, most likely extraterrestrial aliens. These two were also the only ones with large roles. Since then, real Gallimimus have appeared in The Land Before Time IX: Journey to Big Water, The Land Before Time X: The Great Longneck Migration, and The Land Before Time XI: Invasion of the Tinysauruses.
- Barrett, P. M. (2005). "The diet of ostrich dinosaurs (Theropoda: Ornithomimosauria)." Palaeontology, 48: 347-358.
- Hurum, J. 2001. Lower jaw of Gallimimus bullatus. pp. 34–41. In: Mesozoic Vertebrate Life. Ed.s Tanke, D. H., Carpenter, K., Skrepnick, M. W. Indiana University Press.
- Kobayashi, Y. and Barsbold, R. (2006). "Ornithomimids from the Nemegt Formation of Mongolia." Journal of the Paleontological Society of Korea, 22(1): 195-207.
- Norell, M. A., Makovicky, P., and Currie, P. J. (2001). "The beaks of ostrich dinosaurs." Nature, 412: 873-874.
- Peter J. Makovicky, Daqing Li, Ke-Qin Gao, Matthew Lewin, Gregory M. Erickson & Mark A. Norell. (2009). "A giant ornithomimosaur from the Early Cretaceous of China". Proceedings of the Royal Society B: Biological Sciences, 277(1679): 211-217. doi: 10.1098/rspb.2009.0236
- Paul, Gregory S. (1988). Predatory Dinosaurs of the World. New York: Simon & Schuster. p. 393. ISBN 0-671-61946-2.