Gallimimus

Gallimimus bullatus is the largest and most well-documented member of Ornithomimidae. These "ostrich mimics" are known for their long necks, small toothless heads, and slender limbs. They bear a strong resemblance to modern ratite birds like ostriches and emus but on a much larger scale. The name Gallimimus means "chicken mimic," a nod to its bird-like neck vertebrae, while bullatus refers to a bulbous structure at the base of its skull.

The animal reached lengths of about 6 m, with much of that consisting of its neck and tail. It weighed approximately 440 kg. Its leg proportions, with lower legs longer than the thighs, indicate it was built for speed. Its small skull featured a broad, toothless beak. The forelimbs ended in three-fingered hands with short, straight claws, which were quite different from the curved claws of dromaeosaurids. Microscopic analysis of its beak (Norell et al. 2001) revealed grooves that suggest a filter-feeding capability. These keratinous structures may have functioned like the combs found in modern ducks.

As members of the coelurosaur group, ornithomimosaurs were almost certainly feathered. Evidence from relatives like Ornithomimus and Pelecanimimus shows they possessed fluffy proto-feathers on their bodies and specialized display feathers on their arms.

Gallimimus shared the Nemegt Formation with predators like Tarbosaurus and other unique dinosaurs such as Therizinosaurus and Saurolophus. The environment was a wet floodplain characterized by rivers and pools, which fits well with the theory that Gallimimus was a filter-feeder. Although direct evidence from stomach contents is lacking, the structure of its beak suggest it likely consumed small invertebrates and plants from the water.

Based on its hindlimb anatomy and biomechanical models, Gallimimus was likely one of the fastest dinosaurs for its size. Researchers estimate it could sustain speeds of 50–60 km/h, similar to a modern ostrich.

• GIN 100/11 — holotype, ~75% complete adult, Polish-Mongolian Geological Institute, Warsaw.
• GIN 100/12, 100/13 — referred adults and juveniles.
• Additional Nemegt specimens at the Mongolian Palaeontological Centre.

Filter-feeding — the keratinous comb interpretation (Norell et al. 2001) is broadly supported but the precise feeding behaviour is hard to test. Phylogenetic position within Ornithomimidae — well-resolved as a derived ornithomimid. Sociality — multiple individuals at single sites suggest possible herd or aggregation behaviour, but evidence is not conclusive.

Gallimimus is one of the most recognisable Late Cretaceous dinosaurs because of its high-profile cameo in Jurassic Park (1993) — the "they're flocking this way" stampede scene. Prehistoric Planet (2022) presents it accurately as a feathered, possibly filter-feeding generalist.

• theropoda
• oviraptor
• troodon

• Osmólska, H., Roniewicz, E., & Barsbold, R. (1972). A new dinosaur, Gallimimus bullatus, n. gen., n. sp. (Ornithomimidae) from the Upper Cretaceous of Mongolia. Palaeontologia Polonica, 27, 103–143.
• Norell, M. A., Makovicky, P. J., & Currie, P. J. (2001). The beaks of ostrich dinosaurs. Nature, 412, 873–874.
• Makovicky, P. J., Kobayashi, Y., & Currie, P. J. (2004). Ornithomimosauria. In The Dinosauria (2nd ed.).
• Cuesta, E., et al. (2015). Pectoral girdle and forelimb anatomy of Concavenator corcovatus. PLOS ONE, 10, e0123094.