Gallimimus

About Gallimimus

Characteristics: The Largest "Ostrich Dinosaur" that Ran Through the Cretaceous

Gallimimus had one of the largest physiques among the ornithomimosaurs, the so-called "ostrich dinosaurs".

Despite its massive body, its skeleton was extremely lightweight and highly pneumatized, making it one of the fastest land animals in the Cretaceous, capable of running at speeds of about 42 to 60 km/h. Its feet had a special structure called an "arctometatarsal" that effectively dispersed the impact of running.

Compared to its huge body, its head was very small and had a toothless beak. It also had large eyes on the sides of its head, ensuring a wide field of vision to quickly detect approaching carnivorous dinosaurs (such as Tarbosaurus) from behind or the sides.

Diet and Herd Life

What the toothless Gallimimus ate has long been debated.

Previously, based on structures inside its beak, it was thought to be a "filter feeder" that strained microorganisms and plankton from the water. However, the current leading theory is that it was an "omnivore focused on plants," using its strong beak to crop tough vegetation and a huge digestive tract to digest it slowly. It is thought to have occasionally preyed on insects and small animals like lizards.

In addition, since individuals of various growth stages have been found together in the same location, it is known that Gallimimus possessed high sociality and lived in herds. When attacked by enemies, the entire herd would flee simultaneously to prevent predators from narrowing down their targets. Changes in body proportions with growth have also been confirmed; juveniles had large eyes and short snouts, while the beak lengthened as they grew.

The Mystery of Feathers and Forelimbs

Influenced by movies and other media, Gallimimus was often depicted covered in scales for many years. However, recent research has found traces of feathers on its close relative Ornithomimus, making it highly probable that Gallimimus was also entirely covered in feathers. In particular, it is thought that the forelimbs of fully grown adults had "wings"—not for flying, but for courtship displays or brooding eggs.

The forelimbs themselves were generally short, and the wrist joints were relatively fixed. Therefore, actions like turning the palms inward to "grasp" objects were impossible. Rather than weapons, the forelimbs were likely used for tasks such as pulling plant branches closer or scratching the ground to search for food.

Discovery, Classification, and Contribution to Visual Technology

Fossils of Gallimimus were discovered by the joint Polish-Mongolian Gobi Desert expeditions that began in 1963. This project saw multiple female researchers (like Zofia Kielan-Jaworowska) play leading roles. In 1972, in collaboration with Mongolian paleontologist Rinchen Barsbold, a new genus and species, "Gallimimus bullatus," was described based on specimen number IGM 100/11. Specimen IGM 100/11 consists of a nearly complete skeleton including a distorted snout, incomplete lower jaw, vertebral series, and pelvis.
For a time, its classification shifted back and forth; it was lumped into the same "Ornithomimus" genus as the North American dinosaur due to similar skull shapes, or classified in its own group alongside the troodontids. However, subsequent detailed studies confirmed clear differences in snout shape and limb proportions, firmly establishing it today as the independent genus "Gallimimus."

Gallimimus is also a dinosaur that revolutionized the history of film. In the 1993 movie "Jurassic Park," the scene of a herd of Gallimimus sprinting across a sunlit plain was the first full-scale computer graphics (CGI) action scene of a living creature in cinematic history. Thanks to this technological breakthrough, the mainstream of special effects completely shifted from stop-motion to CG, laying the foundation for today's visual effects technology.

Gallimimus Stamp and Fossil Gallery