Gallimimus

Gallimimus Temporal range: Late Cretaceous,
Mounted skeleton, Natural History Museum, London
Scientific classification
Missing taxonomy template (fix):	Gallimimus bullatus

Gallimimus (Template:PronEng GAL-i-MYE-mus) (meaning "chicken or rooster mimic") is a genus of ornithomimid dinosaur from the late Cretaceous period (Maastrichtian stage) Nemegt Formation of Mongolia. With individuals as long as 8 metres (26 ft), it was one of the largest ornithomimosaurs. Gallimimus is known from multiple individuals, ranging from juvenile (about 0.5 metres tall at the hip) to adult (about 2 metres tall at the hip).

Feathered Gallimimus.

A juvenile Gallimimus bullatus skull.

The fossil remains of this dinosaur were discovered in the early 1970s in the Gobi Desert of Mongolia. In 1972, it was named by paleontologists Rinchen Barsbold, Halszka Osmólska, and Ewa Roniewicz. The only known species is Gallimimus bullatus. A supposed second species, "Gallimimus mongoliensis", has never been formally referred to this genus. A recent reanalysis of the nearly complete skeleton of Gallimimus mongoliensis concluded that it is not a species of Gallimimus but may represent a new, currently unnamed ornithomimid genus.

Description

Gallimimus was rather ostrich-like, with a small head, large eyes, a long neck, short arms, long legs, and a long tail. A diagnostic character of Gallimimus is a distinctly short 'hand' relative to the humerus length, when compared to other ornithomimids. The tail was used as a counter-balance. The eyes were located on the sides of its head, meaning that it did not possess binocular vision. Like most modern birds, it had hollow bones. Gallimimus had a number of adaptations which suggest good running ability, such as long limbs, a long tibia and metatarsus and short toes, but it is unknown how fast it could run.

Beak and Paleoecology

The feeding habits of ornithomimids have been controversial.

In 2001 Norell et al. reported a specimen of Gallimimus (IGM 100/1133): a skull with soft tissue preservation. This specimen, as well as another new fossil skull of Ornithomimus, had a keratinous beak with vertical grooves projecting from the bony upper mandible. These structures are reminiscent of the lamellae seen in ducks, in which they function to strain small edible items like plants, forams, mollusks, and ostracods from the water. The authors further noted that ornithomimids were abundant in mesic environments, and rarer in more arid environments, suggesting that they may have depended on waterborne sources of food, possibly filter feeding. They noted that primitive ornithomimids had well developed teeth, while derived forms were edentulous and probably could not feed on large animals.

One later paper questioned the conclusions of Norell et al. Barrett (2005) noted that vertical ridges are seen on the inner surface of the beaks of strictly herbivorous turtles, and also the hadrosaurid Edmontosaurus. Barrett also offered calculations, estimating how much energy could be derived from filter feeding and the probable energy needs of an animal as big as Gallimimus. He concluded that herbivory was more likely.

In popular culture

Gallimimus bullatus skeleton cast, Poland

Gallimimus appeared in the motion picture Jurassic Park. A flock was seen running across a vast field from a Tyrannosaurus, which attacked and killed one of the ornithomimids. Gallimimus is also featured in the film's first sequel, The Lost World: Jurassic Park, during the 'roundup' sequence.