IntroductionThe Gallimimus was a dinosaur that existed on the earth about 71 to 68 million years ago. This time period lies in the Maastrichtian age of the Cretaceous Period of the Mesozoic Era. This age was the last phase of the Cretaceous, at the end of which all the dinosaurs became extinct. So it is quite possible that it lived right up till the Cretaceous Paleogene extinction event.
The remains of this reptile were discovered in Mongolia, Asia. As Mongolia lies on border of Asia and Europe, it is possible that its reach extended towards Europe as well. This dinosaur became well known after it was showcased in the movie Jurassic Park. It was chased and devoured by a Tyrannosaurus. The T. rex was a North American dinosaur while the Gallimimus was Asian. But many such creative liberties were taken in the movie so this discrepancy can be ignored. Moreover, the tyrannosaur Tarbosaurus was indeed present in Mongolia during the same time as the Gallimimus, so it being hunted by tyannosaurid theropods is a probable scenario.
This animal belonged to the ornithomimid group of dinosaurs and was one of the largest in that taxon at a length of 25 meters. Its weight is calculated to be about 400 to 800 kilos.
The name Gallimimus is a combination of two words. The term 'gallus' is the Latin word for 'rooster' or 'chicken'. 'Gallus' is also the generic name for fowls and chicken. The suffix 'mimus' is derived from the word 'mimic'. Thus, the name Gallimimus roughly translates to 'resembling or mimicking a chicken'. Its cervical vertebrae resembles those of the Galliformes birds. In fact the family name Ornithomimidae also means 'resembling a bird'. But this dinosaur was much larger than a chicken. It could be comparable to an ostrich.
The type species of this genus is the G. bullatus. This name is inspired from the Roman amulet 'bulla', which was given to male children a few days after their birth. It alludes to the distinct swelling that the Gallimimus showed underneath its cranium at the parasphenoid bone.
The christening of these remains was performed by scientists Barsbold, Osmolska and Roniewicz in 1972.
Discovery of fossils
The holotype of the Gallimimus was discovered in a joint Polish and Mongolian excavation expedition. It was headed by paleontologist Zofia Kielan Jawarowska. They were found in the Tsagan Khushu region of the Gobi desert in 1963. They were described almost a year later in 1972.
The holotype comprised of an almost complete skull with a partial post cranial skeleton.
Subsequently, many other individual skeleton belonging to both adult and juvenile specimen were discovered from the Gobi desert.
In the year 1996, Barsbold reported a second sub species belonging to the Gallimimus tha was discovered in the Bayan Sireh Formation in Burkhant, Mongolia. He named it the G. mongolensis. But upon further research, he found that the fossils were markedly different from the Gallimimus and so he later deemed them to belong to an undescribed ornithomimid.
The structure of the skull and beak
The skull of the Gallimimus has been well described. The orbits of the skull were located on the sides, which prevented the dinosaur having a stereoscopic vision. The most prominent and distinctive feature of the skull was the snout, which was modified to form a beak. The beak was made up of fibrous tissue and lacked teeth. The structure of the beak resembled that of modern day ducks. It had projections on the maxilla which could have been used to sift through marshy soil to search for food. The joint between the maxilla and mandible was quite stiff, which restricted the movement of the beak.
The Gallimimus is classified under suborder Theropoda, clade Ornithomimosauria, family Ornithomimosauridae and super family Ornithomimosaurinae. The ornithomimosaurids externally resemble present day ostriches. They hold the distinction of being herbivorous or omnivorous where most theropods carnivorous.
The Gallimimus was a reasonably large dinosaurs. It grew to an adult length of 8.5 meters. Its weight however was proportionately modest at 100p to 1500 pounds.
Its beak was keratinous and resembled that of modern ducks.
The forelegs of the dinosaur bore three long fingers with thick claws.
It is yet unknown if the Gallimimus possessed feathers. Considering the fact that most ornithomimosaurs were indeed feathered, scientists speculate that this reptile was too.
The hind legs of this dinosaur were superbly adapted for sprinting. Its tibia was substantially longer than in its femur, allowing it to accelerate very fast.
The tail of the Gallimimus was long, thick at the base and slender towards the apex.
Habits and habitat
The Gallimimus was a bipedal dinosaur. It was obviously terrestrial, even if it did possess feathers.
The feeding habits of the reptile are still a matter of contention. Considering its beak had no teeth, it could not have ripped or torn its prey. It could at best have impaled smaller reptiles or thrown them against hard surfaces. The beak could also have been used to sift through marshes to capture frogs and fish. Its long claws could have been used to grasp eggs and the beak would have broken them.
However, based on the size of the dinosaur, obtaining enough energy through eating smaller animals seems unlikely. It more likely used its digits to forage shrubs and bushes while its beak could cut through them.
Furthermore, the wide set eyes could detect threats easily, but may not have been sensitive enough to allowing good hunting skills. But it is not impossible to hunt with such an eye structure. Although a diet consisting of plants is most likely, omnivorous habits cannot be ruled out. The habitat of the Gallimimus consisted of lakes and rivers and marshes, with a lot of green vegetation. This is in stark contrast with the current condition of the Gobi Desert.
Related and coexisting species
The Gallimimus was amongst the evolved ornithomimids and was related to the Sinornithomimus, Anserimimus and the Quipalong. It most likely shares its environment with the Tarbosaurus and the Therizinosaurus.
The final notes
The Gallimimus was a well evolved, plant eating theropod. This transition to herbivory possible made in response to the newer variety of flowering plants that became available in the late Cretaceous. Many of its habits are not understood well even today. Until more diagnostically relevant fossils are discovered, the Gallimimus will continue to be an enigma.
Just for fun we have a soundclip available for you to hear what a Gallimimus could've sounded like. Click to the Dinosaur Sounds area to hear it. Please note that the dinosaur sounds are only for entertainment and are not an actual fact.