Gallimimus (/ˌɡælɪˈmaɪməs/ GAL-i-MY-məs) is a genus of theropod dinosaur that lived in what is now Mongolia during the Late Cretaceous period, about seventy million years ago (mya). Several fossils in various stages of growth were discovered by Polish-Mongolian expeditions in the Gobi Desert of Mongolia during the 1960s; a large skeleton discovered in this region was made the holotype specimen of the new genus and species Gallimimus bullatus in 1972. The generic name means "chicken mimic", referring to the similarities between its neck vertebrae and those of the Galliformes. The specific name is derived from bulla, a gold capsule worn by Roman youth, in reference to a bulbous structure at the base of the skull of Gallimimus. At the time it was named, the fossils of Gallimimus represented the most complete and best preserved ornithomimid ("ostrich dinosaur") material yet discovered, and the genus remains one of the best known members of the group.
Gallimimus is the largest known ornithomimid; adults were about 6 metres (20 ft) long, 1.9 metres (6 ft 3 in) tall at the hip and weighed about 440 kilograms (970 lb). As evidenced by its relative Ornithomimus, it would have had feathers. The head was small and light with large eyes that faced to the sides. The snout was long compared to other ornithomimids, although it was broader and more rounded at the tip than in other species. Gallimimus was toothless with a keratinous (horny) beak, and had a delicate lower jaw. Many of the vertebrae had openings that indicate they were pneumatic (air-filled). The neck was proportionally long in relation to the trunk. The hands were proportionally the shortest of any ornithomimosaur and each had three digits with curved claws. The forelimbs were weak while the hindlimbs were proportionally long. The family Ornithomimidae is part of the group Ornithomimosauria. Anserimimus, also from Mongolia, is thought to have been the closest relative of Gallimimus.
As an ornithomimid, Gallimimus would have been a fleet (or cursorial) animal, using its speed to escape predators; its speed has been estimated at 42–56 km/h (29–34 mph). It may have had good vision and intelligence comparable to ratite birds. Gallimimus may have lived in groups, based on the discovery of several specimens preserved in a bone bed. Various theories have been proposed regarding the diet of Gallimimus and other ornithomimids. The highly mobile neck may have helped locate small prey on the ground, but it may also have been an opportunistic omnivore. It has also been suggested that it used small columnar structures in its beak for filter-feeding in water, though these structures may instead have been ridges used for feeding on tough plant material, indicative of a herbivorous diet. Gallimimus is the most commonly found ornithomimosaur in the Nemegt Formation, where it lived alongside its relatives Anserimimus and Deinocheirus. Gallimimus was featured in the movie Jurassic Park, in a scene that was important to the history of special effects, and in shaping the common conception of dinosaurs as bird-like animals.
Discovery[]
Cretaceous-aged dinosaur fossil localities of Mongolia; Gallimimus fossils were collected in area A
Between 1963 and 1965, the Polish Academy of Sciences and the Mongolian Academy of Sciences organised the Polish-Mongolian palaeontological expeditions to the Gobi Desert of Mongolia. Among the dinosaur remains discovered in sand beds of the Nemegt Basin were numerous ornithomimids at different growth stages from the Nemegt, Tsaagan Khushuu, Altan Ula IV and Naran Bulak localities. Three partially complete skeletons, two with skulls, as well as many fragmentary remains, were collected. The largest skeleton (later to become the holotype of Gallimimus bullatus) was discovered by palaeontologist Zofia Kielan-Jaworowska in Tsaagan Khushuu in 1964; it was preserved lying on its back, and the skull was found under its pelvis. One small specimen was also found in Tsaagan Khushuu the same year, and another small specimen was found in the Nemegt locality. A small skeleton without forelimbs was discovered in 1967 by the Mongolian palaeontological expedition in Bugeen Tsav outside the Nemegt Basin. The fossils were housed at the Mongolian, Polish and USSR Academy of Sciences. The Polish-Mongolian expeditions were notable for being led by women, some of whom were among the first women to name new dinosaurs. The fossils discovered in these expeditions shed new light on the interchange of fauna between Asia and North America during the Cretaceous period. Some of the skeletons were exhibited in Warsaw in 1968, mounted in tall, semi-erect postures, which was accepted at the time, though more horizontal postures are favoured today.
In 1972, palaeontologists Halszka Osmólska, Ewa Roniewicz and Rinchen Barsbold named the new genus and species Gallimimus bullatus, using the largest collected skeleton, specimen IGM 100/11 (from Tsaagan Khushuu, formerly referred to as G.I.No.DPS 100/11 and MPD 100/11), as the holotype. The generic name is derived from the Latin gallus, "chicken", and the Greek mimos, "mimic", in reference to the front part of the neck vertebrae which resembled those of the Galliformes. The specific name is derived from the Latin bulla, a gold capsule worn by Roman youth around the neck, in reference to the bulbous capsule on the parasphenoid at the base of the dinosaur's skull. Such a feature had not been described from other reptiles at the time, and was considered unusual. The holotype consists of an almost complete skeleton with a distorted snout, incomplete lower jaw, vertebral series, pelvis, as well as some missing hand and foot bones.
Three skeletons, including the holotype (right) and a juvenile (middle), during a temporary exhibition in CosmoCaixa
The other partially complete skeletons were juveniles; ZPAL MgD-I/1 (from Tsaagan Khushuu) has a crushed skull with a missing tip, damaged vertebrae, fragmented ribs, pectoral girdle and forelimbs, and an incomplete left hind limb, ZPAL MgD-I/94 (from the Nemegt locality) lacks the skull, atlas, tip of the tail, pectoral girdle and forelimbs, while the smallest specimen, IGM 100/10 (from Bugeen Tsav), lacks a pectoral girdle, forelimbs and several vertebrae and ribs. Osmólska and colleagues listed twenty-five known specimens in all, nine of which were only represented by single bones.
At the time it was named, the fossils of Gallimimus represented the most complete and best preserved ornithomimid material yet discovered, and the genus remains one of the best known members of the group. Ornithomimids were previously known mainly from North America, Archaeornithomimus being the only prior known member from Asia (though without a skull). Since the first discoveries, more specimens have been found by further Mongolian-led international expeditions. Three of the Gallimimus skeletons (including the holotype) later became part of a travelling exhibit of Mongolian dinosaur fossils, which toured various countries.
Specimens which were repatriated to Mongolia after having been smuggled to the US, in Central Museum of Mongolian Dinosaurs
Fossil poaching has become a serious problem in Mongolia in the 21st century, and several Gallimimus specimens have been looted. In 2017, Hang-Jae Lee and colleagues reported a fossil trackway discovered in 2009 associated with a clenched Gallimimus foot (specimen MPC-D100F/17). The rest of the skeleton appeared to have been removed previously by poachers, along with several other Gallimimus specimens (as indicated by empty excavation pits, garbage, and scattered broken bones in the quarry). It is unusual to find tracks closely associated with body fossils; some of the tracks are consistent with ornithomimid feet, while others belong to different dinosaurs. In 2014, a slab with two Gallimimus specimens was repatriated to Mongolia along with other dinosaur skeletons, after having been smuggled to the US.
In 1988, the palaeontologist Gregory S. Paul concluded that the skulls of ornithomimids were more similar to each other than previously thought and moved most species into the same genus, Ornithomimus, resulting in the new combination O. bullatus. In 2010, he instead listed it as "Gallimimus (or Struthiomimus) bullatus", but returned to using only the genus name Gallimimus in 2016. The species involved have generally been kept in separate genera by other writers. An ornithomimid vertebra from Japan informally named "Sanchusaurus" was reported in a 1988 magazine, but was assigned to Gallimimus sp. (of uncertain species) by the palaeontologist Dong Zhiming and colleagues in 1990. In 2000, the palaeontologist Philip J. Currie proposed that Anserimimus, which is only known from one skeleton from Mongolia, was a junior synonym of Gallimimus, but this was dismissed by Kobayashi and Barsbold, who pointed out several differences between the two. Barsbold noted some morphological variation among newer Gallimimus specimens, though this has never been published. Barsbold informally referred to a nearly complete skeleton (IGM 100/14) as "Gallimimus mongoliensis", but since it differs from Gallimimus in some details, Yoshitsugu Kobayashi and Barsbold proposed in 2006 that it probably belongs to a different genus.
Description[]
Size compared to a human
Gallimimus is the largest known member of the family Ornithomimidae. The adult holotype (specimen IGM 100/11) was about 6 metres (20 ft) long and 1.9 metres (6.2 ft) tall at the hip; its skull was 330 millimetres (1.08 ft) long and the femur (thigh bone) was 660 millimetres (2.17 ft). It would have weighed about 440 kilograms (970 lb). In comparison, one juvenile specimen (ZPAL MgD-I/94) was about 2.15 metres (7.1 ft) long, 0.79 metres (2.6 ft) tall at the hip, and weighed about 26 kilograms (57 lb). Based on fossils of the related Ornithomimus, it is known that ornithomimosaurs ("ostrich dinosaurs") were feathered, and that the adults bore wing-like structures as evidenced by the presence of quill-knobs on the ulna bone of the lower arm, bumps that indicate where feathers would have attached.
Skull[]
.jpg){kind=link}
Reconstructed skull and neck, NHM
The head of Gallimimus was very small and light compared to the vertebral column. Due to the length of its snout, the skull was long compared to other ornithomimids, and the snout had a gently convex sloping upper profile. The side profile of the snout differed from other ornithomimids in not narrowing towards its front half, and the lower front margin of the premaxilla at the front of the upper jaw rose upwards, instead of being horizontal. Seen from above, the snout was almost spatulate (spoon-shaped), broad and rounded at the tip (or U-shaped), whereas it was acute (or V-shaped) in North American ornithomimids. The orbits (eye sockets) were large and faced sideways, as in other ornithomimids. The temporal region at the side of the skull behind the eyes was deep, and the infratemporal fenestra (the lower opening behind the orbit) was nearly triangular and smaller than that of the related Struthiomimus. It had deep muscle scars at the back part of the skull roof, along the parietal bone. The parasphenoid (a bone of the braincase, at the underside of the skull's base) was thin-walled, hollow and formed a pear-shaped, bulbous structure. The structure had a shallow furrow which opened towards the front. The internal nares (internal openings for the nasal passage) were large and placed far back on the palate, due to the presence of an extensive secondary palate, which was common to ornithomimids.
The delicate lower jaw, consisting of thin bones, was slender and shallow at the front, deepening towards the rear. The front of the mandible was shovel-like, resulting in a gap between the tips of the jaws when shut. The shovel-like shape was similar to that of the common seagull, and the lower beak may have had a shape similar to that of this bird. The retroarticular process at the back of the jaw (where jaw muscles attached that opened the beak) was well developed and consisted mainly of the angular bone. The surangular was the largest bone of the lower jaw, which is usual in theropods. The mandibular fenestra, a sidewards-facing opening in the lower jaw, was elongated and comparatively small. The lower jaw did not have a coronoid process or a supradentary bone, the lack of which is a common feature of beaked theropods (ornithomimosaurs, oviraptorosaurs, therizinosaurs and birds), but unusual among theropods in general. The jaws of Gallimimus were edentulous (toothless), and the front part would have been covered in a keratinous rhamphotheca (horny beak) in life. The beak may have covered a smaller area than in North American relatives, based on the lack of nourishing foramina on the maxilla. The inner side of the beak had small, tightly packed and evenly spaced columnar structures (their exact nature is debated), which were longest at the front and shortening towards the back.
Postcranial skeleton[]
Life restoration showing an adult with feathers, based on those known from the related Ornithomimus
Gallimimus had 64–66 vertebrae in its spine, fewer than other ornithomimids. The centra (or bodies) of the vertebrae were platycoelous, with a flat front surface and a concave hind surface, except for the first six caudal (tail) vertebra–where the hind surface was also flat–and those at the end of the tail–which were amphiplatyan with both surfaces flat. Many of the centra had foramina (openings which have also been called "pleurocoels"), and were therefore probably pneumatic (with their hollow chambers invaded by air sacs). The neck consisted of 10 cervical vertebrae, which were all long and wide, except for the atlas bone (the first vertebra that connects with the back of the skull). The atlas differed from that of other ornithomimids in that the front surface of its intercentrum was slanted downwards towards the back, instead of being concave and facing upwards to support the occipital condyle. The neck appears to have been proportionally longer in relation to the trunk than in other ornithomimids. The neck was divided into two distinct sections: the cervical vertebrae at the front had centra which were nearly triangular in side view and tapered towards the back, as well as low neural arches and short, broad zygapophyses (the processes that articulated between the vertebrae); the cervical vertebrae at the back had spool-like centra which became gradually higher, and long, thin zygapophyses. The pneumatic foramina here were small and oval, and the neural spines projecting outwards from the centra formed long, low and sharp ridges, except for in the hindmost cervical vertebrae.
Pneumatic structures in the caudal vertebrae of Shenzhousaurus (A), and the cervical (B, C, D), dorsal (E), sacral (F, G) and caudal (H) vertebrae of Gallimimus
The back of Gallimimus had 13 dorsal vertebrae, with spool-like centra that were short, but tended to become deeper and longer towards the back. Their transverse processes (processes articulating with the ribs) slightly increased in length towards the back. The two first dorsal centra had deep pneumatic foramina, while the rest only had shallow fossae (depressions), and the neural spines were prominent being somewhat triangular or rectangular in shape. The sacrum (fused vertebrae between the pelvic bones) consisted of five sacral vertebrae which were about equal in length. The centra here were spool-like, flattened sideways and had fossae which appear to have continued as deep foramina in some specimens. The neural spines here were rectangular, broad, and higher than those in the dorsal vertebrae. They were higher or equal in height to the upper margin of the iliac blade and were separate, whereas in other ornithomimids they were fused together. The tail had 36–39 caudal vertebrae with the centra of those at the front being spool-shaped, while those at the back were nearly triangular, and elongated across. The neural spines here were high and flat, but diminished backwards, where they became ridge-like. The only sign of pneumaticity in the tail were deep fossae between the neural spines and the transverse process of the two first caudal vertebrae. All the vertebrae in front of the sacrum bore ribs except for the atlas and the last dorsal vertebra.
The scapula (shoulder blade) was short and curved, thin at the front end, and thick at the back. It was connected relatively weakly with the coracoid, which was large and deep from top to bottom. Overall, the forelimbs did not differ much from those of other ornithomimids, all of which were comparatively weak. The humerus (upper arm bone), which had a near circular cross-section, was long and twisted. The deltopectoral crest on the upper front part of the humerus was comparatively small, and therefore provided little surface for attachment of upper arm muscles. The ulna was slender, long and weakly curved, with a nearly triangular shaft. The olecranon (the projection from the elbow) was prominent in adults, but not well developed in juveniles. The radius (the other bone in the lower arm) was long and slender with a more expanded upper end compared to the lower. The manus (hand) was proportionally short compared to those of other ornithomimosaurs, having the smallest manus to humerus length ratio of any member of the group, but was otherwise similar in structure. It had three fingers, which were similarly developed; the first (the "thumb") was the strongest, the third was the weakest and the second was the longest. The unguals (claw bones) were strong, somewhat curved (that of the first finger was most curved) and compressed sideways with a deep groove on each side. The unguals were similarly developed, though the third was slightly smaller.
Hindlimb bones of ZPAL MgD-I/8, Museum of Evolution of Polish Academy of Sciences
The pubis (pubic bone) was long and slender, ending in a pubic boot which expanded to the front and back, a general feature of ornithomimosaurs. The hind limbs differed little from those of other ornithomimids, and were proportionally longer than in other theropods. The femur was nearly straight, long and slender, with a sideways flattened shaft. The tibia was straight, long, with two well developed condyles (rounded end of a bone) on the upper end and a flattened lower end. The fibula of the lower leg was flat, thin and broad at the upper end narrowing towards the lower end. The lower half of the third metatarsal was broad when viewed end on, partly covering the adjoining two metatarsals to each side, but narrowed abruptly at mid-length, wedging between those bones and disappearing (an arctometatarsalian foot structure). The third toe was proportionally shorter in relation to the limb than in other ornithomimids. As in other ornithomimids, the foot had no hallux (or dewclaw, the first toe of most other theropods). The unguals of the toes were flat on their lower sides; the outer two declined slightly outwards from their digits.
Classification[]
Osmólska and colleagues assigned Gallimimus to the family Ornithomimidae in 1972, with the North American Struthiomimus as the closest relative, while lamenting the fact that comparison between taxa was difficult because other ornithomimids known at the time were either poorly preserved or inadequately described. In 1975, Kielan-Jaworowska stated that though many dinosaurs from Asia were placed in the same families as North American relatives, this category of classification tended to be more inclusive than was used for modern birds. She highlighted that while Gallimimus had a rounded beak (similar to a goose or duck), North American ornithomimids had pointed beaks, a difference that would otherwise lead taxonomists to place modern birds in different families. In 1976, Barsbold placed Ornithomimidae in the new group Ornithomimosauria. In 2003, Kobayashi and Jun-Chang Lü found that Anserimimus was the sister taxon to Gallimimus, both forming a derived (or "advanced") clade with North American genera, which was confirmed by Kobayashi and Barsbold in 2006.
The following cladogram shows the placement of Gallimimus among Ornithomimidae according to Li Xu and colleagues, 2011:
| Ornithomimidae |
| ||||||||||||||||||||||||||||||||||||
Ornithomimosaurs belonged to the clade Maniraptoriformes of coelurosaurian theropods, which also includes modern birds. Early ornithomimosaurs had teeth, which were lost in more derived members of the group. In 2004, Makovicky, Kobayashi, and Currie suggested that most of the early evolutionary history of ornithomimosaurs took place in Asia, where most genera have been discovered, including the most basal (or "primitive") taxa, although they acknowledged that the presence of the basal Pelecanimimus in Europe presents a complication in classification. The group must have dispersed once or twice from Asia to North America across Beringia to account for the Late Cretaceous genera found there. As seen in some other dinosaur groups, ornithomimosaurs were largely restricted to Asia and North America after Europe was separated from Asia by the Turgai Strait.
In 1994, the palaeontologist Thomas R. Holtz grouped ornithomimosaurs and troodontids in a clade, based on shared features such as the presence of a bulbous capsule on the parasphenoid. He named the clade Bullatosauria, based on the specific name of Gallimimus bullatus, which was also in reference to the capsule. In 1998, Holtz instead found that troodontids were basal maniraptorans, meaning that all members of that clade would fall within Bullatosauria, which would therefore become a junior synonym of Maniraptoriformes, and the clade has since fallen out of use.
Paleobiology[]
Skull in Dinosauria Museum
The cervical vertebrae of Gallimimus indicate that it held its neck obliquely, tilting upward at a 35 degree angle. Osmólska and colleagues found that the hands of Gallimimus were non-prehensile, capable of grasping, and that the thumb was not opposable. They also suggested that the arms were weak compared with, for example, those of the ornithomimosaur Deinocheirus . This was in agreement with interpretations of ornithomimid biology made by palaeontologist Dale Russell from early 1972, including that they would have been running animals, albeit less agile than large modern land birds, and would have used their speed to escape predators. Russell also suggested that they had a good sense of vision and intelligence comparable to that of modern ratite birds. Since its predators may have had colour vision, he suggested that this would have influenced its colouration, perhaps resulting in camouflage. In 1982, palaeontologist Richard A. Thulborn estimated that Gallimimus might have run at speeds of 42–56 km/h (26–35 mph). He found that ornithimids would not have been as fast as ostriches, which can reach 70–80 km/h (44–50 mph), partly due to their arms and tails adding weight.
Skull cast of the juvenile specimen ZPAL MgD-I/1, National Museum of Natural History
In 1988, Paul suggested that ornithomimid eyeballs were flattened and had minimal mobility within the sockets, requiring head movement to see objects. Since their eyes were more sideways-oriented than in other bird-like theropods, their binocular vision would have been more limited, which is an adaptation in some animals that improves their ability to see predators behind them. Paul considered the relatively short, weight-reducing tails and missing haluxes of ornithomimids to be adaptations for speed. He suggested that they might have defended themselves by pecking and kicking, but would have relied primarily on their speed to escape. In 2015, Akinobu Watanabe and colleagues found that along with Deinocheirus and Archaeornithomimus , Gallimimus had the most pneumatized skeleton among ornithomimosaurs. Pneumatization is thought to be advantageous for flight in modern birds, but its function in non-avian dinosaurs is not known with certainty. It has been proposed that pneumatization was used to reduce the mass of large bones, was related to high metabolism, balance during locomotion, or was used for thermoregulation.
In 2017, Lee and colleagues suggested several possible taphonomic circumstances, changes during decomposition, and fossilization to explain how the Gallimimus foot discovered in 2009 became associated with a track. The track is preserved in sandstone, while the foot is preserved in sandstone, extending 20 centimeters below the trackbed layer. It is possible that the fossil represents an animal that died on its way, but the depth of the foot in the mud may be too shallow for it to have become bogged down. It may also have been killed by a flood, after which it was buried in a pond. However, the layers of mud and sand do not indicate flooding but probably a dry environment, and the disorganized sediments around the fossil indicate that the animal was alive when it arrived in the area. The authors therefore suggested that the footprints had been made over an extended period of time and drying period, and that probably none of them were produced by the individual who owned the foot. The animal may have walked across the floor of a pond, traversing the sediment layer with the footprints while soaked from rain or contained water. The animal may have died in this position from thirst, hunger, or another reason, and mud was then deposited on the sand, covering and preserving the footprints and carcass. The foot may have become squeezed and disarticulated as it decomposed, causing the tendons to flex, and was then stepped on by heavy dinosaurs. The area may have been a single bone bed, based on the possible number of specimens captured, representing a mass mortality of Gallimimus , perhaps due to drought or famine. The fact that the animals appear to have died at the same time—the empty excavation pits were stratigraphically identical—may indicate that Gallimimus was gregarious, which has also been suggested for other ornithomimids.
Ontogeny[]
A 1987 study by biologists R. Pawlicki and P. Bolechała showed age-related differences in the calcium and phosphorus content, important components in bone formation, of Gallimimus specimens . They found that the ratio was highest in young and middle-aged animals, decreasing with age. In 1991, they reported that bones of old individuals contained the highest amounts of lead and iron, while those of younger animals were lower. A study of the bone histology of various dinosaurs in 2000, by biologists John M. Rensberger and Mahito Watabe, revealed that the canaliculi—channels connecting bone cells and collagen, fiber bundles—of Gallimimus and other ornithomimids were more similar to those of birds than mammals, unlike ornithischian dinosaurs, which were more mammal-like. These differences may have been related to the process and rate at which the bone was formed. In 2012, paleontologist Darla K. Zelenitsky and colleagues concluded that since adult ornithomimosaurs had wing-like structures on their arms, while juveniles did not, as evidenced by Ornithomimus specimens , these structures were originally secondary sexual characteristics, which could have been used for reproductive behavior such as courtship, display, and parenting.
Feeding strategies[]
.jpg){kind=link}
Reconstructed skull and neck in front view, NHM
Osmólska and her colleagues noted that the front part of the neck of Gallimimus would have been highly mobile and the back part was stiffer, the neural arches in the vertebrae in that region were similar to those of roosters and other galliformes, indicating similar feeding habits. They found the beak of Gallimimus similar to that of a duck or goose and it would have fed on small, live prey which it swallowed whole. The mobility of the neck would have been useful in locating prey on the ground, as the eyes were positioned on the sides of the skull. They assumed that all ornithomimids had similar feeding habits and noted that Russel had compared ornithomimid beaks to those of insectivorous birds. Osmólska and her colleagues suggested that Gallimimus was capable of cranial kinesis, due to the apparently loose connection between some of the bones at the back of the skull, a feature that allows individual bones of the skull to move relative to each other. They also proposed that it did not use its forelimbs to carry food to its mouth, but rather to rake or dig through the ground to access food. The hands of Gallimimus may have been weaker than, for example, those of Struthiomimus , which may instead have used its hands for hooking and grasping, according to a 1985 paper by paleontologists Elizabeth L. Nicholls and Anthony P. Russell.
In 1988, Paul disagreed that ornithomimids were omnivores that ate small animals, eggs and plants, as had been previously suggested. He noted that ostriches and emus are primarily grazers and browsers and that ornithomimid skulls were more similar to those of the extinct moas, which were strong enough to chew twigs, as evidenced by their gut contents. He further suggested that ornithomimids were well adapted to feeding on tough plants and would have used their hands to bring branches within reach of their jaws. Palaeontologist Jørn Hurum suggested in 2001 that due to its similar jaw structure, Gallimimus may have had an opportunistic, omnivorous diet, like gulls. He also noted that the tight intramandibular junction would prevent any movement between the front and back parts of the lower jaw.
.jpg){kind=link}
The beak of Gallimimus contained structures which have been compared to the lamellae of, for example, the Northern shoveller, or the ridges in the beaks of turtles and hadrosaurids.
In 2001, paleontologists Mark A. Norell, Makovicky, and Currie published a Gallimimus skull , IGM 100/1133 , and an Ornithomimus skull that preserved soft tissue structures in the beak. The inner side of the Gallimimus beak had columnar structures that the authors found similar to the lamellae on the beaks of anseriform birds , which use them to manipulate food, filter sediment, separate food from other materials, and to shear plants during grazing. They found the shoveler, which fed on plants, mollusks, ostracods, and foraminifera, to be the modern anseriform with structures most similar in anatomy to those of Gallimimus . The authors noted that ornithomimids probably did not use their beaks to hunt large animals and were abundant in mesic environments, while being rarer in more arid environments, suggesting that they may have relied on aquatic food sources. If this interpretation is correct, Gallimimus would have been one of the largest known terrestrial filter feeders.
In 2005, paleontologist Paul Barrett noted that the lamella-like structures of Gallimimus did not appear to be flexible bristles like those on filter-feeding birds, as there is no indication that these structures overlapped or collapsed, but were instead more similar to the thin, regularly spaced vertical ridges on the beaks of turtles and hadrosaurid dinosaurs. In these animals, such ridges are thought to be associated with herbivorous diets, used to grind up tough vegetation. Barrett suggested that the ridges on the beak of Gallimimus represented a natural casting of the inner surface of the beak, indicating that the animal was an herbivore that fed on high-fiber material. The discovery of many gastroliths, or gizzard stones, in some ornithomimids indicates the presence of a gastric mill and therefore points towards a herbivorous diet, as they are used to grind food from animals lacking the necessary masticatory apparatus. Barrett also calculated that the 440-kilogram Gallimimus would have needed between 0.07 and 3.34 kilograms of food per day, depending on whether it had an endothermic or ectothermic metabolism, an intake that would not have been feasible if it was a filter feeder. He also found that ornithomimids were abundant not only in formations representing mesic environments, but also in arid environments where there would not be enough water to support a filter-feeding diet. In 2007, paleontologist Espen M. Knutsen wrote that the beak shape of ornithomimids, compared to those of modern birds, was consistent with an omnivore or a high-fiber vegetable herbivore.
Paleoenvironments[]
Two Gallimimus (right foreground) with contemporary dinosaurs of the Nemegt Formation
Gallimimus is known from the Nemegt Formation in the Gobi Desert of southern Mongolia. This geological formation has never been radiometrically dated, but the fauna present in the fossil record indicates that it was probably deposited during the early Maastrichtian stage, at the end of the Late Cretaceous about 70 million years ago. Sediments from the type locality of Gallimimus , Tsaagan Khushuu consist of silts, siltstones, mudstones, sands, as well as less frequent thin layers of sandstones. The rock facies of the Nemegt Formation suggest the presence of river channels, marshes, shallow lakes and floodplains in a setting similar to the Okavango Delta of present-day Botswana. The large river channels and soil deposits are evidence of a significantly wetter climate than the older Barun Goyot and Djadochta Formations. Although caliche deposits indicate that periodic droughts occurred, fossil bones from the Nemegt Basin, including Gallimimus , are more radioactive than fossils from surrounding areas, possibly because uranium accumulates in the bones, transported there by seeping groundwater.
The Nemegt Rivers, where Gallimimus lived , were home to a wide variety of organisms. Occasional mollusc fossils have been discovered in this region, as well as a variety of other aquatic animals such as fish, turtles, and crocodylomorphs including Shamosuchus . Mammal fossils are rare in the Nemegt Formation, but many birds have been found, including Enantiornithes Gurilynia , Hesperornithes Judinornis , and Teviornis , a possible anseriform. Herbivorous dinosaurs discovered in the Nemegt Formation include ankylosaurids such as Tarchia , the pachycephalosaur Prenocephale , large hadrosaurids such as Saurolophus and Barsboldia , and sauropods such as Nemegtosaurus and Opisthocoelicaudia . Predatory theropods that lived alongside Gallimimus include tyrannosauroids such as Tarbosaurus , Alioramus , and Bagaraatan , and troodontids such as Borogovia , Tochisaurus , and Zanabazar . Herbivorous or omnivorous theropods include thericinosaurians, such as Therizinosaurus , as well as oviraptorosaurians, such as Elmisaurus , Nemegtomaia , and Rinchenia . Other ornithomimosaurs are also found, including Anserimimus and Deinocheirus , but Gallimimus is the most common member of the group in the Nemegt Formation.
Anatomy[]
It is likely that Gallimimus was a very intelligent creature, based on mass and the proportion to the brain, meaning that they were probably quite smart among most dinosaurs. It shared many features with its relatives. such as Struthiomimus and Ornithomimus. It is guessed that Gallimimus was an omnivore, similiar to the Oviraptor. Its main diet consisted of small lizards and bugs, some eggs, and some plants. Gallimimus ran on two slender legs. It's predicted to have been ostrich-like, and most likely had feathers, given that feathers were preserved in it's relatives and more massive feathered dinosaurs did exist. It had a long, flat, toothless beak, with the lower jaw being shaped like a shovel, a tool which would have probably been helpful in crunching hard materials like nuts or roots. It weighed about 970 lbs and was about 8 meters (26 feet) in length, making it one of the largest of ornithomimids. It had three claws on each arm, with three on each foot. The tail, like many other dinosaurs, was meant for balance, especially while they were running. Like other ornithomimids, it was a very fast runner, possibly capable of running up to 50 mph, which is about the same as an ostirich's top speed and over twice as fast as Olympic sprinters! Gallimimus also had large eyes, which possibly suggests that they were nocturnal dinosaurs like the Troodon.
JPInstitute.com Description[]
Gallimimus was a speedy predator, the largest of its type. They were called chicken mimics because they probably moved like modern flightless birds. Unlike other meat-eaters, Gallimimus had no teeth. In fact, it had a very small head. This was probably one of the fastest dinosaurs, with speed like a modern cheetah, it could probably run up to 60 mph.
With its small, toothless head, it is believed that Gallimimus probably had a diet of insects, small animals, eggs and maybe even some plants. They hand very long fingers and long arms, which they could use for digging or grabbing eggs. They had a much longer neck that any other therapod dinosaur. In Jurassic Park they were shown as large flock, but we don't know if that was real or movie behavior.
Dinosaur Field Guide Description[]
Gallimimus ("chicken mimic") is one of the largest of the ornithomimosaurs (or "bird mimics"). Ornithomimosaurs are often called "ostrich dinosaurs" because they are shaped very similar to modern flightless birds. Ostrich dinosaurs were compact, with long arms and legs. The arms ended in long hands with hook-like fingers all curling in the same direction. Their feet were long, narrow, and compact, and had a special shock-absorbing shape that let them run very fast. In fact, ostrich dinosaurs were probably the fastest dinosaurs of the Cretaceous Period. This would have been useful, since both raptors and tyrant dinosaurs hunted in the places where Gallimimus and its relatives lived! Although Pelecanimimus and other early ostrich dinosaurs had teeth in their jaws, Gallimimus and its relatives were totally toothless. Their beaked heads had large eyes and were at the end of long, slender necks. Some paleontologists think that ostrich dinosaurs ate only meat, although without good grasping hand or strong jaws they could kill only smaller animals, Others think that they were plant-eaters. Many suspect that like the modern ostrich, they ate small animals and plants.
Fun Facts[]
Gallimimus may not be the largest of all the ostrich dinosaurs. The arms and hands of Deinocheirus from Mongolia seem to be the size of T. rex.
Trivia[]
In Jurassic Park, Gallimimus is shown living in flocks. Paleontologists have not found skeletons of different Gallimimus together, but there are reports of such a discovery for an earlier Mongolian ostrich dinosaur.
Gallery[]
Appearance in other media[]
Jurassic Park[]
- Gallimimus was shown in nearly all of the Jurassic Park films, with the exception of Jurassic Park III. In the 1st film, a herd of them was briefly seen as a stampeding herd that ran at three of the protagonists, and one was then attacked and eaten by Rexy the Tyrannosaurus rex. In the 2nd film, they were known to have resided in the southeast of Isla Sorna coexisting with other herbivores Mamenchisaurus, Parasaurolophus, and Pachycephalosaurus. Gallimimus also made up a good portion of the fauna of that region. The two adults were captured by the InGen Hunters for Peter Ludlow's Jurassic Park San Diego, but was freed the following night by Nick Van Owen and the Gatherers along with the rest of the dinosaurs held captive by the hunters. In the 4th film, they retained many characteristics of the previous clones albeit being a foot taller and having teeth which is inaccurate to the real animal and being different colors, orange with a creamy underbelly and brown stripes on the backs. The theropods lived in the self-titled Gallimimus Valley. Some of the juveniles also lived in the Gentle Giants Petting Zoo. In the 5th film, it is revealed that there are surviving Gallimimus populations on Isla Nublar, as they will now face an impending danger, alongside many other creatures, in the form of an erupting volcano. They were seen running alongside many other species away from Mount Sibo.
- Gallimimus appears in Jurassic World: Evolution as revealed by its' species profile. Its' design is based on the Jurassic World and Jurassic World: Fallen Kingdom variants.
- Gallimimus is a common in Jurassic World: Alive Its' design is based on the Jurassic World and Jurassic World: Fallen Kingdom variants.
 |
Read more Gallimimus on Jurassic Park Wiki |
The Land Before Time[]
Links[]
References[]
http://en.wikipedia.org/wiki/Gallimimus
http://animals.howstuffworks.com/dinosaurs/gallimimus.htm
http://www.prehistoric-wildlife.com/species/g/gallimimus.html
https://paleontologyworld.com/dinosaurs-%E2%80%93-species-encycolpedia/gallimimus