What is an Ornithomimus?
Ornithomimus was one of the fastest dinosaurs that could reach a speed of 80 km/h. It looked similar to the ostriches we know today. It had three fingers and toes, long thin arms, a long neck and a small skull.
Added to this was a long snout that ended in a beak devoid of teeth. The most complete material of this specimen was found in Alberta, Canada, in what is known as the Horseshoe Canyon Formation.
What made Ornithomimus stand out from other ornithomimids was a shorter torso, long, thin forearms, and very thin, straight claws on the hands and feet.
As is usual in specimens of this family, it had feathers, something that has been proven in the discovery of fossils of juvenile and adult individuals. Its structure was made of feathers that in adult specimens were longer on the arms.
All these characteristics that gave it the appearance of a bird motivated its name, which means bird imitator. The diet of Ornithomimus was omnivorous and is thought to have included crustaceans, fruits, leaves, eggs, insects, lizards and small mammals.
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Ornithomimus discovery
In 1890, Othniel Charles Marsh named what is known as the type species, which is Ornithomimus velox. It was based on remains found by George Lyman Cannon in Colorado.
At the same time Marsh appointed Ornithomimus tenuis and Ornithomimus grandis by studying fossils found by John Bella Hatcher in Montana.
Marsh initially classified it as an ornithopod. But this was reconsidered when Hatcher discovered new remains that Marsh called Ornithomimus sedana in the year 1892.
Then he was also named Ornithomimus minutus which was later recognized as Alvarezsauridae.
There are many cases assigned to this species, such as that of Ornithomimus alutus which was named in 1902 by Lawrence Lambe. Added to this is the appointment of Ornithomimus affinis in 1920. Loris Russell also renamed the Struthiomimus brevetertius parks and to Struthiomimus samuelli parks as Ornithomimus samueli.
Finally Charles Mortram Sternber in 1933 named a skeleton found in the Horseshoe Canyon Formation as Ornithomimus edmontonicus.
There was great confusion surrounding the species, as each newly discovered ornithomimid was assigned to Ornithomimus. Added to this is the fact that everything related to ornithomimus was referred to as Struthiomimus.
With the intention of resolving this confusion, Dale Russell carried out a morphometric study that established the differences in proportions that allowed a clearer distinction. As a consequence he determined that Struthiomimus and Ornithomimus were valid genera.
Thus he recognized the Ornithomimus velox and Ornithomimus edmontonicus. He also assigned the Archaeornithomimus to the Ornithomimus asiaticus and the Ornithomimus affinis became the Archaeornithomimus asiaticus.
The difficulties in its classification lie in its complex taxonomy, which remains a source of confusion today. It was considered that there were 18 different species of Ornithomimus.
Many of these were found to belong to the type species and others were finally shown to be unrelated. Currently it is considered valid to Ornithomimus velox, Ornithomimus edmonticus and Ornithomimus sedens.
The first remains of Ornithomimus were discovered in 1889 by George Lyman Cannon in Denver. Othniel Charles Marsh named her as O. velox in 1890 and made him the typical specimen.
Later in 1891, after the discovery of partial remains in the Lancen Formation in Wyoming, the O. sedens.
Charles Sternenberg appointed in 1930 O. edmontonicus from a practically complete skeleton found in Alberta, Canada.
What does Ornithomimus mean?
The name comes from Greek ornis which is a bird and pampering what does it mean mimic or imitator. This refers to its appearance quite similar to that of a bird. That’s why its name means bird imitator either mimic bird. The epithet velox which in Latin is fastwas chosen because it was possibly very fast.
The Ornithomimosauria family
Ornithomimus is part of the Ornithomimosauria family. This group of lizards that imitate birds They were omnivorous theropods with a slight resemblance to rats, but with an overall appearance closer to birds.
They were bipeds and lived in Laurasia, a territory that combined North America, Asia and Europe, during the Cretaceous. Their skulls were small and they had large eyes. Her neck was long and thin.. Specimens such as Pelecanimimus and Harpymimus had teeth. But most of them had only a beak without teeth.
Its front limbs were thin, long and ended in powerful claws. Its hind legs were strong, long and had a long foot, with short, strong toes.
They were very fast dinosaurs. They had thin plumage, made up mostly of down. The adults possessed longer feathers on the front limbs, making them more similar to today’s birds.
As with ostriches, the long feathers may have been used for display and to gain a sexual partner. They also helped incubate their eggs.
The food possibly consisted of primitive species in combination with fruits and various vegetables. In some species, gastroliths have been discovered that they used to process the food they ingested.
The discovery of several specimens together would indicate that they lived in groups, possibly for a time.
The fact that they ate animals is a source of controversy among some specialists. But even if they were theropods, they were not predators. This is due to their weak hands and eyes set into the skull laterally, traits that would not allow them to be the best hunters.
The lamellae found in the beak of Gallimimus are considered a filter device with which small creatures were strained out of the water. It would also have served to trap insects effectively.
Characteristics of Ornithomimus
This species has been studied thanks to its good fossil record, which has allowed us to know the following particularities.
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Classification
Ornithomimus was classified in 1890 as part of the Ornithomimosauria by Othniel Charles Marsh. Currently it is indicated that it has a derived position in ornithomimids, especially from the Ornithomimus edmontonicus.
Attributes and description
Ornithomimus had a large brain for its body, and that is why it is thought to be one of the most intelligent dinosaurs. However, some specialists think that the enlarged parts of the brain were dedicated to kinesthetic coordination.
They had large eye sockets, which could be a sign that they had good eyesight. The large size of the eyes could also indicate the possibility that it was nocturnal. They also had hollow bones that helped them keep their weight low and move with agility.
Since only parts of skeletons have been found, paleontologists are not sure of their actual size. They estimate that it was between 3.5 and 6 meters long, between 1.8 and 2.4 meters high and that it weighed a minimum of 170 kg and a maximum of 350 kg..
Feeding
Being a theropod dinosaur there was a good chance that it was carnivorous. However, many of its characteristics were consistent with those of a herbivore. Finally, it was concluded that it fed on animal and plant sources, in an omnivorous diet.
Therefore its diet would include insects, terrestrial crustaceans such as mealybugs, fruits, eggs, berries, plants, seeds and leaves. He would also feed on small reptiles and mammals.
Motion
This dinosaur walked on its two hind legs so it was bipedal. Paleontologists think that he was fast and agile, because his legs were suitable for him to move quickly. His tibia was 20% longer than his femur.
It had a long tail that acted as a stabilizer, allowing it to spin at high speed. It is estimated that it could run at 70 km/h, making it the fastest dinosaur in its environment.
This speed was most likely its defense mechanism, in the absence of other resources, such as large claws, teeth or great size. Stampeding away in packs would be effective enough to get away from predators.
Where he lived
Ornithomimus lived 70 million years ago in the last phase of the Cretaceous, where he would have wandered through the swamps and forests of what is now North America. Therefore he lived in what is now Arizona, Colorado and Montana in the United States and in Alberta in Canada.
It lived with Albertosaurus, Euoplecephalus, Kritosaurus, Nanotyrannus and Parasaurolophus. The scleral rings of Ornithomimus revealed to specialists that its lifestyle was cathemeral. That is, it was active for short periods, both during the day and at night.
Reproduction
Although it is presumably oviparous, paleontologists have not discovered eggs or eggshell fragments of Ornithomimus. In fact, they have not found those of any ornithomimid.
The reason for this could be that they nested in environments where their eggs were unlikely to become trapped by river sediments, leading to their fossilization.
A recent study proposed that most dinosaurs laid soft-shelled eggs, just as turtles and lizards are known to do. Because of this, it would be unlikely that studyable remains would be preserved today.
What paleontologists do have are fossils of baby ornithomimids. A partial skeleton of a one-year-old Ornithomimus reveals that it was about 1.5 meters in length. Juvenile specimens had filamentous feathers, but lacked wings like adults.
These were developed when the animal reached sexual maturity, since it needed them for mating courtship, display and also to keep the eggs and babies warm.
Behavior
Ornithomimus traveled in small herds, according to the various sites with footprints and beds of ornithomimid bones in Asia. They gathered in groups of 14 individuals, or even a little more.
These herds were made up of young individuals up to 2 years old and older individuals between 3 and 7 years old. They were not accompanied by adults, which suggests that the young lived apart from their elders, until reaching the age of reproduction.
In North America ornithomimid specimens were generally found alone. However, at a fossil site in the Horseshoe Canyon Formation in Alberta, three developed individuals are preserved that were buried together. This suggests that North American ornithomimids also lived in herds.
By studying the shape and size of the Ornithomimus brain, it was concluded that its sense of smell was not very developed, so it is possible that it depended more on…