Ornithomimus

Named in‭ ‬1890‭ ‬from a partial hand and foot,‭ *‬Ornithomimus* became the first known ornithomimid,‭ ‬which is why it is considered the type genus of the Ornithomimidae.‭ ‬The ornithomimds‭ (‬also sometimes called‭ '‬ostrich dinosaurs‭’) ‬were small dinosaurs that usually ranged between three and four meters long,‭ ‬although some were slightly larger.‭ ‬During the late Cretaceous ornithomimds seem to have been particularly widespread across North America and Asia where they relied upon speed for survival in habitats that were dominated by tyrannosaurs,‭ ‬and shared with horned and armoured dinosaurs like ceratopsians and ankylosaurs.

       Amongst the dinosaurs *Ornithomimus* has one of the most complicated taxonomic histories that continue to cause much confusion amongst researchers.‭ ‬In a nut shell,‭ ‬because it was one of the first ornithomimds discovered,‭ *‬Ornithomimus* along with *Struthiomimus* were effectively used as wastebasket taxons where any remains remotely resembling the earlier material were almost automatically attributed to one of these genera as a new species.‭ ‬This also happened for the first two dinosaur genera ever named,‭ *‬Megalosaurus* and *Iguanodon*,‭ ‬although perhaps a better analogy would come from the pterosaurs *Pterodactylus* and *Rhamphorhynchus*.‭ ‬Both of these genera once had an incredible number of species attributed to them,‭ ‬just for most of them to be found to be the same as the type species or actually different genera completely.
       The classification of *Ornithomimus* didn’t really get under way properly until‭ ‬1972‭ ‬when palaeontologist Dale Russel undertook a review of the ornithomimids.‭ ‬The result of Russel’s study was that *Ornithomimus* along with *Struthiomimus* were each themselves valid genera and that *Ornithomimus* had two distinct species,‭ *‬O.‭ ‬velox* and *O.‭ ‬edmontonicus*,‭ ‬even though the line between these two species was occasionally blurry.‭ ‬Russel additionally created two new ornithomimid genera of *Archaeornithomimus* and *Dromiceiomimus* on the basis that some *Ornithomimus* remains could not be placed‭ ‬with‭ ‬the genus.
       Other palaeontologists have continued to study *Ornithomimus* and other closely related genera,‭ ‬but results and conclusions have been mixed between different researchers.‭ ‬Further species have been named only to be contested by others who claim there is not enough difference.‭ ‬Additionally the earlier creation of *Dromiceiomimus* is now seen as invalid and this genus is now usually attributed as a synonym to *Ornithomimus* where the fossil material originally belonged.‭ ‬It is hard to say for certain what the future holds for *Ornithomimus*,‭ ‬although its place a valid genus is not in dispute.‭ ‬Further remains and study however may yet bring a change in the number of valid species.

       It is actually a lot easier to talk about *Ornithomimus* as a dinosaur rather than its taxonomic history.‭ ‬Like with all other ornithomimids,‭ *‬Ornithomimus* is noted for having long legs,‭ ‬the lower portions of which were considerably longer than the femur.‭ ‬This is a sure sign that *Ornithomimus* was a dinosaur that was built for speed and with the exception of other ornithomimids,‭ ‬was probably the fastest dinosaur in its ecosystem.‭ ‬This speed would have probably been enough to keep it out of the way of big predators like *Tyrannosaurus* and *Albertosaurus*,‭ ‬although it would be interesting to see how *Ornithomimus* faired against smaller and faster predatory dinosaurs,‭ ‬including juveniles of the big tyrannosaurs.‭ ‬To help reduce weight the bones of *Ornithomimus*,‭ ‬like other ornithomimids,‭ ‬were hollow.‭ ‬Another adaptation to fast running is the tail which in life would have been carried off the ground and supported with tendons so that it could be used as a stiff balancing aid.
       The obvious tactic for a predator to employ against a fast animal like *Ornithomimus* would be ambush,‭ ‬dashing out from cover and closing the gap between themselves and their target before the prey could turn and use their speed to escape.‭ ‬This was not all that easy to do either however,‭ ‬as *Ornithomimus* had a head that was carried high from the body by a long neck.‭ ‬This meant that *Ornithomimus* could see over cover and see other dinosaurs approaching from a long way off which would make sneaking up on one very difficult.‭ ‬The large orbital fenestrae of the skull also suggest proportionately larger eyes to fit within them.‭ ‬This indicates that *Ornithomimus* would have had keen vision,‭ ‬possibly even for seeing at night.‭ ‬Analysis of sceleral rings has indicated a cathemeral lifestyle,‭ ‬which means that *Ornithomimus* would have been active for short periods during both the day and night time hours.
       Another feature of the skull is the enlarged brain cavity that also suggests that *Ornithomimus* had a large and well developed brain for its size.‭ ‬Although it is tempting to say that this may have made *Ornithomimus* an intelligent dinosaur,‭ ‬it is not so much the case of how big the brain is as a whole,‭ ‬but the development of certain parts.‭ ‬The development of the brain in *Ornithomimus* is usually taken as being towards proprioception,‭ ‬or in‭ ‬simple terms better control over the body and its movements.‭ ‬This is a very logical conclusion when you think that a bipedal dinosaur that was capable of breaking the speed limit on some of our roads would need excellent coordination when running over rough terrain while being chased by a predator.
       Rather than having more typical jaws with teeth,‭ *‬Ornithomimus* actually had a mouth that was more like a beak which could have been used for a variety of feeding styles.‭ ‬As a theropod *Ornithomimus* is thought to have descended from carnivorous ancestors,‭ ‬but it is still uncertain if it ate meat as well.‭ ‬The beak-like mouth could have been used to selectively browse certain parts of plants,‭ ‬or alternatively *Ornithomimus* could have used it to pick up insects.‭ *‬Ornithomimus* may have also preyed upon small animals like lizards and primitive mammals that it may have caught by using its long neck to reach into the undergrowth.‭ ‬It is also possible that all of the above might be correct and that *Ornithomimus* was an omnivore which browsed the landscape eating whatever it could find and thereby not competing with other more specialised groups of dinosaurs.‭ ‬Regardless of what it ate,‭ ‬the lack of teeth would at least suggest that *Ornithomimus* swallowed food whole.
       The arms of *Ornithomimus* are also quite long with long fingers to match.‭ ‬It has been suggested that these long arms were used to reach out and grab branches in the same way that a sloth feeds,‭ ‬although it’s uncertain how much benefit if any *Ornithomimus* would have gained from this because it already had a long relatively long neck for this purpose already.‭ ‬It’s possible that the long arms and hands may have played a bigger part in prey capture,‭ ‬since the mouth lacked teeth to grip hold of prey.‭ ‬If *Ornithomimus* raided nests for eggs as has been suggested in the past,‭ ‬then it may have held onto eggs within its hands while the beak-like mouth broke the shell and dipped into the yolk within.
       One area where *Ornithomimus* differs from other ornithomimids is that it had a shorter actual body length.‭ ‬This may indicate an adaptation for greater agility in this genus as a shorter bodied animal would be able to make tighter turns than a longer bodied animal.‭ ‬Another area of study now concerning *Ornithomimus* is if it actually had hair like feathers over its body.‭ ‬To date no evidence has been found to suggest this for *Ornithomimus* directly,‭ ‬but other ornithomimids,‭ ‬specifically from Asia where conditions are better for the preservation of hair and feathers have led to the suggestion that at least juveniles may have had a downy feather covering.‭ ‬It remains to be seen however if this existed in adults or even other genera.