Dilophosaurus

*Dilophosaurus* is a very distinctive dinosaur that is instantly recognisable by the two crests that are on top of its neck.‭ ‬It must be remembered however that *Dilophosaurus* never had a neck frill or spat venom, as was depicted in the 1993 film *Jurassic Park*.‭ ‬Those were the creations of artistic licence,‭ ‬not paleontological fact.‭

      The crests themselves are most likely there for display,‭ ‬and could have been brightly coloured,‭ ‬particularly in the males.‭ ‬The crests are usually found disarticulated from the skull,‭ ‬but careful reconstruction has shown that they most likely sat on top of the skull.‭ ‬This arrangement is also considered more accurate than some earlier artistic reconstructions that have the crests running from the back of the skull and onto the neck.‭ ‬Such a reconstruction would have restricted the movement of the neck vertebra,‭ ‬a flawed configuration for a predator,‭ ‬hence the acceptance of the crests on top of the skull.

      The skull also features a large notch in the upper jaw between the teeth of the pre-maxilla and maxilla.‭ ‬This notch is actually an inherent weakness in the skull and suggests that *Dilophosaurus* probably did not have a high bite force as other similarly sized dinosaurs that lacked the notch.‭ ‬One theory is that the notch would have enabled *Dilophosaurus* to dig out small prey items out of things like rock crevices,‭ ‬although bearing in mind that it was six meters long,‭ ‬it would not really be an efficient method of feeding for such a large dinosaur.‭ ‬Another theory is that *Dilophosaurus* lived the life of a scavenger.‭ ‬In this scenario *Dilophosaurus* would only need a bite force large enough to tear meat from a carcass,‭ ‬and could have used its size to intimidate and drive off smaller carnivores from their kill.‭

      The notch may yet prove to be a bit of a red herring in describing its feeding behaviour.‭ ‬There were other dinosaurs present that were well within the predatory scope of *Dilophosaurus* and it may have also employed the use of its claws in making kills.‭ ‬The notch may have even been of use in picking flesh off the bones off kills as a weaker bite force would mean that *Dilophosaurus* may have had difficulty in crunching bones.‭ ‬All that can be said is that carnivores in general will kill an animal for food when able,‭ ‬but will also scavenge carrion when the opportunity presents itself.

      A smaller version of this notch is also present in the earlier dinosaur *Coelophysis*,‭ ‬and it is part of the reason why some palaeontologists think that *Dilophosaurus* and *Coelophysis* have a common lineage,‭ ‬with *Dilophosaurus* maybe being a direct descendent of *Coelophysis*.‭ ‬Unfortunately there are so many possible ways that *Coelophysis* fits in with other dinosaurs that it‭’‬s hard to pick one out as being more likely.

      One *Dilophosaurus* specimen shows an underdeveloped left arm that has a reduced humerus,‭ ‬while the right is quite robust.‭ ‬This discrepancy may have been caused by harsh living conditions and could be an example of fluctuating asymmetry.‭ ‬The majority of animal organisms have completely symmetrical body morphology and when one differs from the rest in this way,‭ ‬the answer is either genetic or the result of an outside factor.

      When first discovered in‭ ‬1942,‭ ‬the *Dilophosaurus* specimen was lacking the head crests and was named *Megalosaurus wetherilli*.‭ ‬It was not until another and more complete specimen that featured the crests was recovered over a decade later that the distinction could be made.‭ ‬The fact that three *Dilophosaurus* individuals were found together has lent support to the theory that some dinosaurs hunted in packs. *Dilophsaurus* is now the type genus of its own special group of theropod dinosaurs called the Dilophosauridae.

      In 1993 a second species of *Dilophsaurus* called *D. sinensis* was named. Later analysis of this species however has now determined that it is not a species of *Dilophosaurus* but a separate genus, and is now known as *Sinosaurus*.