Dilophosaurus

Dilophosaurus was a meat-eating dinosaur that lived in what's now North America.

It gets its name - meaning 'two-crested lizard' - from the distinctive double crests on top of its head.

In life, they would probably be covered with hard keratin, the same material that makes up human hair and fingernails. The crests may have looked larger or a different shape to what we can see from the fossil skull.

Nobody is certain what the crests were for. The most likely theories are that the dinosaur used them to identify other Dilophosaurus or to attract a mate. The crests probably weren't strong enough to have any use in combat.

A Navajo man named Jesse Williams found the first partial Dilophosaurus skeletons on a reservation in Arizona, USA.

The fossils were first studied by Samuel Welles, a scientist from California. To start with, he thought they belonged to a new species of Megalosaurus.

But a decade later, Welles found a fossil showing the distinctive head crests. He realised the dinosaur was distinct enough to need a new name - Dilophosaurus. It was the first meat-eating dinosaur ever found with skull crests. Others identified since include Cryolophosaurus, Monolophosaurus, and Guanlong.

More Dilophosaurus specimens were unearthed in 2001, showing previously unseen parts of the skeleton.

In the 1990 novel Jurassic Park, Dilophosaurus was given the ability to spit venom. But there's no fossil evidence of this.

Author Michael Crichton wanted to show that a dinosaur recreated from ancient DNA could be unpredictably dangerous, so he created the venom idea to illustrate this. Some living animals, such as spitting cobras and spitting spiders, do have this ability.

In the 1993 movie adaptation, director Steven Spielberg and his design team also gave Dilophosaurus an expanding neck frill. This was another, more visual way to show that an extinct animal could have surprising traits.

While the venom and neck frill were artistic creations for Jurassic Park, it's always possible that any dinosaur had unusual attributes that their fossils don't show.

Dilophosaurus lived around 184 million years ago during the Early Jurassic Period.

At this time, the North American environment was a desert with many rivers. As the seasons changed, sand dunes would migrate in and out of the wetter areas where the dinosaurs spent most time.

Dilophosaurus had very distinctive jaws. Its upper jaw had a big notch that created a sizeable tooth gap.

Originally, scientists thought that the jaws would be quite weak due to this tooth gap. They imagined that Dilophosaurus only hunted smaller prey animals. Other experts suggested that it could have eaten fish due to similarities to other reptiles with this diet.

Later studies indicate that Dilophosaurus had stronger jaws than was first thought. There's some evidence it preyed on a four-legged, plant-eating dinosaur called Sarahsaurus.

Either way, Dilophosaurus had quite a light build and was probably very good at running down prey. For this reason, most researchers think it was likely an active hunter rather than a scavenger.

It's unclear whether Dilophosaurus had feathers.

There are fossil footprints that may show evidence of them. But some scientists argue that the footprints don't belong to Dilophosaurus and that the 'feathers' could be something else.

We'll have to wait for more evidence to know for sure.