I-Rex, therefore I am: How to make Jurassic World’s new hybrid dinosaur

Dr Robin Andrews

No-one’s interested in dinosaurs anymore, the film seems to say. Jurassic World – the zoo for dinosaurs – has been open for two decades, and seeing dinosaurs has become fairly routine by 2015. In a knowing nod to audiences used to seeing enormous CGI spectacles these days, the scientists in the highly-anticipated summer blockbuster have “cooked up” a new dinosaur to give both the kids and adults nightmares: the Indominus Rex, which means “fierce” or “untameable king”. Move over, T-Rex – the I-Rex is here, and it already sounds like a new line of Apple products. The publicity for the dinosaur has been intentionally ambiguous, only teasing its appearance and behaviour in the trailers. Apart from some leaked merchandising artwork – which incidentally revealed the dinosaur in its entirety – much about the film’s reptilian star has been kept under wraps. So what will it be like?

I have it on good authority (well, from the film’s official website) that this dinosaur was cooked up by geneticists using a mix of at least four other dinosaurs: the Carnotaurus (“meat-eating bull”), the Giganotosaurus (“giant southern lizard”), the Majungasaurus (“Mahajanga lizard”), and the Rugops (the less-chilling sounding “wrinkle face”). All four are meat-eating theropods (“beast feet”), and at least three are top predators.

The Carnotaurus was a large, swift predator with horns on its skull; its extremely powerful leg muscles allowed it to quickly close the gap between any prey unlucky enough to become its target. They were certainly apex predators, enough to fill the ecological niche occupied by the tyrannosaurs in other parts of the ancient world.

The Giganotosaurus was, as you may suspect, quite hefty: its skull was as long as the average British female (1.6m), and its total length was up to 13m. It could run up to 14 metres per second – certainly fast than Usain Bolt at his average record breaking speed of 10.42 metres per second – and had teeth in its lower jaw specialised for inflicting slicing wounds.

The Majungasaurs’ standout feature is its abundance of sharp teeth in both its upper and lower jaws. Its skull shape suggests it bit into its prey once and held it there until it died, unlike other predatory theropods, which gave the prey several life-destroying chomps.

Finally, the Rugops: featuring spines or spikes all along its back as armour, this smaller theropod was likely to be a scavenger.

Having a peek at the leaked artwork, however, reveals one additional feature that none of the above dinosaurs have: extremely long arms with razor-sharp, semi-collapsible claws. This suggests that the I-Rex is capable of lacerating its prey or even picking its prey up in a scooping motion, ready to be chewed on. These arms and claws are more reminiscent of those found on certain Dromaeoaurs, bird-like theropod dinosaurs. In particular, the Deinonychus, a close cousin of the infamous Velociraptor, had very long forelimbs with sickle-like claws, and biomechanical studies infer that these were used for grasping prey.

So, assuming the scariest parts of all of the above are taken by the film’s geneticists and merged into a single I-Rex, we can probably expect an extremely fast predator with very powerful leg muscles, horns or spikes along its head and spine, and a lot of long, sharp teeth, more than most related dinosaurs would have. It is likely to pick up its prey and hold it in its mouth, letting it bleed out before consuming it.

Phew. Chris Pratt’s certainly got his work cut out for him; good thing he’s got a trained pack of Velociraptors to help him out.


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