How much weight could one of the biggest-ever dinosaur predators have lifted in its jaws? And could two of them have carried the 1.9-tonne sauropod shown in the picture above?
These were questions that palaeontologist Donald Henderson of the Royal Tyrrell Museum of palaeontology in Drumheller, Alberta, sought to answer after seeing this artistic rendition.
The picture shows two members of the species Carcharodontosaurus saharicus – theropod relatives of Tyrannosaurus rex – carrying each end of a young plant-eating sauropod. Called "Double Death", the illustration appeared in Dinosaur Art: The World's Greatest Paleoart.
Its creator, UK palaeoartist Bob Nicholls, says his idea for the digital painting came from seeing a pair of male blackbirds (Turdus merula) flying away from a feeding table while holding onto the same mealworm near sunset.
Giant killer birds
Considering the birds as avian dinosaurs, he scaled up the image to show a pair of six-tonne C. saharicus lifting a 1.9-tonne subadult sauropod called Rayosaurus tessonei about 100 million years ago.
Stretching about 10 metres from its head to the tip of its tail, the prey was long enough for both predators to grab hold of with their massive 1.6-metre-long jaws.
The picture looks impressive – but would it have been possible?
Henderson calculated the predators' centre of mass with and without the load to see if they could have balanced while holding the prey in front of them. Fossilised tracks show that massive dinosaurs took smaller steps than lesser-sized ones, so he assumed the predators would have taken small steps to balance the load and keep from tipping forward.
He found that the dinosaurs were massive enough to allow each to balance while holding up to 2.5 tonnes, so two could have done so easily with their hapless prey – and even holding a 5-tonne elephant, had there been any at the time.
But he found that lifting the prey up would have been much harder. Doing this would require powerful neck muscles to hoist the prey and powerful jaw muscles to clamp it in place, Henderson says.
He calculated that the jaw muscles of a C. saharicus could hold 512 kilograms, but its neck muscles could only lift 424 kg. The pair could therefore only have picked up 850 kg between them – about the weight of a large cow or a large crocodile.
So what does that mean for the painting? "The basic story is fine, but we should make the prey item smaller," says Henderson. Nicholls did just that by downsizing the prey to a smaller and younger sauropod in a new version of the painting.
In reality, though, it's unlikely that these two big predatory dinosaurs would have cooperated.
"Most birds tend to be solitary hunters," says Henderson, and he thinks that their non-avian cousins would have done the same – or squabbled over dinner if another predator arrived on the scene.