Hunting on land, Spinosaurus is also forced into direct competition
with any large predators living in the same environment.
And here, that can only mean one animal...
Carcharodontosaurus.
Contests over carcasses are common.
But outcomes of such fights are far from guaranteed.
Risk of injury for big animals is acute.
Modern Komodo dragons are often killed in fights over carcasses.
More than three metres longer, Spinosaurus has size and power on its side.
But Carcharodontosaurus has the more lethal bite.
This time, the Spinosaurus triumphed.
But the balance of power between these two deadly killers
is a precarious one.
In 2008, a Spinosaurus vertebra was recovered.
Part of the tall, neural spine
of the bone was broken off.
It appeared to have been bitten in half.
It's been suggested that the bite was inflicted by Carcharodontosaurus.
Spinosaurus was the last and the largest of the fish-eating dinosaurs.
But ultimately, these specialists were doomed.
Something way beyond their control caused their downfall.
Ninety-four million years ago, the climate changed.
Global sea levels began to rise.
The swamps and rivers that Spinosaurus thrived in gradually were lost.
With their loss, Spinosaurus's specialism became a vulnerability.
And the biggest predator ever known to have walked the Earth disappeared.