Six million years ago, Argentina was ruled by ‘terror birds’. These giant flightless hunters, standing one to three metres tall were at the top of the food chain and killed using a massive, hooked beak, up to two feet in length. The murderous beaks are certainly evocative, but they were no blunt instruments. They were precision weapons, used with finesse and wielded with speed and agility.

Federico Degrange analysed the skull of a medium-sized terror bird called Andalgalornis and found that it was  incredibly strong when biting straight down, but far weaker when being shaken from side to side.  If the bird tried to subdue a struggling victim, its beak would probably have snapped under the strain. So despite its