To make this genetic tweak, Bhullar and his colleagues isolated the proteins that would have gone on to develop beaks. Then they suppressed them using tiny beads coated with an inhibiting substance.

When their skeletons started to develop inside the eggs, these animals had short, rounded bones instead of elongated, fused beaks that bird skeletons have.

“By affecting this early protein you are actually altering gene expression,” added Bhullar.

The work highlights that beaks develop very differently from snouts, using a different set of genes, says Michael Benton of Bristol University in the UK. “That’s what proves the beak is a real adaptation or ‘thing’, not just a slightly different nose shape.”