There's nothing magical about the number, yet five digits at the end of their limbs is a motif that runs through all the animals with four limbs, called tetrapods. Even when there are fewer than ...

The researchers focused on tetrapods — vertebrates with four legs. They investigated more than 33,000 species worldwide and identified 25 priority tetrapod EDGE Zones across 33 countries.

It was found very close to the shoulder girdle, and it has many of the features that are distinctive of early tetrapod lower jaws. What's really neat about it is it's a very skinny jaw -- it's ...