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 ...

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 ...

Because all later land vertebrates, or tetrapods, can be traced back to a fish. This encompasses not only amphibians, reptiles and birds, but also mammals—humans included. Yet one mystery ...