Palaeontologists in Argentina believe they have found bones belonging to the heaviest dinosaur to ever have walked the Earth - which had an estimated body mass of 77 tonnes.

They found bones belonging to seven individuals from a new species of titanosaur, which has yet to be named - and calculated the approximate size of the largest one by measuring the diameter of the femur and the humerus bones.

In this video, Dr Diego Pol explains how the measuring process works. A film crew from the BBC Natural History Unit filmed him and Dr Jose Luis Carballido when they measured the femur.