An article published in the journal “Science Advances” reports a study on the evolution of the forelimbs’ skeleton and muscles in the transition from fish to tetrapods. A team of researchers led by Julie Molnar of the New York Institute of Technology and Stephanie Pierce of Harvard examined three-dimensional models of the bones, joints, and muscles of the fins and limbs of two now-extinct early tetrapods and a fish closely related to them. The conclusion is that those early tetrapods had anatomical features more suited to propulsion than to support their weight.