Fin ray patterns at the fin-to-limb transition.

The fin-to-limb transition was marked by the origin of digits and the loss of dermal fin rays. Paleontological research into this transformation has focused on the evolution of the endoskeleton, with little attention paid to fin ray structure and function. To address this knowledge gap, we study the dermal rays of the pectoral fins of 3 key tetrapodomorph taxa- (Rhizodontida), (Tristichopteridae), and (Elpistostegalia)-using computed tomography.