Sarcopterygian fish are united by having a fleshy lobe at the base of their paired fins, containing bones covered in muscle. Each of the two pairs of fins is attached to the shoulder or pelvic girdle by a single bone, the humerus in the front pair, and the femur in the back pair. The lobe fin fishes are arguably the most successful group of vertebrates on Earth, although few of their descendants remain as fishes. The only extant fishes of this group are two species of coelacanth and six species of lungfish, whereas most lobe-fin fish descendants are land living vertebrates, including mammals, amphibians and reptiles (including birds)! These latter are descended from a group of lobe fin fishes, the Tetrapodomorpha (1). Towards the end of the Devonian, four legged fishes appeared, having variable numbers of fingers and toes and the ability to breathe air. These digitate tetrapods were the prototype for the first land living vertebrates.
Two species of digitate tetrapod have been described from Waterloo Farm on the basis of isolated bones. Other lobe-fin fishes recorded at the site include a species of coelacanth, a lungfish and a gigantic tristichopterid fish. References; 1) Clack J. A., (2012). Gaining ground: the origin and evolution of tetrapods. Indiana University Press. |