The common ancestor of Panderichthys and tetrapods evolved the rudiments
of ribs. The shoulder differed from that of tetrapods in that the glenoid
cavity was smaller and more medial and the scapulocoracoid was bigger.
The ulna had increased in size in these fish and was intermediate between
earlier fish and tetrapods. The fin rays were still composed of dermal
bone, unlike the endochondral bone which would compose tetrapod digits
(Clark, 2002). The fin of Panderichthys is depicted below with bones homologous
to those of tetrapods (such as the huerus in blue, radius in red, and
ulna in green).