The tetrapod limb is derived from a posterior part of the fin endoskeleton of elasmobranchs and basal bony fish, the so-called metapterygium, a series of endoskeletal elements that is the first to form in the developing paired fins. (...) In addition, there is an independent endoskeletal element called the protopterygium that develops anterior to the metapterygium in many basal fishes (e.g., the bichir and sturgeon). Teleosts have lost the metapterygium whereas the sarcopterygians, on the other hand, have lost the protopterygium. Sarcopterygians thus develop all their endoskeletal structures from the metapterygium and consequently the tetrapod limb skeleton is derived from the metapterygium.[uncertain][VHOG]

Genes: In limb buds of chick and mouse, Shh expression is activated as soon as there is a morphological bud, whereas in S. canicula fin buds, consistent with reported data in other cartilaginous fishes, Shh is transcribed late in fin development[PMID:17187056]

uberon

UBERON:0004357

• paired limb/fin field

• paired limb/fin

• apical ectodermal ridge
• paired limb/fin bud mesenchyme