A true caudal fin or not? New insights in the evolution of the gadiform caudal fin

Abstract The distinctive caudal-fin skeleton of gadiforms has puzzled scientists for a long time, because its many differences in comparison to other teleosts. Contradicting hypotheses interpreted this structure as (i) highly derived teleostean caudal fin, (ii) new formation with parts from the caudal, dorsal and anal fins, so called pseudocaudal, or (iii) complete evolutionary novelty, neocaudal. To shed light on issue, ontogeny Lota lota was studied detail. It differs development non-gadiform taxa, e.g. by absence distinct early notochord flexion. However, there are also similarities teleosts, fin develops before fins. Furthermore, morphology adult fins all major gadiform families were reviewed. Our results, combination latest molecular phylogenies, allowed us discuss evolution resolve origin debated character complex. Although their shows several apomorphies, is homologous without principal inclusion dorsal- anal-fin elements.