Fossils and Strata


Jessen, H. L.: Schultergürtel und Pectoralflosse hci Actinopterygiern. [Shoulder girdle and pectoral fin in actinopterygians.] Fossils and Strata, Number 1, pp. 1–101, Pls. 1–25. Oslo, 5th May 1972.

The anatomy of the shoulder girdle and pectoral fin is investigated in adults and larvae of Asperser, Amia, Lepisosteus, Elops, Salmo, and Polypterus. In comparison with similar structures in other gnathostomian fishes these studies yielded certain conclusions as concerns the interrelationships of the recent actinopterygian groups and the affinities of the hrachiopterygians, the latter by this evidence belonging to an evolutionary line of their own. With regard to actinopterygian phylogeny, a comparison with the shoulder girdle and pectoral fin in fossil forms, including Chondrosteus, Moythomoasia, Palaeoniscus, Pteronisculus, Pachycormus, Catarus, Hypsocormus, and Birzeria, shows that teleosteans presumably are closer to chondrosteans than holosteans, and that holosteans seem to have branched off comparatively early from the actinopterygian stem.