CORONARY-ARTERY ANATOMY AND ELASMOBRANCH PHYLOGENY

The anatomical arrangements of the coronary arteries were compared in 36 species from eight orders of elasmobranchs and one species of holoc ephalians, Two main patterns of the coronary trunks are defined in the conus arteriosus. A dorsal and a ventral coronary trunk are present i n lamnoid and carcharhinoid representatives (except in scyliorhinids), while two lateral coronary trunks are always observed in the holoceph alian, hexanchoid, squaloid, squatinoid, scyliorhinid and batoid repre sentatives. Posterior coronary arteries arising from subclavian branch es are recorded only in rajoid and myliobatoid specimens. We propose t hat both the dorsoventral coronary trunk pattern and the presence of p osterior coronary arteries are apomorphic. Thus, the phylogenetic anal ysis of these character-states supports the view that lamnoids are the sister-group of advanced carcharhinoids (carcharhinids and sphyrnids) , sharing the dorsoventral coronary trunk pattern as a synapomorphy.