Symmoriida

Live reconstruction of Symmorium sp.

The Symmoriida are an extinct group haiartiger cartilaginous fish, whose fossil remains have been found in marine sediments of the upper Paleozoic.

Features

The fish are similar to the Cladoselachia. As these lacked the Symmoriida the anal fin, its tail fin was forked and also externally symmetrical. The pectoral fins were pulled whip-like. In contrast to the Cladoselachia they only had a dorsal fin, which was above the pelvic fins, and no normally developed spines. Her teeth were cladodont. The Symmoriida were beschuppt only along the lateral line organ. The Klaspern were already well developed, but differed from those of modern sharks.

Subtaxa

• Symmoriidae without spines.
• Falcatidae, dorsal fin spine of the males is formed into a forward-facing hook-shaped body with dental occupied surface.
• Stethacanthidae, dorsal fin spine of the males is formed into a brush-shaped body with dental occupied surface.