Ischyodus

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Ischyodus
Fossil range: Middle Jurassic to Paleocene
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Holocephali
Order: Chimaeriformes
Family: Callorhynchidae
Genus: Ischyodus
Species

Ischyodus bifurcatus
Ischyodus rayhaasi
Ischyodus dolli
Ischyodus rayhassi

Ischyodus is an extinct genus of cartilaginous fish belonging to the subclass Holocephali, which includes the modern-day chimaeras.

Ischyodus was virtually identical to the present-day chimaera Chimaera monstrosa, which is found in the Atlantic Ocean and Mediterranean Sea. Just like C. monstrosa, Ischyodus had large eyes, a long whip-like tail, small lips, large pectoral fins and dorsal fin, and a poisonous dorsal spike attached to the front of the dorsal fin. The spike probably served as a method of protection against predators.

Dental plates have been found at several sites in North Dakota