Symmoriida

Symmoriid Temporal range: 359–294 Ma PreЄ Є O S D C P T J K Pg N
Symmorium
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Subclass:	Holocephali
Order:	Symmoriida Zangerl, 1981
Families
Symmoriidae Falcatidae Stethacanthidae

Symmoriidae
Falcatidae
Stethacanthidae

Symmoriida is an extinct order of ratfish that contains three families. It was synonymized subjectively with Cladodontida by Lund (1986); it was corrected as Symmoriiformes by Maisey (2008). It was assigned to Cladoselachii by Goto et al. (1988); to Elasmobranchii by Williams (1998); and to Chondrichthyes by Sepkoski in 2002 and by Maisey in 2008. In the fossil record they appear at the beginning of the Carboniferous. Most of them died out at the start of the Permian; however, a single tooth described by Guinot et al. (2013) from the Valanginian of France indicates that members of the family Falcatidae might have survived until the Early Cretaceous.

Fossil evidence of Symmoriida have been found at Bear Gulch, Fergus County, Montana, Bethel Quarry, Pike County, Indiana, Kinshozan quarry, Alaska, Gifu Prefecture, Japan, and Bashkortostan, Russian Federation.