Dwykaselachus

Dwykaselachus Temporal range: Guadalupian PreꞒ Ꞓ O S D C P T J K Pg N (Middle Permian)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Order:	†Symmoriiformes
Genus:	†Dwykaselachus Oelofsen, 1986
Type species
†Dwykaselachus oosthuizeni Oelofsen, 1986

Dwykaselachus (pronounced dwike-a-selak-us) is an extinct genus of symmoriiform, a cartilaginous fish that lived in what is now South Africa during the Permian period around 280 million years ago. It was first discovered in the 1980s, in a nodule of sediments from the Karoo Supergroup. Dwykaselachus was named based on Dwyka Group, the group of sedimentary geological formation in the southeastern part of Africa. It represents the place where the type species Dwykaselachus oosthuizeni was found.^[1]

Prior to its discovery, symmoriiforms were thought to be related to sharks, in the group Elasmobranchii. However, CT scans of its relatively intact skull showed traits such as brain shape and inner ear structure that are shared with cartilaginous fish from the group Holocephali, which includes chimaeras.^[2] This implies that the first major radiation of cartilaginous fish after the Devonian extinction was in fact holocephalians, rather than sharks as commonly believed.^[3]