Cow shark
| Cow sharks Temporal range:  Possible Permian occurrence | |
|---|---|
| Scientific classification | |
| Domain: | Eukaryota | 
| Kingdom: | Animalia | 
| Phylum: | Chordata | 
| Class: | Chondrichthyes | 
| Subclass: | Elasmobranchii | 
| Division: | Selachii | 
| Order: | Hexanchiformes | 
| Family: | Hexanchidae J. E. Gray, 1851 | 
| Genera | |
| See text | |
Cow sharks are a shark family, the Hexanchidae, characterized by an additional pair or pairs of gill slits. Its species are placed within the 11 genera: Gladioserratus, Heptranchias, Hexanchus, Notidanodon, Notorynchus, Pachyhexanchus, Paraheptranchias, Pseudonotidanus, Welcommia, Weltonia, and Xampylodon.