†family Helodontidae (chimaera)
Chondrichthyes - Helodontiformes - Helodontidae
Parent taxon: Helodontiformes according to J. S. Nelson 2006
See also Zangerl 1981
Sister taxa: none
Subtaxa: Helodus
Ecology: nektobenthic carnivore
Distribution:
• Permian of Australia (1 collection), Greenland (1), Lithuania (1), United States (6: Oklahoma, Wyoming)
• Pennsylvanian of the United Kingdom (1)
• Chesterian of Canada (1: Alberta)
• Carboniferous of the United Kingdom (3), United States (3: Arizona, Illinois, Nebraska)
• Mississippian of the United Kingdom (1), United States (1: Indiana)
• Devonian of Australia (1)
Total: 20 collections including 25 occurrences