Dictionary.net

• A sub-family of extinct sharks.

1914 - Nuttall's Standard dictionary of the English language
By Nuttall, P.Austin.

• In geol., a family of fossil shark-like fishes furnished with teeth having knobbed crowns.

1874 - Etymological and pronouncing dictionary of the English language
By Stormonth, James, Phelp, P. H.