What is "trionychia"

Trionychia is a superfamily of turtles which encompasses the species that are commonly referred to as softshelled turtles as well as some others. They are found throughout the temperate regions of the world.

It traditionally consisted of a single family, two subfamilies, and 14 genera. However, more recently it was realized that the supposed " Kinosternoidea" are actually early offshoots of the Trionychoidea and not as closely related among each other as it was believed. These two families lack the characteristic trionychoid apomorphies, but possess some highly derived characters of their own, which they moreover evolved independently from each other.