What is "kinosternoidea"

Kinosternoidea is a superfamily of aquatic turtles, which included two families: Dermatemydidae, and Kinosternidae.

These are nowadays usually considered independent families of the Trionychia, among which they represent very plesiomorphic members which share a few peculiarly advanced traits. These apomorphies coupled with the overall "primitiveness" was what misled scientists as to their actual relationships.