Kinosternoidea

Kinosternoidea is an obsolete superfamily of aquatic turtles, which included two families: Dermatemydidae (Mesoamerican River Turtles), and Kinosternidae (American mud and musk turtles). Sometimes, even the entirely unrelated Big-headed Turtle ("Platysternon megacephalum") was included with the "kinosternoids" too.

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