Kinosternoidea is a superfamily

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 of aquatic turtle

Turtle

Turtles are reptiles of the order Testudines , characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield...

s, which included two families: Dermatemydidae, and Kinosternidae

Kinosternidae

Kinosternidae is a family of mostly small turtles that includes the mud turtles and musk turtles. The family Kinosternidae contains 25 species within 4 genera, but taxonomic reclassification is an ongoing process so many sources vary on the exact numbers of species and subspecies...

.

These are nowadays usually considered independent families

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 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 mislead scientists as to their actual relationships.

Classification

• Dermatemydidae family

• Dermatemys genus

• Kinosternidae
  Kinosternidae
  Kinosternidae is a family of mostly small turtles that includes the mud turtles and musk turtles. The family Kinosternidae contains 25 species within 4 genera, but taxonomic reclassification is an ongoing process so many sources vary on the exact numbers of species and subspecies...
  
   family
• Kinosterninae
  Kinosterninae
  Kinosterninae is a subfamily of the Kinosternidae family of aquatic turtles which contains the genera Kinosternon and Sternotherus, which are native to much of the United States and northern Mexico.- References :*...
  
   subfamily

• Kinosternon
  Kinosternon
  Kinosternon is a genus of aquatic turtles known commonly as mud turtles.-Geographic range:They are found throughout the United States, Mexico and Central America, south into South America in Colombia, Ecuador and northern Peru.-Description:...
  
   genus
• Sternotherus
  Sternotherus
  Sternotherus is a genus of aquatic turtles known commonly as musk turtles.-Description:They are very similar to the American mud turtles, but tend to have a more domed carapace, with a distinctive keel down the center of it...
  
   genus

• Staurotypinae
  Staurotypinae
  Staurotypinae is a subfamily of the Kinosternidae family of aquatic turtles which contains the genera Claudius and Staurotypus....
  
   subfamily

• Claudius genus
• Staurotypus
  Staurotypus
  Staurotypus is a genus of aquatic turtles commonly known as Mexican musk turtles, giant musk turtles, or three-keeled musk turtles...
  
   genus

Past classification

The entirely unrelated Big-headed Turtle

Big-headed Turtle

The big-headed turtle is a species of turtle in the family Platysternidae.-Background:Previously considered a distinct family placed on occasion in "Kinosternoidea", it was later moved to the Emydidae. With the Geoemydidae being split off from these, it seems wisest to reinstate, at least for the...

(Platysternon megacephalum) was included.