Cryptodira

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Cryptodira
Fossil range: Jurassic - Recent
Aldabra Giant Tortoise (Dipsochelys dussumieri)
Aldabra Giant Tortoise (Dipsochelys dussumieri)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Superclass: Tetrapoda
Class: Sauropsida
Subclass: Anapsida
Order: Testudines
Suborder: Cryptodira
Infraorders

Paracryptodira
Eucryptodira
and see text
Synonyms

Cryptodiramorpha Lee, 1995

Cryptodira is the taxonomic suborder of Testudines that includes most living tortoises and turtles. Cryptodira differ from Pleurodira (side-neck turtles) in that they lower their neck and pull the head straight back into the shell, instead of folding the neck sideways along the body under the shell's margin.

[edit] Systematics and evolution

Cryptodires evolved primarily through the Jurassic period, and by the end of the Jurassic had almost completely replaced Pleurodires in the lakes and rivers, while beginning to develop land-based species.

Cryptodira has three living superfamilies, the Chelonioidea (sea turtles), Testudinoidea (tortoises) and Trionychoidea (softshell turtles and relatives). The "Kinosternoidea" are now recognized as a paraphyletic assemblage of mostly primitive Trionychoidea; they do not form a natural group.[1]

There are two commonly-found circumscriptions of the Cryptodira. One is used here; it includes a number of primitive extinct lineages known only from fossils, as well as the Eucryptodira. These are in turn made up from some very basal groups and the Centrocryptodira, which contains the prehistoric relatives of the living cryptodires as well as the latter which are collectively called Polycryptodira.[1]

The alternate concept restricts the use of the term "Cryptodira" to the crown clade (i.e. Polycryptodira). The Cryptodira as understood here are called Cryptodiramorpha in this view. Under this approach, the pleurodires and cryptodires are not sister taxa.[1]

As per the system used here, the Cryptodira can be classified as follows:[1]

SUBORDER CRYPTODIRA

  • Basal genera
    • Genus Kayentachelys (fossil; sometimes monotypic family Kayentachelyidae)
    • Genus Indochelys (fossil; sometimes monotypic family Indochelyidae)
Manchurochelys liaoxiensis was a paracryptodire.
Manchurochelys liaoxiensis was a paracryptodire.
  • Infraorder Paracryptodira (fossil)
    • Basal and incertae sedis
      • Family Kallokibotiidae
      • Family Mongolochelyidae
      • Family Pleurosternidae
      • Family Solemydidae
    • Superfamily Baenoidea
      • Family Baenidae
      • Family Macrobaenidae
      • Family Neurankylidae
Meiolania platyceps was a primitive eucryptodire.
Meiolania platyceps was a primitive eucryptodire.
Kinixys belliana from the Testudinidae...
Kinixys belliana from the Testudinidae...
...and the Indian Flap-shelled Turtle (Lissemys punctata) from the Trionychidae are highly advanced eucryptodires.
...and the Indian Flap-shelled Turtle (Lissemys punctata) from the Trionychidae are highly advanced eucryptodires.


[edit] Footnotes

  1. ^ a b c d See references in Haaramo (2008)

[edit] References


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