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Cryptodira

(Suborder)

Overview

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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 necks and pull the heads straight back into the shells; instead of folding their necks sideways along the body under the shells' margins. They include among their species freshwater turtles, snapping turtles, tortoises, soft shell turtles, and sea turtles.

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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 pond turtles) 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 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

Manchurochelys liaoxiensis was a paracryptodire.
Meiolania platyceps was a primitive eucryptodire.
Kinixys belliana from the Testudinidae
The Indian Flap-shelled Turtle (Lissemys punctata) from the Trionychidae is a highly advanced eucryptodire


See also

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Footnotes

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  1. ^ a b c d See references in Haaramo (2008)
b>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 necks and pull the heads straight back into the shells; instead of folding their necks sideways along the body under the shells' margins. They include among their species freshwater turtles, snapping turtles, tortoises, soft shell turtles, and sea turtles.

[ Back to top ]

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 pond turtles) 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. Th ese are, in turn, made up from some very basal groups, and the Centrocryptodira 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

Manchurochelys liaoxiensis was a paracryptodire.
Meiolania platyceps was a primitive eucryptodire.
Kinixys belliana from the Testudinidae
The Indian Flap-shelled Turtle (Lissemys punctata) from the Trionychidae is a highly advanced eucryptodire


See also

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Footnotes

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

References

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Taxonomy

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The Suborder Cryptodira is a member of the Order Testudines. Here is the complete "parentage" of Cryptodira:

The Suborder Cryptodira is further organized into finer groupings including:

Families

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Adocidae

[more]

Baenidae

[more]

Bataguridae

Geoemydidae (formerly known as Bataguridae) is the largest and most diverse family[] in the order Testudines (turtles) with about 70 species. It includes the Eurasian pond and river turtles and Neotropical wood turtles. [more]

Carettochelyidae

The pig-nosed turtle (Carettochelys insculpta), also known as the pitted-shelled turtle or fly river turtle, is a species of turtle native to freshwater streams, lagoons and rivers of Australia and New Guinea. This species is the only living member of the genus Carettochelys, the subfamily Carettochelyinae and the family Carettochelyidae; however, numerous extinct carettochelyid species have been described from all over the world. [more]

Cheloniidae

Cheloniidae is a family of turtles belonging to the sea turtle superfamily Chelonioidea. [more]

Chelydridae

Chelydridae is a family of turtles which has seven extinct and two extant genera. The extant genera are Chelydra the snapping turtles, and its larger relative Macrochelys, of which the Alligator Snapping Turtle (Macrochelys temminckii) is the only species. Both are endemic to the Western Hemisphere. The extinct genera are Acherontemys, Chelydrops, Chelydropsis, Emarginachelys, Macrocephalochelys, Planiplastron, and Protochelydra. [more]

Dermatemydidae

The Central American river turtle or Mesoamerican river turtle (Dermatemys mawii) locally known as the "hickatee" or "tortuga blanca"-(white turtle) is the only living species in the family Dermatemydidae. Its closest relatives are only known from fossils [more]

Dermochelyidae

Dermochelyidae is a family of turtles which has eight extinct and one extant genera. [more]

Emydidae

Emydidae, commonly called the pond turtles or marsh turtles, is a family of turtles. Previously, several species of Asian box turtle were classified in the family. However, revised taxonomy has separated them to a different family. Now, Emydidae, with the exception of two species of pond turtle, is entirely a Western Hemisphere family. The family Emydidae includes close to 50 species in 10 genera. [more]

Glyptopsidae

[more]

Kayentachelyidae

[more]

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. They inhabit slow-moving bodies of water, often with soft, muddy bottoms and abundant vegetation. [more]

Meiolaniidae

[more]

Plesiochelyidae

[more]

Protostegidae

[more]

Solemydidae

[more]

Testudinidae

Tortoises (, Testudinidae) are a family of land-dwelling reptiles of the order of turtles (Testudines). Like their marine cousins, the sea turtles, tortoises are shielded from predators by a shell. The top part of the shell is the carapace, the underside is the plastron, and the two are connected by the bridge. The tortoise has both an endoskeleton and an exoskeleton. Tortoises can vary in size from a few centimeters to two meters. Tortoises are usually diurnal animals with tendencies to be crepuscular depending on the ambient temperatures. They are generally reclusive animals. [more]

Toxochelyidae

[more]

Trionychidae

Trionychidae is a taxonomic family which comprises a number of turtle genera commonly known as softshells. They are also sometimes called pancake turtles. Softshells consist of some of the world's largest fresh water turtles, though many can adapt to living in highly brackish areas. Members of this family occur in Africa, Asia, North America, and Southeast Asia. North American members of genus Trionyx were fairly recently (1987) assigned the resurrected genus name Apalone by Meylan, though they are still listed semi-correctly as Trionyx in some texts. [more]

At least 196 species and subspecies belong to the Family Trionychidae.

More info about the Family Trionychidae may be found here.

References

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Footnotes

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

Further Reading

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Sources

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Last Revised: August 24, 2012
2012/08/24 13:16:45