- Testudines
Taxobox
name = Turtles
fossil_range = Fossil range|210|0Late Triassic - Recent
image_width = 240px
image_caption = "Chelonia" fromErnst Haeckel 's "Kunstformen der Natur ", 1904
regnum =Animal ia
phylum =Chordata
subphylum =Vertebrata
superclassis =Tetrapoda
classis =Reptilia
subclassis =Anapsida
superordo = Chelonia
superordo_authority = Macartney, 1802
ordo = Testudines
ordo_authority = Linnaeus, 1758
range_
range_map_width = 240px
range_map_caption = blue: sea turtles, black: land turtles
diversity_link= List of Testudines families
diversity= 14 extant families with ca. 300 species
subdivision_ranks = Suborders
subdivision =Cryptodira Pleurodira See text for families.Turtle s,Tortoise s, andTerrapin s are ectothermicreptile s, most of whosebody is shielded by a special bony orcartilage nous shell developed from theirrib s. They belong to ananapsid lineage, as can be seen from their solid skullcap. About 300species are alive today; some are highly endangered.The order to which the turtles belong is usually called Testudines. Sometimes Chelonia is given as a
junior synonym , but this is strictly speaking incorrect. For most purposes, the differences are minor however: The Chelonia are simply the Testudines plus the "proto-turtle" "Australochelys africanus ", a turtlelike anapsid from theJurassic which lacked some of the Testudines'apomorph ies. The oldest fossils of the Testudines actually predate "Australochelys". They are the basal turtlegenus "Proganochelys " [Formerly known as "Triassochelys"] which lived inLate Triassic Eurasia about 210million years ago, making turtles one of the oldest reptile groups, and a much more ancient group thanlizard s andsnake s.Characteristics
The defining feature of the testudines is the presence of a bony shell comprising an upper
carapace and a lowerplastron , both composed of solid bony plates. In most families, this bony shell is further covered by a layer of thick horny scales, which form the visible part of the shell, but some have a softer, leathery, coveringcite book |editor=Cogger, H.G. & Zweifel, R.G.|author= Obst, Fritz Jurgen|year=1998|title=Encyclopedia of Reptiles and Amphibians|publisher= Academic Press|location=San Diego|pages= 108-111|isbn= 0-12-178560-2] .Living testudines lack teeth, having a horny beak, which is sharpened or serrated to cut flesh or plant matter. Testudines also have strong limbs to lift their heavy bodies. The shape of the limb is variable, however, with land dwelling species typically fusing the toes into a solid clump, freshwater species having distinct, but webbed, toes, and marine species having powerful flippers.
Testudines lay eggs in a nest chamber, but no species displays parental care. Instead, the young are left to fend for themselves from the moment they hatch. Incubation time varies greatly between species, but two to three months is typical.
ystematics
There are about 300 living species of testudine, grouped into two suborders and fourteen families [See references in Haaramo (2008)] .
Basal chelonians
* Genus "
Australochelys " (basal Chelonia)
* Genus "Proganochelys " (basal Testudines)uborder
Cryptodira Basal genera
* Genus "Kayentachelys "
* Genus "Indochelys "Infraorder †Paracryptodira
*Basal and "incertae sedis "
**Family †Kallokibotiidae
**Family †Mongolochelyidae
**Family †Pleurosternidae
**Family †Solemydidae
*Superfamily †Baenoidea
**Family †Baenidae
**Family †Macrobaenidae
**Family †Neurankylidae InfraorderEucryptodira
* †"Sinemys" wuerhoensis"
* Genus †"Chubutemys " (Meiolaniidae?)
* Genus †"Hangaiemys " (Macrobaenidae?)
* Genus †"Judithemys "
* Genus †"Osteopygis "
* Genus †"Planetochelys "
* FamilyChelydridae (snapping turtles)
* Family †Eurysternidae
* Family †Macrobaenidae
* Family †Meiolaniidae (horned turtles)
* Family †Plesiochelyidae
* Family †Sinemydidae
* Family †Xinjiangchelyidae
*SuperfamilyChelonioidea (sea turtles)
**Family †Protostegidae
**Family †Thalassemyidae
**Family †Toxochelyidae
**FamilyCheloniidae (green sea turtles and relatives)
**FamilyDermochelyidae (leatherback turtles)
*SuperfamilyTestudinoidea
**Family †Haichemydidae
**Family †Lindholmemydidae
**Family †Sinochelyidae
**FamilyPlatysternidae (big-headed turtle)
**FamilyEmydidae (pond, box andwater turtle s)
**FamilyGeoemydidae (Asian river turtle s,Asian leaf turtle s,Asian box turtle s androofed turtle s)
**FamilyTestudinidae (tortoises)
*SuperfamilyTrionychoidea
**Family †Adocidae
**FamilyCarettochelyidae (pignose turtles)
**FamilyDermatemydidae (river turtles)
**FamilyKinosternidae (mud turtles)
**FamilyTrionychidae (softshell turtles)uborder
Pleurodira Basal and "incertae sedis"
*Family †Araripemydidae
*Family †Proterochersidae
*FamilyChelidae (Austro-American sideneck turtles)SuperfamilyPelomedusoidea
*Family †Bothremydidae
*FamilyPelomedusidae (African sideneck turtles)
*FamilyPodocnemididae (Madagascan big-headed andAmerican sideneck river turtle s)Footnotes
References
* (2008):
Mikko's Phylogeny Archive - [http://www.helsinki.fi/~mhaaramo/metazoa/deuterostoma/chordata/reptilia/parareptilia/hallucicrania.html Hallucicrania] . Version of 2008-MAR-11. Retrieved 2008-MAY-07.
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