Testudinata

Amazon river turtle Podocnemis expansa, from here.

Belongs within: Lepidosauromorpha.
Contains: Cryptodira, Chelidae.

The Testudinata are the turtles and tortoises, a clade of reptiles unmistakeable through the enclosure of the body in a bony shell. The shell incorporates the ribcage of the animal, and the shoulder girdle has become enclosed within the ribcage. The relationships of testudinates to other reptiles remain rather uncertain due to their highly modified anatomy. The most commonly supported views are a relationship to the anapsid procolophonians or to the diapsid sauropterygians.

The earliest known turtles come from the Late Triassic (Middle Triassic if the fragment Priscochelys comes from a testudinate) with the basalmost testudinate Odontochelys lacking a developed carapace, though the plastron was already present (Li et al. 2008). As well as the presence of a carapace, testudinates other than Odontochelys are united by the absence of teeth on the maxilla, premaxilla and dentary, which are covered by a horny beak (Gaffney & Meylan 1988). The Late Triassic Proganochelys retained a series of flattened teeth on the roof of the mouth. More derived testudinates, the Casichelydia, are also united by the absence of the lacrimal bone and duct, the basipterygoid articulation being fused, presence of a single vomer, presence of a lateral and ventral wall to the middle ear, and having the paroccipital process tightly sutured to the braincase (Gaffney & Meylan 1988).

The turtle crown group (Testudines) is divided between two major lineages, the Cryptodira and Pleurodira, with the former being more diverse. The Pleurodira are mostly restricted to the Southern Hemisphere; members of this lineage are able to retract their head within the shell by bending the neck horizontally to one side.

<==Testudinata [Chelonia, Proganochelydia]
    |--Odontochelys Li, Wu et al. 2008 [Odontochelyidae] LW08
    |    `--*O. semitestacea Li, Wu et al. 2008 LW08
    `--+--Proganochelys Baur 1887 LW08, D07
       |    `--P. quenstedti GM88
       `--Casichelydia GM88
            |--Proterochersis LW08
            |--Palaeochersis LW08
            `--Testudines LW08
                 |--Cryptodira GM88
                 `--Pleurodira GM88
                      |  i. s.: Hydromeda tectifera H04
                      |         Araripemys Price 1973 D07
                      |           `--A. barretoi D07
                      |--Platychelys GM88
                      `--Eupleurodira GM88
                           |--Chelidae GM88
                           `--+--Pelomedusidae [Pelomedusinae] AS09
                              |    |--+--Taphrosphys GM88
                              |    |  `--Bothremys GM88
                              |    `--+--Pelomedusa subrufa GM88
                              |       `--Pelusios williamsi GM88, AS09
                              `--Podocnemididae [Podocneminae] AS09
                                     |--+--Shweboemys GM88
                                     |  `--Stereogenys GM88
                                     `--+--Erymnochelys GM88
                                        `--+--Peltocephalus GM88
                                           `--Podocnemis GM88
                                                |--P. expansa DS86
                                                |--P. sextuberculata DS86
                                                `--P. unifilis DS86

Testudinata incertae sedis:
  Plastomenus Cope 1872 C77
    |--P. communis Cope 1875 C77
    |--P. corrugatus Cope 1875 C77
    |--P. fractus Cope 1875 C77
    |--P. lachrymalis Cope 1874 C77
    |--P. multifoveatus Cope 1872 [incl. P. catenatus Cope 1875] C77
    |--P. oedemius C77
    |--P. serialis Cope 1876 C77
    |--P. thomasii C77
    `--P. trionychoides C77
  Scaptochelys agassizii AA87
  Anglocetus beatsoni Tarlo 1964 BM78
  Kallokibotion [Kallokibotiidae] PST99
    `--K. bajazidi Nopcsa 1923 PST99
  Cheirogaster gymnesica Bate 1914 RB05, BG-PQ-C02
  Ptychogaster RB05
  Solnhofia GM88
  Cylindraspis FS01
    |--C. indica FS01
    |--C. inepta FS01
    |--C. peltastes FS01
    |--C. triserrata FS01
    `--C. vosmaeri FS01
  Sandowina LW08
  Mongolemys LW08
  Australochelys LW08

*Type species of generic name indicated

REFERENCES

[AS09] Alfaro, M. E., F. Santini, C. Brock, H. Alamillo, A. Dornburg, D. L. Rabosky, G. Carnevale & L. J. Harmon. 2009. Nine exceptional radiations plus high turnover explain species diversity in jawed vertebrates. Proceedings of the National Academy of Sciences of the USA 106 (32): 13410–13414.

[AA87] Avise, J. C., J. Arnold, R. M. Ball, E. Bermingham, T. Lamb, J. E. Neigel, C. A. Reeb & N. C. Saunders. 1987. Intraspecific phylogeography: the mitochondrial DNA bridge between population genetics and systematics. Annual Review of Ecology and Systematics 18: 489–522.

[BG-PQ-C02] Bailon, S., J. Garcia-Porta & J. Quintana-Cardona. 2002. Première découverte de Viperidae (Reptilia, Serpentes) dans les îles Baléares (Espagne): des vipères du Néogène de Minorque. Description d’une nouvelle espèce du Pliocène. Comptes Rendus Palevol 1: 227–234.

[BM78] Barnes, L. G., & E. Mitchell. 1978. Cetacea. In: Maglio, V. J., & H. B. S. Cooke (eds) Evolution of African Mammals pp. 582–602. Harvard University Press: Cambridge (Massachusetts).

[C77] Cope, E. D. 1877. Report upon the extinct Vertebrata obtained in New Mexico by parties of the expedition of 1874. Geographical Surveys West of the One Hundredth Meridian 4 (2): i–iv, 1–370.

[D07] Dixon, D. 2007. The Complete Illustrated Encyclopedia of Dinosaurs & Prehistoric Creatures. Hermes House: London.

[DS86] Dixon, J. R., & P. Soini. 1986. The Reptiles of the Upper Amazon Basin, Iquitos Region, Peru. Milwaukee Public Museum: Milwaukee.

[FS01] Flannery, T., & P. Schouten. 2001. A Gap in Nature: Discovering the World's Extinct Animals. Text Publishing: Melbourne.

[GM88] Gaffney, E. S., & P. A. Meylan. 1988. A phylogeny of turtles. In: Benton, M. J. (ed.) The Phylogeny and Classification of the Tetrapods vol. 1. Amphibians, Reptiles, Birds pp. 157–219. Clarendon Press: Oxford.

[H04] Haeckel, E. 1899–1904. Kunstformen der Natur. Bibliographisches Institut: Leipzig und Wien.

[LW08] Li, C., X.-C. Wu, O. Rieppel, L.-T. Wang & L.-J. Zhao. 2008. An ancestral turtle from the Late Triassic of southwestern China. Nature 456: 497–501.

[PST99] Pereda Suberbiola, X., & P. Taquet. 1999. Restes de Rhabdodon (dinosaure ornithopode) de Transylvanie donnés par Nopcsa au Muséum national d'Histoire naturelle de Paris. Geodiversitas 21 (2): 157–166.

[RB05] Rage, J.-C., & S. Bailon. 2005. Amphibians and squamate reptiles from the late early Miocene (MN 4) of Béon 1 (Montréal-du-Gers, southwestern France). Geodiversitas 27 (3): 413–441.

Last updated: 11 August 2017.