Common snapping turtle Chelydra serpentina, photographed by M. J. Baker.

Belongs within: Pancryptodira.
Contains: Pantrionychia, Emydidae, Pantestuguria, Kinosternidae, Dermochelyoidae, Cheloniidae.

The clade Centrocryptodira unites the crown cryptodiran tortoises with the extinct Meiolaniidae, the horned turtles. The Cryptodira are the larger of the two major clades of living testudinates. Living cryptodires are characterised by the ability to draw the head directly backwards within the shell, but this feature is not yet present in stem members of the clade. Kayentachelys aprix is one such stem cryptodire, known from the Early Jurassic of Arizona. The Meiolaniidae were often large tortoises with horn- or knob-like protrusions on the rear of the skull and an armoured tail surrounded by bony rings. Remains are known from South America and Australasia, and they survived in the latter region until the Holocene, only becoming extinct within the last 2000 years or so.

Among the major lineages of the crown group, the Cryptoderinea unite the Testudinoidea and Chelydridae on the basis of the arrangement of the articular surfaces of the cervical vertebrae (Joyce et al. 2004). The Chelydridae include the snapping turtles (Chelydra serpentina and Macroclemys temminckii) of North and South America, and the big-headed turtle (Platysternon megacephalum) of southeastern Asia. Members of this family have large heads with strong jaws, and limbs that cannot be fully retracted into the shell (Animal Diversity Web). The Sinemydidae from the Cretaceous and Palaeocene of Asia and North America may represent fossil relatives of the chelydrids. The Testudinoidea unite the pond turtles and terrestrial tortoises, with their total group (the Pantestudinoidea) including species with an ossified bridge connecting the plastron with the carapace (Joyce et al. 2004).

The Kinosternoidea are freshwater turtles found in North and South America, characterised by the loss of the extragular and pectoral scales of the plastron and the absence of scales on the skull roof. Within the Kinosternoidea, the Dermatemydidae are represented by a singly living species, the hickatee Dermatemys mawii of Central America. Agomphus, from the Late Cretaceous of North America, has historically been assigned to the Dermatemydidae but probably belongs to the kinosternoid stem group (Joyce et al. 2004).

The Chelonioidea include the living sea turtles, characterised by the modification of the legs into flippers with elongation of the third and fourth digits and flattening of the carpals and tarsals (Animal Diversity Web). They are first known from the Early Cretaceous of Brazil where the species Santanachelys gaffneyi represents a stem-group relative of the modern leatherback turtle (Joyce et al. 2004).

Characters (from Gaffney & Meylan 1988): Formed vertebral articulations; posterior section of canalis caroticus internus with relatively thick floor; plastral buttresses not reaching costal bones.

    |--Meiolaniidae [Meiolanoidea, Miolaniidae]GM88
    |    |--Niolamia argentina Ameghino 1899B93
    |    |--Ninjemys oweniWW10
    |    |--Warkalania carinaminorWW10
    |    `--Meiolania Owen 1886D07
    |         |--M. argentina Smith Woodward 1901F71
    |         |--M. brevicollisWW10
    |         |--M. damelipi White, Worthy et al. 2010WW10
    |         |--M. mackayi Anderson 1925F71
    |         |--M. oweni Woodward 1888B93
    |         `--M. platyceps Owen 1886WW10
    `--Cryptodira (see below for synonymy)JPG04
         |  i. s.: EmarginachelysGM88
         `--+--Cryptoderinea [Pancryptoderinea]JPG04
            |    |--PantestudinoideaJPG04
            |    |    |--LindholmemysJPG04
            |    |    |--MongolemysJPG04
            |    |    `--Testudinoidea [Emychelydia, Panemychelydia]GM88
            |    |         |--EmydidaeGM88
            |    |         `--PantestuguriaAS09
            |    `--PanchelydridaeJPG04
            |         |--SinemydidaeB93
            |         |    |--Sinemys lens Wiman 1930B93
            |         |    `--Protochelydra zangerli Erickson 1973GM88, B93
            |         `--Chelydridae [Chelydrinae, Chelydroidea]GM88
            |              |  i. s.: Devisia methodesB28
            |              |--Chelydra serpentina (Linnaeus 1758)GM88, JPG04 [=Testudo serpentinaJPG04]
            |              |    |--C. s. serpentinaN10
            |              |    |--C. s. acutirostrisN10
            |              |    |--C. s. osceolaN10
            |              |    `--C. s. rossignoniiN10
            |              `--PlatysterniniGM88
            |                   |--MacroclemysGM88 [=Macrochelys (l. c.)N10, Macroclemmys (l. c.)N10]
            |                   |    `--M. temminckii (Troost 1835) [=Chelonura temminckii]JPG04
            |                   `--Platysternina [Panplatysternon]GM88
            |                        |--ChelydropsisGM88
            |                        `--Platysternon [Platysternidae]AS09
            |                             `--P. megacephalum Gray 1831JPG04
               |    |--AgomphusJPG04
               |    `--Kinosternoidea [Kinosternoidae]JPG04
               |         |--Pankinosternidae [Kinosternia]JPG04
               |         |    |--HoplochelysGM88
               |         |    `--KinosternidaeGM88
               |         `--Dermatemydidae [Pandermatemys]GM88
               |              |--Baptemys Leidy 1873GM88, C77
               |              |    |--*B. wyomingensis Leidy 1870JPG04
               |              |    `--B. tricarinata Hay 1908B93
               |              `--DermatemysAS09
               |                   |--D. costilatus Cope 1875C77
               |                   |--D. mawii Gray 1847JPG04
               |                   `--D. wyomingensisC77
               `--Chelonioidea [Euchelonioidea, Panchelonioidea]JPG04
                    |  i. s.: CorsochelysGM88
                    |         RhinochelysGM88
                    |    |  i. s.: Santanachelys gaffneyiJPG04
                    |    |--Allopleuron Baur 1888GM88, F91
                    |    |--DermochelyoidaeGM88
                    |    `--DesmatochelyidaeB93
                    |         |--Desmatochelys lowi Williston 1898GM88, B93
                    |         `--Notochelone costata (Owen 1882)B93
                         |  i. s.: EuclastesJPG04
                         |--Toxochelys [Toxochelyinae]GM88
                         |    `--T. latiremis Cope 1873B93
                         `--+--Ctenochelys [Lophochelyinae]GM88
                            |    |--C. acris Zangerl 1953B93
                            |    `--C. tenuitesta Zangerl 1953B93
                            `--+--Osteopyginae [Osteopygidae]TH02
                               |    |--Osteopygis emarginatus Cope 1868B93
                               |    |--RhetechelysGM88
                               |    `--ErquelinnesiaTH02
                               |         |--E. gosseleti (Dollo 1886)B93
                               |         `--E. planimentaTH02
                                       |--Argillochelys Lydekker 1889TH02
                                       |--Puppigerus Cope 1871TH02
                                       |    `--P. camperiTH02
                                       `--Eochelone Dollo 1903GM88, TH02
                                            `--E. brabanticaTH02

Cryptodira [Chelomacryptodira, Chersemyda, Panchersemyda, Pantrionychoidea, Polycryptodira, Procoelocryptodira, Trionychoidea]JPG04

*Type species of generic name indicated


[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.

[B93] Benton, M. J. 1993. Reptilia. In: Benton, M. J. (ed.) The Fossil Record 2 pp. 681–715. Chapman & Hall: London.

[B28] Betrem, J. G. 1928. Monographie der Indo-Australischen Scoliiden mit zoogeographischen Betrachtungen. H. Veenman & Zonen: Wageningen.

[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.

[F71] Fletcher, H. O. 1971. Catalogue of type specimens of fossils in the Australian Museum, Sydney. Australian Museum Memoir 13: 1–167.

[F91] Freess, W. B. 1991. Beiträge zur Kenntnis von Fauna und Flora des marinen Mitteloligozäns bei Leipzig. Altenburger Naturwissenschaftliche Forschungen 6: 3–74.

[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.

[JPG04] Joyce, W. G., J. F. Parham & J. A. Gauthier. 2004. Developing a protocol for the conversion of rank-based taxon names to phylogenetically defined clade names, as exemplified by turtles. Journal of Paleontology 78 (5): 989–1013.

[N10] Naish, D. 2010. Tetrapod Zoology: Book One. CFZ Press: Bideford (UK).

[TH02] Tong, H., & R. Hirayama. 2002. A new species of Tasbacka (Testudines: Cryptodira: Cheloniidae) from the Paleocene of the Ouled Abdoun phosphate basin, Morocco. Neues Jahrbuch für Geologie und Paläontologie Monatshefte 2002 (5): 277–294.

Leave a comment

Your email address will not be published. Required fields are marked *