Project 871: Eugene S. Gaffney, Thomas H. V. Rich, Pat Vickers Rich, Andrew Eric Constantine, Raul Vacca, Lesley Kool. 2007. Chubutemys, a new eucryptodiran turtle from the early Cretaceous of Argentina, and the relationships of the Meiolaniidae. American Museum Novitates. 3599.
Specimen: † Chubutemys (MPEF:PV1236)
View: Dorsal view of skull

Abstract

Chubutemys copelloi is the oldest nonmarine cryptodire from South America represented by a skull. The skull and associated postcranial fragments are from the Aptian Cerro CostaŠno Member of the Cerro Barcino Formation of Chubut, Argentina. Chubutemys has a processus trochlearis oticum, showing that it is a cryptodire, and an enclosed canalis caroticus internus extending to the posterior margin of the pterygoid, showing that it is a eucryptodire. The skull of Chubutemys is similar to that of other primitive eucryptodires, particularly Dracochelys, but also to Hangaiemys, Judithemys, Sinemys, and Ordosemys. Chubutemys differs from all these, however, in possessing a solidly roofed skull, formed by long, wide parietals, rather than a posterior emargination. Chubutemys also differs from these taxa in having no cheek emargination. A phylogenetic analysis using PAUP* analyzed 104 parsimony-informative characters resolving into one most parsimonious cladogram of 224 steps, a consistency index of 0.55, and a retention index of 0.74. The phylogenetic analysis weakly joins Chubutemys and meiolaniids on the basis of the prefrontal-postorbital contact. Chubutemys also has a fully roofed skull and slitlike posterior opening of the foramen caroticum laterale (foramen posterius canalis caroticus laterale), features to be expected in a meiolaniid sister taxon. Chubutemys provides further evidence that meiolaniids are related to 'basal' eucryptodires ('sinemydids/macrobaenids'), that is, eucryptodires outside the living Cryptodira, the Polycryptodira. The basicranial morphology of meiolaniids, with an intrapterygoid slit, rather than being a unique feature of the group is instead a modified state of the primitive eucryptodire condition, as seen in such forms as Chubutemys, Dracochelys, Ordosemys, and Sinemys. The intrapterygoid slit of meiolaniids is homologous with the pterygoid flange associated with the foramen caroticum laterale (foramen posterius canalis caroticus laterale of Sukhanov) in non-Polycryptodiran eucryptodires like Ordosemys. Chubutemys shows that nonmarine eucryptodires were present in South America in the Cretaceous, as they were in North America, central Asia, and Australia


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Project DOI: 10.7934/P871, http://dx.doi.org/10.7934/P871
This project containsMatrices
  • 1 Media
  • 1 Matrix
  • 28 Taxa
  • 2 Specimens
  • 111 Characters


Download Project SDD File
Total scored cells: 2512
Total media associated with cells: 0
Total labels associated with cell media: 0
Characters
Total characters: 111
Total characters with associated media: 0
Total characters with media with labels: 0
Total character states: 242
Total character states with associated media: 0
Total character states with media with labels:0
Total unordered/ordered characters:111/0
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MorphoBank Project 871


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    MorphoBank Curator
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    Last logged in 04/01/13
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    Maureen Admin
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    Eugene Gaffney
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    Taxonomic Overview for Matrix 'M1949' (28 Taxa)

    taxon unscored
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    [1] Synapsida/Diapsida
    Last Modified in 12/05/13
    27848400003
    [2] † Proganochelys
    Last Modified in 12/05/13
    210910900003
    [3] † Australochelys
    Last Modified in 12/05/13
    66454500003
    [4] † Palaeochersis
    Last Modified in 12/05/13
    36757500003
    [5] † Proterochersis
    Last Modified in 12/05/13
    88232300003
    [6] Megapleurodira
    Last Modified in 12/05/13
    112711000003
    [7] † Kayentachelys
    Last Modified in 12/05/13
    510610600003
    [8] † Kallokibotion
    Last Modified in 12/05/13
    1110010000003
    [9] † Mongolochelys
    Last Modified in 12/05/13
    910210200003
    [10] † Pleurosternidae
    Last Modified in 12/05/13
    311110800003
    [11] † Baenidae
    Last Modified in 12/05/13
    111311000003
    [12] † Xinjiangchelys
    Last Modified in 12/05/13
    41727000003
    [13] † Solnhofia
    Last Modified in 12/05/13
    20919100003
    [14] † Plesiochelyidae
    Last Modified in 12/05/13
    311010800003
    [15] † Meiolania
    Last Modified in 12/05/13
    510710600003
    [16] † Ninjemys
    Last Modified in 12/05/13
    67444400003
    [17] † Niolamia
    Last Modified in 12/05/13
    58535300003
    [18] † Chubutemys
    Last Modified in 12/05/13
    55565600003
    [19] † Sinemys
    Last Modified in 12/05/13
    14979700003
    [20] † Otwayemys
    Last Modified in 12/05/13
    76353500003
    [21] † Hangaiemys
    Last Modified in 12/05/13
    21909000003
    [22] † Dracochelys
    Last Modified in 12/05/13
    33787800003
    [23] † Ordosemys
    Last Modified in 12/05/13
    16959500003
    [24] † Judithemys
    Last Modified in 12/05/13
    910210200003
    [25] Chelydridae
    Last Modified in 12/05/13
    011711100003
    [26] Chelonioidea
    Last Modified in 12/05/13
    012811100003
    [27] Trionychoidea
    Last Modified in 12/05/13
    012211100003
    [28] Testudinoidea
    Last Modified in 12/05/13
    012011100003


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    Bibliography823




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