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Chelus fimbriatus, the mata mata, is a member of Pleurodira (side-necked turtles). Within Pleurodira it is a member of Chelidae, a clade found today only in South America and Australia (see Gaffney website for more information on pleurodires and cryptodires). Gaffney (1977) and Seddon et al. (1997) conducted systematic analyses of recent chelids; Sánchez-Villagra et al. (1995) studied Chelus fimbriatus; and Wood (1976) described Chelus fossils.

The skeleton of Chelus fimbriatus has not been described or figured in its entirety. Gaffney (1979) produced the only labeled figures of the skull (figs. 23, 70, 88, 144, and 150); other figures of the skull may be found in Boulenger (1889: fig. 52; includes jaw) and Pritchard and Trebbau (1984: fig 16). Boulenger (1889: fig. 53) and Pritchard and Trebbau (1984: fig. 16) also figured the unlabeled shell of Chelus; current shell terminology can be found in Zangerl (1969). Rütimeyer (1873: plate 8, fig. 5) provided an excellent internal view of the carapace; Hoffstetter and Gasc (1969: fig. 13) figured all of the cervical vertebrae; and Kasper (1903: plate 1) figured the atlas-axis complex of Chelus and other chelids.

This specimen was made available to the University of Texas High-Resolution X-ray CT Facility for scanning by Dr. Adam Summers of the Department of Ecology and Evolutionary Biology, University of California, Irvine. Funding for scanning was provided by a National Science Foundation Digital Libraries Initiative grant to Dr. Timothy Rowe of The University of Texas at Austin.

The whole specimen was scanned by Matthew Colbert on 28 October 2001 along the coronal axis for a total of 400 512x512 pixel slices. Each slice is 1.0 mm thick, with an interslice spacing of 0.9 mm (for a slice overlap of 0.1 mm) and a field of reconstruction of 255 mm.

To the left is an example of a reduced slice through the braincase of Chelus. Click on the thumbnail for an unreduced version.

Literature

Boulenger, G. A. 1889. Catalogue of the chelonians, rhynchocephalians and crocodiles in the British Museum (Natural History), London, printed by order of the Trustees of the British Museum (Natural History). Taylor and Francis, London. 311 pp.

Fuchs, H. 1931. Über den Unterkiefer und die Unterkiefernerven (Ramus tertius nervi trigemini et Chorda tympani) der Arrauschildkröte (Podocnemis expansa). Nebst Bermerkungen zur Kiefergelenksfrage. Zeitschr. Anat. Entwicklungsgeschichte 94:206-274.

Gaffney, E. S. 1972. An illustrated glossary of turtle skull nomenclature. American Museum Novitates 2486:1-33.

Gaffney, E. S. 1977. The side-necked turtle family Chelidae: A theory of relationships using shared derived characters. American Museum Novitates 2620:1-28.

Gaffney, E. S. 1979. Comparative cranial morphology of recent and fossil turtles. Bulletin of the American Museum of Natural History 164:65-375.

Gaffney, E. S. 1990. Comparative osteology of the Triassic turtle Proganochelys. Bulletin of the American Museum of Natural History 194:1-263.

Gaffney, E. S., and P. A. Meylan. 1988. A phylogeny of turtles; pp. 157-219 in M. J. Benton (ed.), The Phylogeny and Classification of the Tetrapods, Volume 1: Amphibians, Reptiles, Birds. Systemtics Association Special Volume 35A, Clarendon Press, Oxford.

Hoffstetter, R., and J.-P. Gasc. 1969. Vertebrae and ribs of modern reptiles; pp. 201-310 in C. Gans, A. d'A Bellairs, and T. Parsons (eds.), Biology of the Reptilia Volume 1. Academic Press, New York.

Kasper, A. 1903. Ueber den Atlas und Epistropheus bei den pleurodiren Schildkröten. Arbeiten Zool. Inst., Univ. Wien 14:137-172.

Pritchard, P. C. H., and P. Trebbau. 1984. The Turtles of Venezuela. Society for the Study of Amphibians and Reptiles. Oxford, Ohio. 414 pp.

Rütimeyer, L. 1873, Die fossilen Schildkröten und der übrigen Jura-formation. enkschr. DSchweizer. Naturf. Gessell. 25:1-185.

Sánchez-Villagra, M. R., P. C. H. Pritchard, A. Paolillo, and O. J. Linares. 1995. Geographic variation in the matamata turtle, Chelus fimbriatus, with observations on its shell morphology and morphometry. Chelonian Conservation and Biology 1:293-300.

Seddon, J. M., A. Georges, P. R. Baverstock, and W. McCord. 1997. Phylogenetic relationships of chelid turtles (Pleurodira: Chelidae) based on mitochondrial 12S rRNA gene sequence variation. Molecular Phylogenetics and Evolution 7:55-61.

Wood, R. C. 1976. Two new species of Chelus (Testudines: Pleurodira) from the late Tertiary of northern South America. Breviora 435:1-26.

Zangerl, G. R. 1969. The turtle shell, pp.311-339 in C. Gans, A. d'A Bellairs, and T. Parsons (eds.), Biology of the Reptilia Volume 1. Academic Press, New York.

Links

William Espenshade's Mata Mata article from the Tortuga Gazette

Dr. David Kirkpatrick's Mata Mata article from Reptile & Amphibian Magazine

A Mata Mata fact sheet from CentralPets.com

Gene Gaffney's Phylogeny of Turtles (AMNH) (requires Flash plug-in)

Chelus fimbriatus on CalPhotos.

Roll spin with shell removed (2mb)	Pitch spin with shell removed (1.9mb)

Yaw spin with shell removed (1.2mb)