Carettochelys insculpta is widely considered one of the most interesting and unique of the living turtles. A thick protruding snout with laterally-placed nares gives the head of C. insculpta a superficially pig-like appearance. The paddle-like forefeet are used to propel C. insculpta (much like sea turtles and unlike most other aquatic turtles, which use their hindlimbs for propulsion) through the freshwater streams, rivers, lakes, and lagoons of Papua New Guinea and the Daly, Victoria, and Alligator river drainages of the Northern Territory, Australia (Ernst and Barbour, 1989). The pig-nosed turtle, perhaps not surprisingly given its name, is known to consume a wide variety of food items ranging from fruits, seeds, roots, and leaves to snails, insects, and small fish.

Carettochelys insculpta is the sole living member of the Carettochelyidae, a group whose stratigraphic range extends as far back as the Mesozoic (Cretaceous of central Asia). Tertiary records of carettochelyids are relatively abundant and allocated to one of two primary groups, the Anosterinae and Carettochelyinae. Fossils from both groups are common in the Eocene of Asia, Europe, and North America, but only the Carettochelyinae (which includes the living C. insculpta) appears to have survived into the Miocene. Miocene-aged carettochelyine fossils are recovered from Africa, Arabia, Europe, and New Guinea.

Cladistic analyses of both morphological and molecular characters place the Carettochelyidae as a close relative to the soft-shelled turtles of the Trionychidae (Meylan, 1987; Meylan and Gaffney, 1989; Shaffer et al., 1997). Skeletal characters that diagnose carettochelyids and trionychids as a monophyletic group include fusion of the left and right premaxillae, lack of bony suturing between the carapace and plastron, strong suturing of the ribs to the vertebral centra, a relatively long coracoid process, contact between the radius and ulna adjacent to the manus, and three or fewer clawed digits.

Other skeletal characters of systematic interest that are present in C. insculpta include reduction of the vomer, anterior truncation of the palatines, lack of an external process of the pterygoid, posterior closure of the incisura columella auris, relative lack of cheek emargination, division of the pterygoids by the basisphenoid, ten or fewer peripherals, and the presence of processes extending ventrally from the nuchal.

This specimen was collected from the Indonesian portion of New Guinea. It was made available to The University of Texas High-Resolution X-ray CT Facility for scanning courtesy of the Florida Museum of Natural History. 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.

This specimen was scanned by Matthew Colbert on 6 November 2003 along the horizontal axis for a total of 204 1024x1024 pixel slices. Each slice is 0.5 mm thick, with an interslice spacing of 0.4 mm and a field of reconstruction of 268 mm.

Literature

Baur, G. 1891. On the relations of Carettochelys, Ramsay. American Naturalist 25:631-639.

Beggs, K., J. Young, A. Georges, and P. West. 2000. Ageing the eggs and embryos of the pig-nosed turtle, Carettochelys insculpta (Chelonia: Carettochelydidae), from northern Australia. Canadian Journal of Zoology 78:373-392.

Bickham, J. W., and J. L. Carr. 1983. Taxonomy and phylogeny of the higher categories of cryptodiran turtles based on a cladistic analysis of chromosomal data. Copeia 1983:918-932.

Bickham, J. W., J. J. Bull, and J. M. Legler. 1983. Karyotypes and evolutionary relationships of trionychid turtles. Cytologia 48:177-184.

Doody, J. S., A. Georges, J. E. Young, M. D. Pauza, A. L. Pepper, R. L. Alderman, and M. A. Welsh. 2001. Embryonic aestivation and emergence behaviour in the pig-nosed turtle, Carettochelys insculpta. Canadian Journal of Zoology 79:1062-1072.

Ernst, C. H., and R. W. Barbour. 1989. Turtles of the World. Smithsonian Institution Press, Washington D. C. 311 pp.

Friar, W. 1985. The enigmatic plateless river turtle, Carettochelys, in serological survey. Journal of Herpetology 19:515-523.

Gaffney, E. S. 1979. Comparative cranial morphology of Recent and fossil turtles. Bulletin of the American Museum of Natural History. 164:67-376.

Gaffney, E. S. 1981. A review of the fossil turtles of Australia. American Museum Novitates. 2720:1-38.

Glaessner, M. F. 1942. The occurrence of the New Guinea turtle (Carettochelys) in the Miocene of Papua. Records of the Australian Museum 1847:711-716.

Georges, A., and R. Kennett. 1989. Dry season distribution and ecology of Carettochelys insculpta (Chelonia: Carettochelyidae) in Kakadu National Park, northern Australia. Australian Wildlife Research 16:323-336.

Joyce, W. G., N. Klein, and T. Mörs. 2004. Carettochelyine turtle from the Neogene of Europe. Copeia 2004:406-411.

Meylan, P. A. 1987. The phylogenetic relationships of soft-shelled turtles (Family Trionychidae). Bulletin of the American Museum of Natural History 186:1-101.

Meylan, P. A. 1988. Peltochelys Dollo and the relationships among the genera of the Carettochelyidae (Testudines: Reptilia). Herpetologica 44:440-450.

Meylan, P. A., and E. S. Gaffney. 1989. The skeletal morphology of the Cretaceous turtle, Adocus, and the relationships among the Trionychoidea. American Museum Novitates 2941:1-60.

Ramsey, E. P. 1887. On a new genus and species of fresh water tortoise from the Fly River, New Guinea. Proceedings of the Linnean Society of New South Wales 1:158-162.

Shaffer, H. B., P. Meylan, and M. L. McKnight. 1997. Tests of turtle phylogeny: molecular, morphological, and paleontological approaches. Systematic Biology 46:235-268.

Waite, E. R. 1905. The osteology of the New Guinea turtle (Carettochelys insculpta, Ramsay). Records of the Australia Museum 6:110-118.

Walther, W. G. 1922. Die Neu-Guinea Schildkröte Carettochelys insculpta Ramsay. Nova Guinea 13:607-702.

Webb, G. J. W., D. Choquenot, and P. J. Whitehead. 1986. Nests, eggs, and embryonic development of Carettochelys insculpta (Chelonia: Carettochelyidae) from northern Australia. Journal of Zoology (B) 1986:521-550.

Winokur, R. M. 1982. Erectile tissue and smooth muscle in snouts of Carettochelys insculpta, trionychids, and other Chelonia. Zoomorphology 101:83-94.

Zangerl, R. 1959. Rudimentäre Carapaxbeschuppung bei jungen Exemplaren von Carettochelys und ihre morphogenetische Bedeutung. Naturforschenden Gesellshaft, Zürich: 138-147.

Zangerl, R. 1969. The turtle shell, p. 311-339. In: Biology of the Reptilia, Morphology A, Volume 1. C. Gans, A. d. A. Bellairs, and T. S. Parsons (eds.). Academic Press, London.

Links

Carettochelys insculpta on the Integrated Taxonomic Information System.

Carettochelys insculpta on Tortoise.org

Images and information about Carettochelys at Carettochelys.com.

The research website of Dr. Eugene Gaffney of the American Museum of Natural History

Roll spin as the shell and skin fade (2mb)	Roll spin with shell removed (1.5mb)

Front page image.